На главную              К списку выставок

Месторождения стратегических металлов: закономерности размещения, источники вещества, условия и механизмы образования

Журнальные статьи

1.
Achzet B., Helbig C. How to evaluate raw material supply risks—an overview // Resources Policy. 2013. Vol. 38, № 4. P. 435–447.

Some strategic raw materials do have an extremely unsecure supply situation. Several working groups around the world have made criticality assessments for metallic raw materials to analyze the driving impact factors for this instability. However, the influences on raw material availability are manifold and therefore criticality assessment methods are very heterogeneous. Here we give an overview about the differences and similarities of supply risk evaluation in 15 criticality assessment methods. We take the example of Indium, which has been rated in 60% of these criticality studies, and show which data base is used for supply risk evaluation. Our results show a lack of consensus about which indicators give reliable information for raw material supply risk and how these indicators should be aggregated. We anticipate our essay to be a starting point for more justified indicator selection and weighting in criticality assessments.

2.
Acosta-Gongora P. et al. Genesis of the Paleoproterozoic NICO iron oxide–cobalt–gold–bismuth deposit, Northwest Territories, Canada: Evidence from isotope geochemistry and fluid inclusions // Precambrian Research. 2015. Vol. 268. P. 168–193.

The NICO deposit is located in the southern portion of the Paleoproterozoic Great Bear magmatic zone, Northwest Territories, Canada. The majority of the mineralization lies within the Bowl Zone, hosted by the Treasure Lake Group (TLG)?, where heavily altered precursor rocks are interpreted to be carbonate-?rich wackes and siltstones. These rocks are crosscut by a set of pre-?ore quartz ± calcite + amphibole + K-?feldspar veins (S1)?. The Co-?Au-?Bi (±W-?Cu-?Mo) mineralization at NICO is contained in stratabound ore lenses within the Bowl Zone, and comprises a prograde assemblage of Co-?rich arsenopyrite (arsenopyrite I) and loellingite, cobaltite, pyrite, actinolite, ferrohornblende, biotite and rare scheelite (±molybdenite) along with minor magnetite and amphibole. Retrograde assemblages resulted from re-?crystn. of the Co-?bearing phases to form arsenopyrite II and III, along with pptn. of marcasite, pyrite, hastingsite, native Bi-?Au (±Te) and minor bismuthinite and magnetite. The latest stage of retrograde mineralization comprises chalcopyrite, hastingsite, chlorite, and hematite (±emplectite)?. Two sets of barren quartz ± dolomite + amphibole + K-?feldspar + chalcopyrite veins (S2 and S3) post-?date the mineralization. The Southern Breccia zone hosts minor U-?Cu-?Mo mineralization and is interpreted to be the deepest portion of the NICO system. Two molybdenite samples from the Bowl Zone and the Southern Breccia yielded Re-?Os ages of 1865 ± 9 and 1877 ± 8 Ma, resp., consistent with the interpreted ca. 1870 Ma age of the NICO deposit. This age is also synchronous with the onset of magmatism in the Great Bear magmatic arc (ca. 1875-?1850 Ma)?.Ore mineral ?34S values (3.3-?6.7‰, sulfides) indicate that crustal sulfur was assimilated by upwelling felsic magmatic melts. The ?18O values of the fluids pptg. magnetite and Co-?rich arsenopyrite (6 and 8‰)?, and from pre- and syn-?mineralization magnetite (-?0.8 to 1.5‰) support a magmatic-?hydrothermal origin of the fluids. Two out of three calcite samples from pre-?(S1) and post-?ore (S3) veins have also ?13C values consistent with a magmatic origin (-?5.5 to -?3.6‰)?. However, one calcite sample from the S3 veins has a value that indicates a reduced sulfur source (-?15.6‰)?. This value is similar to those of the much younger (<1843 Ma) giant quartz veins cutting the GBMZ rocks. The quartz ?18O values suggest that S1 (12.7‰) formed at higher temps. than S2 (13.2-?19.14‰) and S3 (9.4-?17.1‰)?, or that in the latter two generations of veins, 18O was enriched during fluid?/rock equilibration.Secondary trails of native Bi in S1 vein quartz are assocd. with liq.-?vapor (LV) and liq.-?vapor-?halite (LVS) inclusions, which indicates that Bi, and possibly Au, were transported in saline to hyper-?saline brines (LV-?Bi, 2-?16 wt.?% NaCl equiv., 8-?22 wt.?% CaCl2 equiv.; LVS-?Bi, >37 wt.?% NaCl equiv.)?, with homogenization temps. of 137-?216 °C and 192 to >350 °C for LV-?Bi (ThL+V>L) and LVS-?Bi (ThL+S>L)?, resp. The presence of calcium-?rich fluids might indicate extensive equilibration of those solns. with the host TLG rocks. If a pressure correction is applied to the LV inclusions using a min. entrapment temp. of 271.4 °C (the Bi m.p.)?, a min. crystn. depth of between approx. 5 and 8 km is indicated.Trace element analyses carried out in this study and compiled from Acosta-?G?ongora et al. (2014) show that the least altered metasedimentary TLG rocks contain up to six times more As (Carbonate unit, 30.5 ppm) than the av. upper continental crust. Conversely, concns. of Au (<2 ppb)?, Co (10 ppm) and Cu (12 ppm) are lower than the crustal values. As such, it is possible that the TLG was a source of As, but is a less likely source of Au, Co and Cu for the NICO deposit; this further supports a magmatic-?hydrothermal origin for the metals. Nonetheless, the plurikilometer alteration halo of the NICO system indicates that large amts. of elements could have been leached from th

3.
Afify A.M., Sanz-Montero M.E., Calvo J.P. Ironstone deposits hosted in Eocene carbonates from Bahariya (Egypt)—New perspective on cherty ironstone occurrences // Sedimentary Geology. 2015. Vol. 329. P. 81–97.

This paper gives new insight into the genesis of cherty ironstone deposits. The research was centered on well-?exposed, unique cherty ironstone mineralization assocd. with Eocene carbonates from the northern part of the Bahariya Depression (Egypt)?. The economically important ironstones occur in the Naqb Formation (Early Eocene)?, which is mainly formed of shallow marine carbonate deposits. Periods of lowstand sea-?level caused extensive early dissoln. (karstification) of the depositional carbonates and dolomitization assocd. with mixing zones of fresh and marine pore-?water. In faulted areas, the Eocene carbonate deposits were transformed into cherty ironstone with preservation of the precursor carbonate sedimentary features, i.e. skeletal and non-?skeletal grain types, thickness, bedding, lateral and vertical sequential arrangement, and karst profiles. The ore deposits are composed of iron oxyhydroxides, mainly hematite and goethite, chert in the form of micro- to macro-?quartz and chalcedony, various manganese minerals, barite, and a no. of subordinate sulfate and clay minerals. Detailed petrog. anal. shows that quartz and iron oxides were coetaneous and selectively replaced carbonates, the coarse dolomite crystals having been preferentially transformed into quartz whereas the micro-?cryst. carbonates were replaced by the iron oxyhydroxides.A no. of petrog., sedimentol. and structural features including the presence of hydrothermal-?mediated minerals (e.g., jacobsite)?, the geochem. of the ore minerals as well as the structure-?controlled location of the mineralization suggest a hydrothermal source for the ore-?bearing fluids circulating through major faults and reflect their proximity to centers of magmatism. The proposed formation model can contribute to better understanding of the genetic mechanisms of formation of banded iron formations (BIFs) that were abundant during the Precambrian.

4.
Aliyari F. et al. Geochemistry of hydrothermal alteration at the Qolqoleh gold deposit, northern Sanandaj–Sirjan metamorphic belt, northwestern Iran: Vectors to high-grade ore bodies // Journal of Geochemical Exploration. 2014. Vol. 140. P. 111–125.

The Qolqoleh orogenic gold deposit in the northern part of the Sanandaj-?Sirjan metamorphic belt in northwestern Iran is hosted by a steeply dipping sequence of greenschist facies Cretaceous volcano-?sedimentary rocks, including mafic to intermediate metavolcanic rocks, sericite and chlorite schist, and marble. Geochem. and petrochem. data including the ? REE, (La?/Yb)?N and Eu?/Eu* ratios were obtained from country rocks, ore-?enveloping alteration zones, and mineralized zones to assess the nature of the trace element and rare earth element (REE) interaction between the wall rock and the mineralizing fluid.Quartz-?sulfide veins at the deposit are characterized by a pyrite-?pyrrhotite-?chalcopyrite-?sphalerite-?arsenopyrite-?native gold assemblage. Alteration halos border the mineralized zones and broadly comprise: (1) an outer carbonate-?chlorite alteration zone in all rock types, particularly in chlorite schist; (2) a middle sericite-?carbonate alteration zone in the sericite schist; and (3) an inner quartz-?sulfide alteration zone in sericite schist and mafic to intermediate metavolcanic rocks.The geochem. data indicate that the concns. of Al2O3, P2O5, TiO2, Y, and Zr are relatively const., suggesting that these elements were the least mobile during hydrothermal activity. Using Al2O3 as the immobile component, there is evidence for mobility of trace elements, particularly light REE, TiO2, and Zr in the altered wall rocks. The altered rocks show a relatively light REE depletion ((La?/Yb)?N ? 9.41)?, which clearly correlates with the grades of gold mineralization and intensity of the alteration (3 ppm Au)?. The depletion of light REE is best indicated by a decrease in (La?/Yb)?N as shown by ratios of 10.5 to 11.8. Wall rock decarbonation reactions during infiltration of the mineralizing fluid resulted in differential mobilization of REE, from a fluid with initially low REE content.The overall trace element geochem. of the altered wall rock is controlled by the initial compn. of the wall rocks and the ore-?fluid compn. Hydrothermal ore-?forming fluids are recognized as CO2-?rich near-?neutral reduced fluids with high values of H2S, K, and S content. Obsd. variability in alteration halos at the Qolqoleh deposit points to major differences in REE and trace element content in original host rocks that have interacted with a relatively similar ore fluid. Therefore, depending on the compn. of each host rock lithol., the geochem. of hydrothermal alteration (e.g., ? REE content and (La?/Yb)?N ratios) and alteration mineralogy including the carbonate-?sericite-?quartz-?sulfide assemblages may be used as a primary tool for lithogeochem. exploration for gold deposits in northwestern Iran.

5.
Baioumy H.M. Rare earth elements, S and Sr isotopes and origin of barite from Bahariya Oasis, Egypt: Implication for the origin of host iron ores // Journal of African Earth Sciences. 2015. Vol. 106. P. 99–107.

Based on their occurrences and relation to the host iron ores, barites are classified into: (1) fragmented barite occurs as pebble to sand-?size white to yellowish white barite along the unconformity between the Bahariya Formation and iron ores, (2) interstitial barite is present as pockets and lenses of large and pure crystals inside the iron ores interstitial barite inside the iron ores, and (3) disseminated barite occurs at the top of the iron ores of relatively large crystals of barite embedded in hematite and goethite matrix. In the current study, these barites have been analyzed for their rare earth elements (REE) as well as strontium and sulfur isotopes to assess their source and origin as well as the origin of host iron ores. Barite samples from the three types are characterized by low ?REE contents ranging between 12 and 21 ppm. Disseminated barite shows relatively lower ?REE contents (12 ppm) compared to the fragmented (19 ppm) and interstitial (21 ppm) barites. This is probably due to the relatively higher Fe2O3 in the disseminated barite that might dil. its ?REE content. Chondrite-?normalized REE patterns for the three barite mineralizations exhibit enrichment of light rare earth elements (LREE) relative to heavy rare earth elements (HREE) as shown by the high (La?/Yb)?N ratios that range between 14 and 45 as well as pronounced neg. Ce anomalies varying between 0.03 and 0.18. The 87Sr?/86Sr ratios in the analyzed samples vary between 0.707422 and 0.712237. These 87Sr?/86Sr values are higher than the 87Sr?/86Sr ratios of the seawater at the time of barite formation (Middle Eocene with 87Sr?/86Sr ratios of 0.70773 to 0.70778) suggesting a contribution of hydrothermal fluid of high Sr isotope ratios. The ?34S values in the analyzed barites range between 14.39‰ and 18.92‰. The lower ?34S ratios in the studied barites compared with those of the seawater at the time of barite formation (Middle Eocene with ?34S ratios of 20-?22‰) is attributed to a possible contribution of hydrothermal fluid of low ?34S values that lowered the ?34S values in the studied barites. Rare earth elements distribution and patterns, as well as strontium and sulfur isotopes suggest a mixing of seawater and a hydrothermal fluid as possible sources for barite mineralizations in the Bahariya Oasis. The seawater source is suggested from the low Ce?/La ratios, "V" shape of the rare earth patterns and pronounced neg. Ce anomalies. On the other hand, the hydrothermal fluid contribution is evident from the low concns. of rare earth and the deviation in both S and Sr isotopic compns. from those of the seawater during the time of barites formation (Middle Eocene)?. The relatively heterogeneous Sr and S isotope ratios among the studied barites suggest the Bahariya Formation and Basement Complex as possible sources of the hydrothermal fluids. The similarity in the REE as well as S and Sr isotopic compns. of the three types of barite suggest that they form simultaneously. As the geol. and occurrence of the barites suggest a genetic relationship between these barites and the host iron ores, the mixed seawater and hydrothermal sources model of the barites is still applicable for the source of the host iron ores.

6.U28275
Barrie C.D. et al. Pyrite deformation textures in the massive sulfide ore deposits of the Norwegian Caledonides // Tectonophysics. 2010. Vol. 483, № 3-4. P. 269–286.

The Norwegian Caledonides represent a belt of late Precambrian to early Palaeozoic rocks, emplaced as a series of nappes onto the Fennoscandian basement. Massive sulfide orebodies occur along virtually the whole length of the orogenic belt making it possible to study deposits of a similar origin, chem. and mineralogy but variably deformed at different metamorphic conditions. Samples from seven pyrite-?rich ore deposits deformed at temps. from ? 320 °C to ? 610 °C have been investigated using reflected light petrog. observation, orientation contrast (OC) imaging and electron backscatter diffraction (EBSD)?. While a range of brittle, annealment and growth textures are preserved in the deposits, all preserve evidence for lattice misorientation and low-?angle (? 2°) sub-?grain boundary development indicative of dislocation creep. These results are at odds with those implied from the published pyrite deformation mechanism map, which suggest that pyrite does not deform by plastic mechanisms at natural geol. strain-?rates and that the brittle-?ductile transition is at ? 425 °C. Our results imply that pyrite is more ductile than generally inferred and the current deformation mechanism map needs to be revised with plastic deformation mechanisms operating at a much wider range of temp. and strain-?rate conditions.

7.U1045X
Bekker A. et al. Iron Formation: The Sedimentary Product of a Complex Interplay among Mantle, Tectonic, Oceanic, and Biospheric Processes // Economic Geology. 2010. Vol. 105, № 3. P. 467–508

A review. Iron formations are economically important sedimentary rocks that are most common in Precambrian sedimentary successions. Although many aspects of their origin remain unresolved, it is widely accepted that secular changes in the style of their deposition are linked to environmental and geochem. evolution of Earth. Two types of Precambrian iron formations have been recognized with respect to their depositional setting. Algoma-?type iron formations are interlayered with or stratigraphically linked to submarine-?emplaced volcanic rocks in greenstone belts and, in some cases, with volcanogenic massive sulfide (VMS) deposits. In contrast, larger Superior-?type iron formations are developed in passive-?margin sedimentary rock successions and generally lack direct relationships with volcanic rocks. The early distinction made between these two iron-?formation types, although mimimized by later studies, remains a valid first approxn. Texturally, iron formations were also divided into two groups. Banded iron formation (BIF) is dominant in Archean to earliest Paleoproterozoic successions, whereas granular iron formation (GIF) is much more common in Paleoproterozoic successions. Secular changes in the style of iron-?formation deposition, identified more than 20 years ago, have been linked to diverse environmental changes. Geochronol. studies emphasize the episodic nature of the deposition of giant iron formations, as they are coeval with, and genetically linked to, time periods when large igneous provinces (LIPs) were emplaced. Superior-?type iron formation first appeared at ca. 2.6 Ga, when construction of large continents changed the heat flux at the core-?mantle boundary. From ca. 2.6 to ca. 2.4 Ga, global mafic magmatism culminated in the deposition of giant Superior-?type BIF in South Africa, Australia, Brazil, Russia, and Ukraine. The younger BIFs in this age range were deposited during the early stage of a shift from reducing to oxidizing conditions in the ocean-?atm. system. Counterintuitively, enhanced magmatism at 2.50 to 2.45 Ga may have triggered atm. oxidn. After the rise of atm. oxygen during the GOE at ca. 2.4 Ga, GIF became abundant in the rock record, compared to the predominance of BIF prior to the Great Oxidn. Event (GOE)?. Iron formations generally disappeared at ca. 1.85 Ga, reappearing at the end of the Neoproterozoic, again tied to periods of intense magmatic activity and also, in this case, to global glaciations, the so-?called Snowball Earth events. By the Phanerozoic, marine iron deposition was restricted to local areas of closed to semiclosed basins, where volcanic and hydrothermal activity was extensive (e.g., back-?arc basins)?, with ironstones addnl. being linked to periods of intense magmatic activity and ocean anoxia. Late Paleoproterozoic iron formations and Paleozoic ironstones were deposited at the redoxcline where biol. and nonbiol. oxidn. occurred. In contrast, older iron formations were deposited in anoxic oceans, where ferrous iron oxidn. by anoxygenic photosynthetic bacteria was likely an important process. Endogenic and exogenic factors contributed to produce the conditions necessary for deposition of iron formation. Mantle plume events that led to the formation of LIPs also enhanced spreading rates of midocean ridges and produced higher growth rates of oceanic plateaus, both processes thus having contributed to a higher hydrothermal flux to the ocean. Oceanic and atm. redox states detd. the fate of this flux. When the hydrothermal flux overwhelmed the oceanic oxidn. state, iron was transported and deposited distally from hydrothermal vents. Where the hydrothermal flux was insufficient to overwhelm the oceanic redox state, iron was deposited only proximally, generally as oxides or sulfides. Manganese, in contrast, was more mobile. We conclude that occurrences of BIF, GIF, Phanerozoic ironstones, and exhalites surrounding VMS systems record a complex interplay inv

8.
Bolhar R. et al. A trace element and Pb isotopic investigation into the provenance and deposition of stromatolitic carbonates, ironstones and associated shales of the ?3.0Ga Pongola Supergroup, Kaapvaal Craton // Geochimica et Cosmochimica Acta. 2015. Vol. 158. P. 57–78.

Major and trace element, and Pb isotopic data for chemical and clastic sedimentary rocks of the Mesoarchaean Pongola Supergroup are employed to infer aspects of the provenance and depositional environment, including ambient seawater composition. Stromatolitic carbonates of the Nsuze Group were formed in a tidal-flat setting, whereas ironstones of the Mozaan Group were deposited in an outer-shelf setting during marine transgression. Geochemical criteria, employed to test for crustal contamination and diagenetic/metamorphic overprinting, demonstrate that carbonates and ironstones preserved their primary chemical signature. In comparison to other documented Precambrian stromatolites, shale-normalised REE+Y patterns for Nsuze carbonates show pronounced enrichment in middle REE, but lack strong elemental anomalies (La, Gd, Y) that are diagnostic for derivation from open marine waters. In contrast, normalised REE+Y for ironstones exhibit distinct positive La, Gd and Y anomalies. Both rock types are devoid of normalised Ce anomalies and show only minor enrichment in Eu, suggesting deposition in anoxic environments (with respect to the Ce3+/Ce4+ redox couple) accompanied by minor high-temperature hydrothermal input. Trace element geochemical data are most consistent with deposition of Nsuze carbonates in a shallow-water epicontinental basin with restricted but variable exchange to the open-ocean and dominant fluvial input, whereas ironstone precipitated in a deeper-water, epicontinental sea. Estuarine fractionation and organic complexation due to microbial activity is possibly indicated by MREE enrichment of the carbonates, also consistent with a restricted environment. Shales belonging to the Mozaan Group are characterised by high concentrations of Al and K relative to Ca, Na and Sr, indicative of pronounced in-situ weathering, coupled with K-metasomatism. The provenance is mixed, comprising (ultra)mafic and granitic source rocks.Pb isotope regression for Nsuze carbonates documents a widespread, tectono-thermal or fluid percolation event at around 2.4 Ga. Two-stage modelling of Pb isotope data, in association with published Sr and Nd isotope data, requires a source for Nzuse carbonates that was derived from evolved continental crust with an elevated U/Pb ratio (?-value) and an approximate crustal residence time of ?100–600 Ma.

9.
Chakhmouradian A.R., Smith M.P., Kynicky J. From “strategic” tungsten to “green” neodymium: A century of critical metals at a glance // Ore Geology Reviews. 2015. Vol. 64. P. 455–458.

The relative criticality of mineral commodities is evaluated using a wide range of parameters and in different contexts (e.g., from the standpoint of their importance to national security, or to a specific industrial application), which explains the multiplicity of classification schemes and variations in terminology applied to these commodities in the literature, media and government reports. The core group of critical metals, listed alphabetically, includes: antimony, beryllium, chromium, cobalt, gallium, germanium, indium, lithium, niobium, platinoids, rare-earth elements (REE, including yttrium), tantalum and tungsten. The present retrospect briefly describes the emergence of critical metals as a distinct resource type and the evolution of society's perception of these commodities over the past 100 years.

10.
Charlier B. et al. Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks // Earth-Science Reviews. 2015. Vol. 141. P. 56–81.

Magmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthosite–mangerite–charnockite–(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe–Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe–Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe–Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO2 variations. Post-cumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ± magnetite, ± apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe–Ti–P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe–Ti-enriched residual melts by filter-pressing and compaction, solid-state remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe–Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro- and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and with ballooning of the anorthosite diapir associated with gravitational sagging of dense ore bodies. Exploration perspectives show that oxide-apatite gabbronorites are interesting targets because ilmenite in these rocks is poorer in Cr and Mg, and because the Ti-resource may be combined with apatite and vanadiferous magnetite.

11.
Chen C. et al. The Whole-Rock Geochemical Composition of the Wudaogou Group in Eastern Yanbian, NE China-New Clues to Its Relationship with the Gold and Tungsten Mineralization and the Evolution of the Paleo-Asian Ocean: Geochemistry of Wudaogou Group, NE China // Resource Geology. 2015. Vol. 65, № 3. P. 232–248.

The late Paleozoic Wudaogou Group, one of the oldest metamorphic units in the eastern Yanbian area, has important tectonic and metallogenic significance. Here, we provide new insights into their protoliths, tectonic setting of the metamorphic rocks and their relationships with the gold and tungsten mineralization, using new petrog. and whole-?rock geochem. data for various lithologies within the Wudaogou Group. The protolith of the metamorphic rocks of the Wudaogou Group was intermediate-?basic volcanic rocks (e.g. basaltic andesite, trachyandesite, and basalt) and sedimentary rocks including argillaceous rocks, quartz sandstone, arkose and clayish graywacke, as well as pyroclastic sedimentary rock, covering tuffaceous sandstone. Before undergoing late Paleozoic epidote-?amphibolite facies regional metamorphism, these protoliths were formed during the middle-?late Permian in an island arc setting within a continental margin collage zone. Combined with the regional tectonic evolution, it can be speculated that the formation and the subsequent metamorphism of the protoliths of the metamorphic rocks from the Wudaogou Group were influenced by the change from subduction to collision of the Paleo-?Asian Ocean. Similarities of the rare earth element (REE) patterns and parameters among the metamorphic rocks within the Wudaogou Group, auriferous ores from the Xiaoxi'nancha gold (copper) deposit, and scheelites from the Yangjingou tungsten deposit, together with the favorable metallogenic element contents within the metamorphic rock series, imply that the Wudaogou Group could provide parts of metallic material for the gold and tungsten mineralization in the eastern Yanbian area, as exemplified by the Yangjingou deposit and Xiaoxi'nancha deposit, resp. Further, the metamorphic sedimentary rocks, esp. the metamorphic sandstones, quartz schists and quartz mica schists within the Wudaogou Group, have closer genetic relationships with the Yangjingou tungsten mineralization. However, the specific lithologies within this group which control the gold mineralization are still uncertain, and need further research.

12.U01624
Ciobanu C.L. et al. Gold-telluride nanoparticles revealed in arsenic-free pyrite // American Mineralogist. 2012. Vol. 97, № 8-9. P. 1515–1518.

Pyrite, the most abundant sulfide on Earth and a common component of gold deposits, can be a significant host for refractory gold. This is the first documentation of pore-attached, composite Au-telluride nanoparticles in “arsenic-free” pyrite. Trace elements mapping in pyrite from an intrusion-hosted Au deposit with orogenic overprint (Dongping, China) shows trails of tellurides overlapping Co-Ni-zonation. Intragranular microfracturing, anomalous anisotropy, and high porosity are all features consistent with devolatilization attributable to the orogenic event. The pyrite-hosted nanoparticles are likely the “frozen,” solid expression of Te-rich, Au-Ag-Pb-bearing vapors discharged at this stage. Nanoparticle formation, as presented here, provides the “smallest-scale” tool to fingerprint Au-trapping during crustal metamorphism

13.U12332
Cook N.J. et al. Minor and trace elements in bornite and associated Cu–(Fe)-sulfides: A LA-ICP-MS studyBornite mineral chemistry // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 21. P. 6473–6496.

In situ laser ablation inductively-coupled mass spectroscopy (LA-ICP-MS) has been used to provide a baseline dataset on the minor element contents in hypogene bornite and accompanying Cu-sulfides from 12 deposits with emphasis on syn-metamorphic Cu–vein systems in Norway, and skarn, porphyry and epithermal systems in SE Europe. Bornite contains significant concentrations of both Ag and Bi, especially in the vein and skarn deposits studied and has the potential to be a major Ag-carrier in such ores. Concentrations of up to >1 wt.% of both elements are documented. Measured concentrations appear to be independent of whether discrete Ag- and/or Bi-minerals are present within the analyzed sulfide. Where bornite and chalcocite (or mixtures of Cu-sulfides) coexist, Ag is preferentially partitioned into chalcocite over co-existing bornite and Bi is partitioned into the bornite. Bornite is a relatively poor host for Au, which mimics Ag by being typically richer in coexisting chalcocite. Most anomalous Au concentrations in bornite can be readily tracked to micron- and submicron-scale inclusions, but bornite and chalcocite containing up to 3 and 28 ppm Au in solid solution can be documented. Selenium and Te concentrations in bornite may be as high as several thousand ppm and correlate with the abundance of selenides and tellurides within the sample. Selenium distributions show some promise as a vector in exploration, offering the possibility to track a fluid source. Bornite and chalcocite are poor hosts for a range of other elements such as Co, Ni, Ga and Ge, etc. which have been reported to be commonly substituted within sulfides. Hypogene bornite and chalcocite may have significantly different trace element geochemical signatures from secondary (supergene) bornite.

14.U18998
Correale A. et al. A two-component mantle source feeding Mt. Etna magmatism: Insights from the geochemistry of primitive magmas // Lithos. 2014. Vol. 184-187. P. 243–258.

A review. The major elements, trace elements and Sr and Nd isotopes of selected Etnean primitive rocks (< 15 ky BP) were studied in order to characterize their mantle source. The noble-?gas geochem. of fluid inclusions in minerals from the same lavas was also investigated. The major element compns. of whole rocks and minerals showed that these products are among the most primitive at Mt. Etna, comprising 6.3-?17.5 wt.?% MgO. The variable LREE (Light Rare Earth Elements) enrichment relative to MORB (Mid-?Ocean Ridge Basalt) (Lan/Ybn = 11-?26)?, together with the patterns of certain trace-?element ratios (i.e., Ce?/Yb vs. Zr?/Nb and Th?/Y vs. La?/Yb)?, can be attributed to varying degrees of melting of a common mantle source. Numerical simulations performed with the MELTS program allowed the melting percentages assocd. with each product to be estd. This led us to recalc. the hypothetical parental trace-?element content of the Etnean mantle source, which was common to all of the investigated rocks. The characteristics of the Sr, Nd and He isotopes confirmed the primitive nature of the rocks, with the most-?depleted and primitive lava being that of Mt. Spagnolo (SPA; 143Nd?/144Nd = 0.512908 87Sr?/86Sr = 0.703317-?0.703325 and 3He?/4He = 7.6 Ra)?, and highlighted the similarity of the mantle sources feeding the volcanic activity of Mt. Etna and the Hyblean Plateau (a region to the south of Mt. Etna and characterized by older magmatism than Mt. Etna)?. The coupling of noble gases and trace elements suggests an origin for the investigated Etnean lavas from melting of a Hyblean-?like mantle, consisting of a two-?component source where a peridotitic matrix is veined by 10?% pyroxenite. A variable degree of mantle contamination by crustal-?like fluids, probably related to subduction, is proposed to explain the higher Sr-?isotope and lower Nd-?isotope values in some rocks (143Nd?/144Nd up to 0.512865 and 87Sr?/86Sr up to 0.703707)?. This process probably occurred in the source prior to magma generation, refertilizing some portions of the mantle. Accordingly, the estd. degree of melting responsible for each magma appears to be related to its 87Sr?/86Sr enrichment. In contrast, the decoupling between 3He?/4He and 87Sr?/86Sr ratios requires the occurrence in the crustal reservoirs of further processes capable of shifting the He isotope ratio towards slightly more radiogenic values, such as magma aging or a contribution of shallow fluid. Therefore, different residence times in the Etnean reservoir and?/or various rates of magma ascent could be key parameters for preserving the original He isotope marker of the Etnean mantle source.

15.
Deditius A.P. et al. The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits // Geochimica et Cosmochimica Acta. 2014. Vol. 140. P. 644–670.

The ubiquity of Au-?bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochem. behavior of Au and As in this sulfide occurs under a wide range of physico-?chem. conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-?ICP-?MS, SIMS, and ?-?PIXE analyses of As and Au in pyrite from Carlin-?type Au, epithermal Au, porphyry Cu, Cu-?Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS)?, Witwatersrand Au, iron oxide copper gold (IOCG)?, and coal deposits. Pyrite included in the data compilation formed under temps. from ?30 to ?600 °C and in a wide variety of geol. environments. The pyrite Au-?As data form a wedge-?shaped zone in compositional space, and the fact that most data points plot below the solid soly. limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-?bearing ore fluids that deposit this sulfide are mostly undersatd. with respect to native Au. The anal. data also show that the solid soly. limit of Au in arsenian pyrite defined by an Au?/As ratio of 0.02 is independent of the geochem. environment of pyrite formation and rather depends on the crystal-?chem. properties of pyrite and post-?depositional alteration. Compilation of Au-?As concns. and formation temps. for pyrite indicates that Au and As soly. in pyrite is retrograde; Au and As contents decrease as a function of increasing temp. from ?200 to ?500 °C. Based on these results, two major Au-?As trends for Au-?bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-?type and orogenic Au deposits where compns. are largely controlled by fluid-?rock interactions and?/or can be highly perturbed by changes in temp. and alteration by hydrothermal fluids. The second trend consists of pyrites from porphyry Cu and epithermal Au deposits, which are characterized by compns. that preserve the Au?/As signature of mineralizing magmatic-?hydrothermal fluids, confirming the role of this sulfide in controlling metal ratios in ore systems.

16.U08182
Dekov V.M. et al. Mineralogical and geochemical investigation of seafloor massive sulfides from Panarea Platform (Aeolian Arc, Tyrrhenian Sea) // Chemical Geology. 2013. Vol. 335. P. 136–148.

Panarea seafloor hydrothermal system is associated with a range of mafic to felsic volcanic rocks. The hydrothermal system is active at present and discharges magmatic–hydrothermal fluids and precipitates massive sulfides. The sulfides exhibit multi-stage deposition, evident in the alternation of several mineral generations that follow a general temporal precipitation sequence: marcasite > alunite > opal. Sr–Nd–Pb isotope data indicate that most of the metals in the sulfides are derived predominantly from the Panarea volcanic rocks with some contribution from ambient seawater and/or local sediments. A remarkable feature of these sulfides is their chondrite-normalized rare earth element (REEN) distribution pattern with a pronounced negative Eu anomaly, which has not been observed previously. Our study demonstrates that this REEN pattern reflects the REE fractionation during sulfide deposition. The ionic radius mismatch between Eu2 + (the main form of Eu in reduced, high-temperature hydrothermal fluids) and the only possible site for REE substitution in the marcasite, that of Fe2 +, suggests a crystallographic control on the REEN pattern. Apparently, marcasite precipitation can generate a sulfide deposit with a negative Eu anomaly due to discrimination against Eu2 + relative to REE3 + in the Fe2 + crystallographic site.

17.
Dostal J. et al. Cretaceous ongonites (topaz-bearing albite-rich microleucogranites) from Ongon Khairkhan, Central Mongolia: Products of extreme magmatic fractionation and pervasive metasomatic fluid: rock interaction // Lithos. 2015. Vol. 236-237. P. 173–189.

Ongonites were defined at their type locality at Ongon Khairkhan, central Mongolia, as pristine magmatic topaz-?bearing albite-?quartz-?keratophyres with up to 4 wt. % F and contg. phenocrysts of albite, K-?feldspar, quartz and rare mica and topaz hosted in a groundmass composed of the same minerals. However, detailed petrog. and SEM-?EDS studies indicate that these rocks underwent considerable subsolidus exchange with deuteric fluids, as evidenced by the presence of albitic plagioclase (Ab? 100) and end-?member orthoclase (Or? 100)?, secondary Li-?Fe-?rich mica (zinnwaldite) enriched in rare metals (Sn, W, Ta, Nb)?, pitted feldspars contg. fluid inclusions, and disseminated fluorite. The ? 120 Ma old dike rocks, emplaced at a high structural level in the crust, are strongly peraluminous leucogranites characterized by high Al and alkalis that are also enriched in Rb, Cs, Ga and Ta, depleted in Mg, Ca, Zr, Ba, Sr and Eu, and have anomalous K?/Rb, Rb?/Sr, Zr?/Hf and Nb?/Ta ratios compared to the av. continental crust. However, the suite has Nd isotopic ratios (?Nd(120)? ?- 1) similar to those of contemporaneous A-?type granites of the Mongolian-?Transbaikalian igneous province of the Central Asian Orogenic Belt. The inferred primary ?18O (?+ 6 to + 7‰) and Pb isotopic values are consistent with a granitic parent magma and interaction with orthomagmatic fluids. The ongonites and constituent minerals record (1) an extensive and protracted crystal fractionation history, in part due to the presence of volatiles (particularly F) which depressed the solidus temp. of the felsic rocks and extended its duration of crystn. and (2) subsolidus exchange with fluids which includes late flux of heated meteoric water as indicated by modified whole rock ?18O values (+ 0.5 to +2.7‰)?. The interaction of the ongonites with internally derived orthomagmatic fluids is considered to result in enrichment and?/or redistribution of several incompatible elements, but not to have greatly modified their original major element chem. which indicates that this suite represents the last stages of fractionation of a highly differentiated, F-?rich granitic magma. The escape of these evolved melts from the apical part of the underlying pluton is now represented by the ongonite dikes. Late-?stage magmatic, water-?rich fluids enriched in incompatible elements including Nb, Ta, Sn and W were responsible for the late- to post-?magmatic alteration and assocd. W mineralization.

18.
Du X., Graedel T.E. Global In-Use Stocks of the Rare Earth Elements: A First Estimate // Environmental Science & Technology. 2011. Vol. 45, № 9. P. 4096–4101.

Even though rare earth metals are indispensible in modern technology, very little quantitative information other than combined rare earth oxide extraction is available on their life cycles. We have drawn upon published and unpublished information from China, Japan, the United States, and elsewhere to estimate flows into use and in-use stocks for 15 of the metals: La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Here, we show that the combined flows into use comprised about 90 Gg in 2007; the highest for individual metals were ?28 Gg Ce and ?22 Gg La, the lowest were ?0.16 Gg Tm and ?0.15 Gg Lu. In-use stocks ranged from 144 Gg Ce to 0.2 Gg Tm; these stocks, if efficiently recycled, could provide a valuable supplement to geological stocks.

19.
Franchi F. et al. Differentiating marine vs hydrothermal processes in Devonian carbonatemounds using rare earth elements (Kess Kess mounds, Anti-Atlas, Morocco) // Chemical Geology. 2015. Vol. 409. P. 69–86.

Petrological and geochemical analyses were carried out on Early Devonian Kess Kess mound limestones of the Seheb el Rhassel Group exposed in the Hamar Laghdad Ridge (Tafilalt Platform, Eastern Anti-Atlas, Morocco) in order to evaluate marine vs hydrothermal processes for the origin of the mounds. Hydrothermal fluid circulation affected limestone deposition resulting in the formation of a plumbing system preserved in the mound facies and inter-mound facies as cavities, veins, and dykes. Shale-normalized rare earth element (REE) patterns for limestones display pronounced light REE depletion compared to middle REE (average PrSN / DySN = 0.46) and heavy REE (average PrSN / YbSN = 0.55), a super-chondritic Y/Ho ratio (up to 87) and positive La anomaly consistent with precipitation from normal marine seawater. Within our data set the Ce anomaly, as well as U and other trace element concentrations vary with facies providing evidence for variable redox conditions. The presence of positive Ce anomaly in carbonates of the plumbing system is consistent with precipitation under anoxic condition. Samples from mound facies and quartz veinlets in the upper part of the group show REE patterns consistent with precipitation from hydrothermal fluids. Early Devonian hypothetical seawater REE patterns were calculated from samples showing normal marine REE patterns (i.e. inter-mound facies) and from samples with weaker marine signature (i.e. fossiliferous mound limestones and plumbing system deposits). Hypothetical patterns are slightly enriched in ?REE compared to modern open ocean seawater. This study reveals that REE analysis is a powerful tool for understanding polygenetic carbonate systems. It sheds light into the genesis of the Kess Kess mounds by reconstructing fluid pathways and palaeo-redox conditions.

20.U12332
Frank M.R. et al. Gold and copper partitioning in magmatic-hydrothermal systems at 800°C and 100MPa // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 9. P. 2470–2482.

Porphyry-?type ore deposits sometimes contain fluid inclusion compns. consistent with the partitioning of copper and gold into vapor relative to coexisting brine at the depositional stage. However, this has not been reproduced exptl. at magmatic conditions. In an attempt to det. the conditions under which copper and gold may partition preferentially into vapor relative to brine at temps. above the solidus of granitic magmas, expts. were done at 800°, 100 MPa, oxygen fugacity (fO2sys) buffered by Ni-?NiO, and aS2sys fixed at either 3.5 ? 10-?2 by using intermediate solid soln.-?pyrrhotite, or 1.2 ? 10-?4 by using intermediate solid soln.-?pyrrhotite-?bornite. The coexisting vapor (?3 wt. % NaCl eq.) and brine (?68 wt. % NaCl eq.) were composed initially of NaCl + KCl + HCl + H2O, with starting HCl set to <1000 ?g?/g in the aq. mixt. Synthetic vapor and brine fluid inclusions were trapped at run conditions and subsequently analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-?ICP-?MS)?. The expts. demonstrate that copper and gold partitioned strongly into the magmatic volatile phase(s) (MVP) (i.e., vapor or brine) relative to a silicate melt over the entire imposed range of aS2sys. Nernst style partition coeffs. between coexisting brine (b) and melt (m)?, Db?/m (±1?)?, range from 3.6(±2.2) ? 101 to 4(±2) ? 102 for copper and from 1.2(±0.6) ? 102 to 2.4(±2.4) ? 103 for gold. Partition coeffs. between coexisting vapor (v) and melt, Dv?/m range from 2.1 ± 0.7 to 18 ± 5 and 7(±3) ? 101 to 1.6(±1.6) ? 102 for copper and gold, resp. Partition coeffs. for all expts. between coexisting brine and vapor, Db?/v (±1?)?, range from 7(±2) to 1.0(±0.4) ? 102 and 1.7(±0.2) to 15(±2) for copper and gold, resp. Obsd. av. Db?/v at an aS2sys of 1.2 ? 10-?4 were elevated, 95(±5) and 15 ± 1 for copper and gold, resp., relative to those at the higher aS2sys of 3.5 ? 10-?2 where Db?/v were 10(±5) for copper and 7(±6) for gold. Thus, there is an inverse relationship between the aS2sys and the Db?/v for both copper and gold with increasing aS2sys resulting in a decrease in the Db?/v signifying increased importance of the vapor phase for copper and gold transport. This suggests that copper and gold may complex with volatile S-?species as well as Cl-?species at magmatic conditions, however, none of the expts. at 800 °C and 100 MPa had a Db?/v ? 1. Speciation was not directly detd., but the existence is inferred of some metal-?sulfur complexes, based on the reported data. Copper and gold may partition preferentially into the brine in most instances at or above the wet solidus. However, in most systems, the mass of vapor is greater than the mass of brine, and vapor transport of copper and gold may become more important in the magmatic environment at higher aS2sys, lower fO2sys, or near the crit. point in a salt-?water system. A Db?/v ? 1 at subsolidus hydrothermal conditions may also occur in response to changes in temp., fO2sys, aS2sys, and?/or acidity. Addnl., both copper and gold were obsd. to partition into intermediate solid soln. and bornite much more strongly than into vapor, brine or silicate melt. This suggests that, although vapor and brine are both efficient at removing copper and gold from a silicate melt, the presence of Cu-?Fe sulfides can sequester a substantial portion of the copper and gold contained within a silicate melt if the Cu-?Fe sulfides are abundant.

21.U09363
Fu B. et al. New constraints on fluid sources in orogenic gold deposits, Victoria, Australia // Contributions to Mineralogy and Petrology. 2012. Vol. 163, № 3. P. 427–447.

Fluid inclusion microthermometry, Raman spectroscopy and noble gas plus halogen geochem., complemented by published stable isotope data, have been used to assess the origin of gold-?rich fluids in the Lachlan Fold Belt of central Victoria, south-?eastern Australia. Victorian gold deposits vary from large turbidite-?hosted orogenic' lode and disseminated-?stockwork gold-?only deposits, formed close to the metamorphic peak, to smaller polymetallic gold deposits, temporally assocd. with later post-?orogenic granite intrusions. Despite the differences in relative timing, metal assocn. and the size of these deposits, fluid inclusion microthermometry indicates that all deposits are genetically assocd. with similar low-?salinity aq., CO2-?bearing fluids. The majority of these fluid inclusions also have similar 40Ar?/36Ar values of less than 1500 and 36Ar concns. of 2.6-?58 ppb (by mass) that are equal to or much greater than air-?satn. levels (1.3-?2.7 ppb)?. Limited amts. of nitrogen-?rich fluids are present at a local scale and have the highest measured 40Ar?/36Ar values of up to 5,?700, suggesting an external or distinct source compared to the aq. fluids. The predominance of low-?salinity aq.-?carbonic fluids with low 40Ar?/36Ar values, in both orogenic' and intrusion-?related' gold deposits, is attributed to fluid prodn. from common basement volcano-?sedimentary sequences and fluid interaction with sedimentary cover rocks (turbidites)?. Aq. fluid inclusions in the Stawell-?Magdala deposit of western Victoria (including those assocd. with N2) preserve mantle-?like Br?/Cl and I?/Cl values. In contrast, fluid inclusions in deposits in the eastern structural zones, which contain more abundant shales, have elevated molar I?/Cl ratios with max. values of 5,?170 ? 10-?6 in the Melbourne Zone. Br?/I ratios in this zone range from 0.5 to 3.0 that are characteristic of fluid interaction with org.-?rich sediments. The max. I?/Cl and characteristic Br?/I ratios provide evidence for org. Br and I released during metamorphism of the shales. Therefore, the regional data provide strong evidence for the involvement of sedimentary components in gold mineralization, but are consistent with deeper metamorphic fluid sources from basement volcano-?sedimentary rocks. The overlying sediments are probably involved in gold mineralization via fluid-?rock interaction.

22.U12510
Gaboury D. Does gold in orogenic deposits come from pyrite in deeply buried carbon-rich sediments?: Insight from volatiles in fluid inclusions // Geology. 2013. Vol. 41, № 12. P. 1207–1210.

The origin of volatiles in fluid inclusions was reviewed for testing the involvement at depth of carbonaceous-pyritic sedimentary rocks as the source for orogenic gold mineralization. Fluid inclusions from selected deposits were analyzed by solid-probe mass spectrometry. Fluids are mostly aqueous-carbonic, with variable amounts of N2, CH4, C2H6, Ar, H2S, H2 and He. For fluids with CH4 and C2H6, their ratios (C1/C2) range from 2.6 to 25.5, indicating that C2H6 is sourced from thermally degraded organic matter. Proportions of CO2, CH4, C2H6 and H2 are highly variable and can be explained by hydrothermal reactions where C2H6 is degraded to CO2 by water consumption. Such reactions may account for the problematic CO2-rich, H2O-poor fluids associated with some of the richest gold districts. Conditions needed for C2H6 degradation are also fundamental for forming gold deposits, such as HS--enriched fluids for carrying gold and local weakly oxidizing conditions for promoting gold precipitation. The C2H6 content is recorded in fluids from Mesoarchean to Cretaceous gold deposits, providing support for a general model where fluids and gold were sourced from deeply buried, carbonrich, and pyrite-gold-bearing sedimentary rocks.

23.
Gloser S. et al. Raw material criticality in the context of classical risk assessment // Resources Policy. 2015. Vol. 44. P. 35–46.

The rapid economic development of emerging countries in combination with an accelerating spread of new technologies has led to a strongly increasing demand for industrial metals and minerals regarding both the total material requirement and the diversity of elements used for the production of specific high-tech applications. Several minor metal markets which are often characterized by high market concentrations of raw material production at the country and the company level have shown high turbulences since the beginning of the 21st century. This has led to growing concerns about the security of raw material supply, particularly in established western economies. As a result, numerous studies on supply risks and raw material criticality for different countries and regions were carried out recently. In this paper, we discuss the methodology of raw material criticality assessment within a criticality matrix which is a modification of a classical risk matrix. Therefore, we first provide an overview of the approaches and results of major studies quantifying raw material criticality by means of a criticality matrix. By applying a uniform scaling to the matrices of different recent studies, a direct comparison of results and data interpretation was enabled. As shown in this paper, the close relation between the criticality matrix and classical risk analysis within a risk matrix was overlooked in most studies which may lead to misunderstanding and misinterpretation of the results. We posit that the interpretation of the coordinates within the criticality matrix and the thresholds separating critical and non-critical raw materials need to be revised by means of general risk definitions.

24.
Goldfarb R.J., Groves D.I. Orogenic gold: Common or evolving fluid and metal sources through time // Lithos. 2015. Vol. 233. P. 2–26.

Orogenic gold deposits of all ages, from Paleoarchean to Tertiary, show consistency in chem. compn. They are the products of aq.-?carbonic fluids, with typically 5-?20 mol?% CO2, although unmixing during extreme pressure fluctuation can lead to entrapment of much more CO2-?rich fluid inclusions in some cases. Ore fluids are typically characterized by significant concns. of CH4 and?/or N2, common ests. of 0.01-?0.36 mol?% H2S, a near-?neutral pH of 5.5, and salinities of 3-?7 wt.?% NaCl equiv., with Na > K > > Ca,?Mg. This fluid compn. consistency favors an ore fluid produced from a single source area and rules out mixing of fluids from multiple sources as significant in orogenic gold formation. Nevertheless, there are broad ranges in more robust fluid-?inclusion trapping temps. and pressures between deposits that support a model where this specific fluid may deposit ore over a broad window of upper to middle crustal depths.Much of the reported isotopic and noble gas data is inconsistent between deposits, leading to the common equivocal interpretations from studies that have attempted to define fluid and metal source areas for various orogenic gold provinces. Fluid stable isotope values are commonly characterized by the following ranges: (1) ?18O for Precambrian ores of + 6 to + 11‰ and for Phanerozoic ores of + 7 to + 13‰; (2) ?D and ?34S values that are extremely variable; (3) ?13C values that range from - 11 to - 2‰; and (4) ?15N of + 10 to + 24‰ for the Neoarchean, + 6.5 to + 12‰ for the Paleoproterozoic, and + 1.5 to + 10‰ for the Phanerozoic. Secular variations in large-?scale Earth processes appear to best explain some of the broad ranges in the O, S, and N data. Fluid:rock interaction, particularly in ore trap areas, may cause important local shifts in the O, S, and C ratios. The extreme variations in ?D mainly reflect measurements of hydrogen isotopes by bulk extn. of waters from numerous fluid inclusion generations, many which are not related to ore formation. Radiogenic isotopes, such as those of Pb, Sr, Nd, Sm, and Os, measured on hydrothermal minerals are even more difficult to interpret for defining metal source, particularly as the low-?salinity ore fluids transport limited amts. of these elements and significant amts. of these may be locally added to the minerals during alteration reactions at the sites of gold deposition. Noble gas and halogen data are equally equivocal.Fluid exsoln. from granitoids emplaced into the upper and middle crust, metamorphism of the crust, or fluids entering trans-?crustal fault zones from below the crust all remain as permissive scenarios assocd. with orogenic gold formation, as the abundant geochem. data are equivocal. However, geol. and geochronol. data weigh heavily against a magmatic-?hydrothermal model in the upper to middle crust. There is no universal temporal assocn. between orogenic gold and magmatism, and where there is an overlap in age, there is no specific type of magmatism consistently assocd. with gold formation, nor element zonation around any specific pluton. A crustal metamorphic model for fluid and metal sources is very consistent with geol., geochronol., and geochem. data, although metamorphism on a regional scale that releases these components into major fault zones can be assocd. with many processes along active continental margins. These can include crustal thickening and radiogenic heating, slab rollback and heating during crustal extension, or subduction of a spreading ridge heating the base of an accretionary prism. In rare examples where Phanerozoic orogenic gold deposits are hosted in Precambrian high-?grade metamorphic terranes, fluids and metals must, however, enter a transcrustal fault system from a sub-?crustal source. This could either be a devolatilized, subducted, relatively flat, perhaps stalled slab and its overlying sediment, or the corner of the fertilized mantle wedge that releases a fluid during a thermal event.

25.
Golev A. et al. Rare earths supply chains: Current status, constraints and opportunities // Resources Policy. 2014. Vol. 41. P. 52–59.

"The unique properties of rare earth elements (REEs) and lack of alternatives for their application in modern technologies, especially electronics and fast growing green technologies such as renewable energy generation and storage, energy efficient lights, electric cars, and auto catalysts, as well as specific military and aerospace applications, underpin their strategic status. The absolute domination of China in the production of REEs, aggravated by a significant reduction in export quotas since 2010, raised severe concerns of securing REE supply in the USA, Japan, European Union and other countries. In 2010–2012 it resulted in skyrocketing prices and supply deficit for most REEs, leading to numerous new REE start-up companies around the world, with allocation of large investments in additional geological explorations and technology development. At the same time, the supply difficulties enforced the downstream users of REEs to invest in the development of recycling technologies and reuseoptions for these elements. The main focus of this paper is to overview existing and emerging REE supply chains outside of China up to date (end of 2013), define their environmental constraints and opportunities, as well as reflect on a broader range of technical, economic, and social challenges for both primary production and recycling of REEs. A better understanding of these factors could help to optimize the supply chain of virgin and recycled rare earths, minimise the environmental impacts arising from their processing, and be used as a prototype for a broader range of critical metalsand commodities."

26.U18998
Gonzalez-Jimenez J.M. et al. Chromitites in ophiolites: How, where, when, why? Part II. The crystallization of chromitites // Lithos. 2014. Vol. 189. P. 140–158.

A review of previous work relevant to the formation of concns. of chromite in peridotites from ophiolitic (s.l.) sequences highlights some of the key problems in understanding the complex processes involved. This review forms the basis for chromitite-?genesis models that integrate new geochem. data with petrol., field and microstructural observations, and for a re-?interpretation of previous data and concepts. The geochem. data include major- and trace-?element contents of chromite and coexisting phases and esp. the nature and Os-?isotope compns. of platinum-?group minerals (PGM) and base-?metal sulfides (BMS)?; the PGM data in particular provide new insights into chromitite formation.Differences in the morphol., structural relationships, and geochem. signatures of chromitites allow the recognition of three distinct types. Type I is the most abundant and is distinguished by bulk-?rock enrichment in Os, Ir and Ru relative to Rh, Pt, and Pd; it shows no consistent spatial location within the ophiolite "stratigraphy". The second type (Type IIA) is generally confined to the shallower zones of the oceanic lithosphere (mainly as concordant layers, bands and seams, but also as discordant pods or irregular bodies)?, and is significantly enriched in the incompatible platinum-?group elements (PGE) with generally higher total PGE contents than Type I. The third type (Type IIB) shows the same spatial distributions and PGE patterns as Type IIA but has a more limited range of Cr# and a wider range of Mg# that overlap with the compositional range of chromites from layered mafic intrusions.Reaction of melts with peridotite wall-?rocks results in the extn. of pyroxene into the melts, forming anastomosing dunitic melt channels in the mantle sections of ophiolites. The Os-?isotope heterogeneity in PGMs within single chromitite samples, as described in Part I, provides clear evidence that melt mingling take place on very small scales. This suggests that ophiolitic chromitites are generated through the disequil. pptn. of chromite, forced by small-?scale mingling of melts that had different SiO2 contents, reflecting derivation from different source rocks, different degrees of partial melting and?/or wall-?rock reaction. Progressive reaction, crystn. and mixing of melts within the channel system assures the presence of a spectrum of melts at any one time, making the system self-?sustaining; each new injection of mafic melt would find more evolved melts with which to react, producing more chromite. Chromite is carried to its final deposition by migration of the chromite-?bearing melts, or fluids derived from them. This explains the general assocn. of chromitite with the dunitic portions of ophiolitic mantle; dunite margins around chromite segregations represent the original host rock intruded by chromitite-?forming fluids.

27.U09363
Gonzalez-Jimenez J.M. et al. Significance of ancient sulfide PGE and Re–Os signatures in the mantle beneath Calatrava, Central Spain // Contrib Mineral Petrol. 2014. Vol. 168, № 2. P. 1047.

Spinel lherzolite and wehrlite xenoliths from the Cenozoic Calatrava volcanic field carry the geochemical imprint of metasomatic agents that have affected the subcontinental lithospheric mantle beneath Central Iberia. Some xenoliths (mainly wehrlites) were enriched in REE, Sr, P, and CO2 by silicic-carbonate-rich metasomatic melts/fluids, while others record the effects of subduction-related hydrous silicate fluids that have precipitated amphibole and induced high Ti/Eu in primary clinopyroxene. The petrographic observations and geochemical data suggest that interstitial glass in the xenoliths represent the quenched products of Si-rich melts that infiltrated the mantle peridotite shortly before the entrainment of the xenoliths in the host magmas that erupted ca 2 million years ago. During their infiltration, the metasomatic melts reacted with peridotite, resulting in silica enrichment, while remobilizing grains of iron-rich monosulfide solid solution (Fe-rich Mss) initially enclosed in, or intergranular to, primary olivine and pyroxenes. In situ laser ablation inductively coupled plasma-mass spectrometry analysis of single sulfide grains reveals that the Fe-rich Mss in glass shows platinum-group element (PGE) patterns and 187Os/188Os compositions identical to the Fe-rich Mss occurring as inclusions in, or at grain boundaries of primary silicates. Moreover, independent of its microstructural position, Fe-rich Mss exhibits PGE and 187Os/188Os signatures typical of Mss either residual after partial melting or crystallized directly from sulfide melts. Our findings reveal that young metasomatic melt(s)/fluid(s) may carry remobilized sulfides with PGE and Os-isotopic signatures identical to those of texturally older sulfides in the peridotite xenolith. These sulfides thus still provide useful information about the timing and nature of older magmatic events in the subcontinental mantle.

28.
Harper E.M. et al. The criticality of four nuclear energy metals // Resources Conservation and Recycling. 2015. Vol. 95. P. 193–201.

Concerns about the future balance between the supply and demand of metals have inspired research to define and assess metal criticality. Here we apply a comprehensive criticality methodology to four metals with uses in nuclear energy: zirconium (Zr), hafnium (Hf), thorium (Th), and uranium (U). 2008 criticality assessments for these metals were made on the national level for the United States and on the global level. The results and uncertainty estimates in three-dimensional "crificality space" are comprised of supply risk (SR), vulnerability to supply restriction (VSR), and environmental implications (El) axes. The SR score is the highest for zirconium over both the medium term (i.e., 5-10 years) and the long term (i.e., a few decades). The cradle-to-gate El score is highest for uranium, followed by hafnium and then thorium, with impacts due to a combination of on-site emissions and upstream burdens from the use of energy and materials during mineral processing and refining. Uranium has the highest VSR score at the national level, and the second highest at the global level. Zirconium is the most vulnerable at the global level. In general, SR for the four metals are reasonably high for the United States and more moderate for the planet, while El and VSR scores are low to moderate. Overall, the criticality of the metals analyzed appears not to be of high concern, either nationally or globally.

29.
Heimann A. et al. Geochemistry and genesis of low-grade metasediment-hosted Zn–Pb–Ag mineralization, southern Proterozoic Curnamona Province, Australia // Journal of Geochemical Exploration. 2013. Vol. 128. P. 97–116.

Sediment-?hosted, Paleoproterozoic low-?grade Zn-?Pb-?Ag and Cu-?Au mineralization occurs at the Polygonum, Thunderdome, Hunters Dam, and Benagerie Ridge prospects under a thick sedimentary cover in the Mulyungarie Domain (MD) of the southern Curnamona Province (SCP)?, Australia. Host rocks and mineralization were metamorphosed to lower greenschist facies at Benagerie Ridge, upper greenschist facies at Hunters Dam, and lower to upper amphibolite facies at Polygonum and Thunderdome. The giant Paleoproterozoic Pb-?Zn-?Ag Broken Hill deposit, which was metamorphosed to the granulite facies, is hosted in the Broken Hill Domain (BHD)?. The general lithostratigraphy for each prospect is similar and can be subdivided into four main units. Unit 1, at the base of the stratigraphic section, hosts Cu-?Au mineralization and is characterized by the presence of oxidized magnetic metapsammopelites. Unit 2 consists of sulfide-?rich, pyritic carbonaceous metapelites, calcareous metashales?/siltstones, Mn-?bearing sideritic metacarbonates, metacalc-?silicates, and carbonate and feldspar lenses and layers. Syn-?sedimentary sulfide mineralization occurs as laminations of fine-?grained pyrite and sphalerite and resembles that at the HYC deposit, Queensland. Differences in ?13C values (?13CVPDB = - 10.2 and - 0.8‰) of calcite in unit 2 from the same area suggest variable amts. of original org. C. The ?13C values of carbonates in Broken Hill ore and those obtained here from the Esmeralda deposit near Broken Hill are extremely low (?13C = - 25 to - 21‰) and likely resulted from volatilization and high temp. effects during high-?grade metamorphism. Barren laminated carbonaceous metapelites in unit 3 constitute a marker unit throughout the SCP. Unit 4 at the top of the stratigraphic sequence consists of psammopelitic and laminated andalusite or chiastolite phyllites that contain garnet and gahnite, laminated garnetite, quartz garnetite, Mn-?bearing banded iron formation, amphibolite, and stratabound hydrothermal Pb-?Zn mineralization. This unit, which is present at the Polygonum and Thunderdome prospects, is stratigraphically equiv. to the upper Broken Hill Group, which hosts the Broken Hill deposit. Base metals occur in metacarbonates and metapelites and close to redox boundaries between units 1 and 2, and units 2 and 3. Geochem. indicators of stratabound Pb-?Zn mineralization in the northern part of the SCP include whole-?rock values of > 4 ppm Tl, > 25 ppm Cd, and > 17 ppm Se in units 2 and 4, (Mn + Fe + Mg)?/(Mn + Fe + Mg + Ca) ratios > 0.9 for carbonates, Mn?/(Mn + Fe + Mg) ratios > 0.6 for garnet in garnet-?quartz rocks, and Mn?/(Mn + Ca + Fe) ratios > 0.3 for garnet in metacalc-?silicate rocks.

30.
Helmy H.M. et al. Noble metal nanoclusters and nanoparticles precede mineral formation in magmatic sulphide melts // Nature Communications. 2013. Vol. 4. Article № 2405.

In low temperature aqueous solutions, it has long been recognized by in situ experiments that many minerals are preceded by crystalline nanometre-sized particles and non-crystalline nanophases. For magmatic systems, nanometre-sized precursors have not yet been demonstrated to exist, although the suggestion has been around for some time. Here we demonstrate by high temperature quench experiments that platinum and arsenic self-organize to nanoparticles, well before the melt has reached a Pt-As concentration at which discrete Pt arsenide minerals become stable phases. If all highly siderophile elements associate to nanophases in undersaturated melts, the distribution of the noble metals between silicate, sulphide and metal melts will be controlled by the surface properties of nano-associations, more so than by the chemical properties of the elements.

31.U01624
Hettmann K. et al. Thallium geochemistry in the metamorphic Lengenbach sulfide deposit, Switzerland: Thallium-isotope fractionation in a sulfide melt // American Mineralogist. 2014. Vol. 99, № 4. P. 793–803

The Lengenbach (Switzerland) Pb-?As-?Tl-?Zn deposit was formed from a sulfide melt at about 500 °C during Alpine metamorphism, but details on its formation and esp. the source of the metals are still under debate. In this study we present two sample sets to address these questions:. (1) MC-?ICP-?MS analyses of thallium isotopes in sulfides, sulfosalts, and melt inclusions from the Alpine metamorphic Lengenbach deposit in the Binn Valley of Switzerland, the non-?metamorphic Wiesloch Mississippi Valley-?type deposit in Southern Germany, and the Cu- and As-?rich mineralization at Pizzo Cervandone about 2 km SW of the Lengenbach deposit, which has been discussed as potential source of the Lengenbach metals. (2) LA-?ICP-?MS analyses of micas from the Lengenbach deposit and surrounding country rocks between the deposit and the Pizzo Cervandone to trace potential metal-?bearing fluid pathways. We found that Tl isotope compns. expressed as ?205Tl values in all investigated samples range from -?4.1 ± 0.5 to +1.9 ± 0.5. The whole variation can be seen in the Lengenbach deposit alone, which hence records considerable fractionation even during high-?temp. processes involving a sulfide melt. This large range of ?205Tl is thought to be caused by nuclear vol.-?dependent fractionation. Interestingly, the common fahlores at Lengenbach behave differently from all other investigated sulfosalts: based on their heavy isotopic compn. together with a low As?/S-?ratio, they do not seem to be crystd. from the sulfide melt, but are interpreted to have formed from hydrothermal fluids enriched in the heavy Tl isotopes. Although As mobilization in the gneisses and dolomites surrounding the Lengenbach deposit is evident based on secondary arsenites, no traces of such a country rock fluid could be found in fissure micas at Lengenbach. Hence, considerations involving K?/Rb, Rb?/Tl, As?/S, and Pb?/Tl ratios in the sulfides and micas imply that the element enrichment in the Lengenbach deposit is either pre-?Alpine or related to peak metamorphism, but occurred definitely before mica growth at Lengenbach.

32.
Hofstra A.H. et al. Fluid inclusion evidence for a genetic link between simple antimony veins and giant silver veins in the Coeur d’Alene mining district, ID and MT, USA // Geofluids. 2013. Vol. 13, № 4. P. 475–493.

The US Antimony mine in west central Montana is the United States' second largest quartz-?stibnite vein deposit with prodn. and reserves of about 15.4 kt of antimony. It is in the Mesoproterozoic Belt Basin on the eastern side of the Coeur d'Alene mining district that is known for its world class Ag, Pb, and Zn veins. To advance understanding of the origin and relation of the simple quartz-?stibnite veins in the Prichard Formation to the giant Ag-?rich tetrahedrite veins in the Revett and St. Regis Formations, fluid inclusions in quartz from the US Antimony mine were characterized using a variety of single inclusion and bulk anal. techniques. The measured Sb concns. in fluid inclusions (approx. 2000 ppm) agree with equil. models for stibnite-?satd. fluids at the measured homogenization temps. (224-?263°C)?, salinities (approx. 5 wt.?% NaCl)?, H2S concns. (<0.001 mol?%)?, and near neutral pH indicated by sericitic alteration. The aq.-?carbonic fluid inclusions in quartz from the US Antimony mine have P-?T-?X that are similar to previous results on fluid inclusions from the giant silver veins in the district. The assemblage and abundance of trace elements and ore metals (Sb > As > Fe > Pb > Zn > Cu > Ag) in fluid inclusions from the US Antimony mine support previous interpretations, based upon Pb isotopes, that the quartz-?stibnite veins are genetically related to the Ag-?rich tetrahedrite veins. In particular, the measured range of Ag concns. in US Antimony fluid inclusions brackets that calcd. on the basis of equil. with tetrahedrite in the silver veins. These data clearly show that hydrothermal fluids in the Prichard Formation contained metals that were fixed at shallower levels in the Revett and St. Regis Formations. We surmise that both the antimony and silver veins formed in response to Cretaceous magmatism, prograde metamorphism of the lower Prichard Formation, and episodic discharge of metamorphic fluids along dilatant faults. Ascending fluids deposited quartz and stibnite in the upper Prichard Formation and siderite, quartz, and tetrahedrite at shallower levels in the Revett and St. Regis Formations in response to cooling, decompression, phase sepn., and mixing with external fluids.

33.
Hu F.F. et al. Fluid inclusions at different depths in the Sanshandao gold deposit, Jiaodong Peninsula, China // Geofluids. 2013. Vol. 13, № 4. P. 528–541.

The Sanshandao gold deposit, located at northwestern edge of the Jiaodong Peninsula, eastern North China Craton, is one of the largest gold deposits in the Jiaodong gold province. In the deposit, disseminated- and stockwork-?style ores are hosted in Mesozoic granitoids. Mineralization and alteration are largely controlled by the regional Sanshandao-?Cangshang fault. Sericite sepd. from alteration rocks in the mineralized zone yields an Rb-?Sr isochron age of 117.6 ± 3.0 Ma. The ore-?forming fluids in the Sanshandao gold deposit contain CO2-?H2O-?NaCl±CH4 with low to intermediate temps. and low salinities. Microthermometric anal. shows that homogenization temps. gradually decrease from the early mineralizing stage (258-?416°C) to main mineralizing stage (180-?321°C) and to late mineralizing stage (112-?231°C)?. Homogenization temps. from the same mineralizing stage are nearly same and do not show an increase with depth. The nature of the ore-?forming fluids remains nearly the same over a 2000 m vertical depth interval.

34.U1045X
Huston D.L. et al. The Geology and Metallogeny of Volcanic-Hosted Massive Sulfide Deposits: Variations through Geologic Time and with Tectonic Setting // Economic Geology. 2010. Vol. 105, № 3. P. 571–591.

Anal. of metallogenic data, including grade and tonnage, host-?rock succession, ore and alteration mineralogy, and lead and sulfur isotope data, indicates significant secular changes in the character of volcanic-?hosted massive sulfide (VHMS) deposits, which appear to be related to changes in tectonic processes, tectonic cycles, and changes in the compn. of the hydrosphere and atm. The distribution of these deposits, whether measured in no. of deposits, tons of ore, or tons of metal, is episodic, with major peaks at 2740 to 2690, 1910 to 1840, 510 to 460, and 390 to 355 Ma. These peaks correspond to the assembly of major continental land masses, including Kenorland, Nuna, Gondwana, and Pangea, resp. Periods when fewer VHMS deposits formed correspond to periods of supercontinent and?/or supercraton stability. The VHMS deposits do not form during supercontinent and?/or supercraton breakup; rather, these intervals are assocd. with deposition of clastic-?dominated sediment-?hosted zinc-?lead deposits. The main exception to these generalizations is the amalgamation of Rodinia, which was not accompanied by significant VHMS formation. Rodinian amalgamation may have been dominated by advancing accretionary orogenesis, whereby the over-?riding plate did not go into extension. In this case, slab rollback and the assocd. extension to form back-?arc basins would not have been common, a setting typically conducive to the formation and preservation of VHMS deposits. Large ranges in source 238U?/204Pb (?) that characterized VHMS deposits in the Archean and Proterozoic indicate early (Hadean to Paleoarchean) differentiation of the Earth. A progressive decrease in ? variability may indicate homogenization with time of these differentiated sources. Secular increases in the amt. of lead and decreases in 100Zn?/(Zn+Pb) relate to an increase in felsic rock-?dominated successions as hosts to deposits and to an apparent abs. increase in the abundance of lead in the crust with time. The increase in the abundance of barite and other sulfate minerals in VHMS deposits, from virtually absent in the Mesoarchean and Neoarchean to relatively common in the Phanerozoic, relates to the progressive oxidn. of the atm. and hydrosphere. The total sulfur content of the oceans also increased, resulting in the enhanced importance of seawater sulfur in VHMS ore fluids with time. In Archean to Paleoproterozoic deposits, the bulk of the sulfur was derived by leaching rocks underlying the deposits, with little contribution from seawater, resulting in uniform, near-?zero per mil values of ?34Ssulfide. In contrast, the more variable ?34Ssulfide values of younger deposits reflect the increasing importance of seawater sulfur in the hydrothermal systems. Unlike Mesoarchean and Neoarchean deposits, Paleoarchean deposits contain abundant barite. This sulfate is inferred to have been derived from photolytic decompn. of atm. SO2 and does not reflect overall oxidized oceans. Archean and Proterozoic seawater was significantly more saline than that in the Phanerozoic, particularly upper Phanerozoic seawater. The VHMS ore fluids reflect this, being on av. more saline in Archean and Proterozoic deposits. This variability introduces uncertainty into genetic models advocating brine pools or magmatic-?hydrothermal contributions based on high-?salinity ore fluids.

35.U12332
Ingham E.S. et al. A combined chemical, isotopic and microstructural study of pyrite from roll-front uranium deposits, Lake Eyre Basin, South Australia // Geochimica et Cosmochimica Acta. 2014. Vol. 125. P. 440–465.

The common sulfide mineral pyrite is abundant throughout sedimentary uranium systems at Pepegoona, Pepegoona West and Pannikan, Lake Eyre Basin, South Australia. Combined chem., isotopic and microstructural anal. of pyrite indicates variation in fluid compn., sulfur source and pptn. conditions during a protracted mineralization event. The results show the significant role played by pyrite as a metal scavenger and monitor of fluid changes in low-?temp. hydrothermal systems. In-?situ micrometer-?scale sulfur isotope analyses of pyrite demonstrated broad-?scale isotopic heterogeneity (?34S = -?43.9 to +32.4‰VCDT)?, indicative of complex, multi-?faceted pyrite evolution, and sulfur derived from more than a single source. Preserved textures support this assertion and indicate a genetic model involving more than one phase of pyrite formation. Authigenic pyrite underwent prolonged evolution and recrystn., evidenced by a genetic relationship between archetypal framboidal aggregates and pyrite euhedra. Secondary hydrothermal pyrite commonly displays hyper-?enrichment of several trace elements (Mn, Co, Ni, As, Se, Mo, Sb, W and Tl) in ore-?bearing horizons. Hydrothermal fluids of magmatic and meteoric origins supplied metals to the system but the geochem. signature of pyrite suggests a dominantly granitic source and also the influence of mafic rock types. Irregular variation in ?34S, coupled with oscillatory trace element zonation in secondary pyrite, is interpreted in terms of continuous variations in fluid compn. and cycles of diagenetic recrystn. A late-?stage oxidizing fluid may have mobilized selenium from pre-?existing pyrite. Subsequent restoration of reduced conditions within the aquifer caused ongoing pyrite re-?crystn. and pptn. of selenium as native selenium. These results provide the first qual. constraints on the formation mechanisms of the uranium deposits at Beverley North. Insights into depositional conditions and sources of both sulfide and uranium mineralization and an improved understanding of pyrite geochem. can also underpin an effective vector for uranium exploration at Beverley North and other sedimentary systems of the Lake Eyre Basin, as well as in comparable geol. environments elsewhere.

36.U12332
Jego S., Pichavant M., Mavrogenes J.A. Controls on gold solubility in arc magmas: An experimental study at 1000°C and 4kbar // Geochimica et Cosmochimica Acta. 2010. Vol. 74, № 7. P. 2165–2189.

In order to (1) explain the worldwide assocn. between epithermal gold-?copper-?molybdenum deposits and arc magmas and (2) test the hypothesis that adakitic magmas would be Au-?specialized, the soly. was detd. of Au at 4 kbar and 1000 °C for three intermediate magmas (two adakites and one calc-?alk. compn.) from the Philippines. The expts. were performed over a fO2 range corresponding to reducing (?NNO-?1, where NNO refers to the Ni-?NiO fugacity buffer)?, moderately oxidizing (?NNO+1.5) and strongly oxidizing (?NNO+3) conditions as measured by solid Ni-?Pd-?O sensors. They were carried out in gold containers, the latter serving also as the source of gold, in presence of variable amts. of H2O and, in a few addnl. expts., of S. Concns. of Au in glasses were detd. by laser ablation ICP mass spectroscopy. Gold soly. in melt is very low (30-?240 ppb) but increases with fO2 in a way consistent with the dissoln. of gold as both Au1+ and Au3+ species. In the S-?bearing expts. performed at ?NNO-?1, gold soly. reaches much higher values, from ?1200 to 4300 ppb, and seems to correlate with melt S content. No systematic difference in gold soly. is obsd. between the adakitic and the non-?adakitic compns. investigated. Oxygen fugacity and the sulfur concn. in melt are the main parameters controlling the incorporation and concn. of gold in magmas. Certain adakitic and non-?adakitic magmas have high fO2 and magmatic S concns. favorable to the incorporation and transport of gold. Therefore, the cause of a particular assocn. between some arc magmas and Au-?Cu-?Mo deposits needs to be searched in the origin of those specialized magmas by involvement of Au- and S-?rich protoliths. The subducted slab, which contains metal-?rich massive sulfides, may constitute a potentially favorable protolith for the genesis of magmas specialized with respect to gold.

37.
Jiang L. et al. Rare earth element and yttrium (REY) geochemistry in carbonate reservoirs during deep burial diagenesis: Implications for REY mobility during thermochemical sulfate reduction // Chemical Geology. 2015. Vol. 415. P. 87–101.

The impact of burial diagenesis (esp. deep burial-?related processes such as thermochem. sulfate redn., TSR) on the distribution of rare earth elements and yttrium (REY) in diagenetic minerals in carbonate reservoir has gained little attention even though they may be unique indicators of the diagenetic system being closed or open to external influx of material. Trace element and REY concns., 87Sr?/86Sr, ?18O and ?13C have been detd. for limestone, host dolomite, pore-?filling calcite (calcite-?2)?, and late stage fracture-?filling calcite (calcite-?3)?, barite (barite-?2) and anhydrite (anhydrite-?3) from Lower Triassic Feixianguan Formation reservoirs in northeast Sichuan Basin, China. Calcite-?2, calcite-?3, barite-?2, and anhydrite-?3 pptd. during deep burial (from 110 °C to 220 °C)?, demonstrated by petrol. and fluid inclusion thermometry. Sr isotope anal. revealed that diagenetic carbonate minerals and anhydrite have largely identical 87Sr?/86Sr ratios to Triassic seawater, indicating negligible input of Sr from terrigenous sources and probably a relatively closed diagenetic environment for pptn. of these minerals. Carbon isotope anal. showed that calcite-?2 has relatively low ?13C values (down to - 18.9‰ V-?PDB)?, suggesting that they are TSR calcites with the carbonate derived from oxidized, isotopically-?light hydrocarbons. Unlike the seawater-?like REY patterns of the limestone and dolomites, calcite-?3 and anhydrite-?3 are enriched in rare earth elements (?REE) and show light rare earth element enrichment and heavy rare earth element depletion, exhibiting a chevron-?like pattern of shale normalized REY trends. In contrast, TSR calcite (calcite-?2) has similar ?REE to the host dolomite but a relatively flat REYSN pattern, suggesting strong variations in elemental and REE compns. of the burial fluids. Significantly, TSR calcite shows a prominent pos. Eu anomaly and an unusually high-?chondritic Y?/Ho ratio. Both yttrium vs. holmium fractionation and Eu2 + oxidn. to Eu3 + must have occurred during thermochem. sulfate redn. Hence, a pos. Eu anomaly and an elevated Y?/Ho ratio may be used as effective proxies to differentiate calcite resulting from TSR from ordinary calcite cement. This is esp. useful when carbon isotope anal. cannot be used to give an unambiguous interpretation of the origin of the calcite.

38.U18998
Jiang Y.-H. et al. Miocene potassic granite–syenite association in western Tibetan Plateau: Implications for shoshonitic and high Ba–Sr granite genesis // Lithos. 2012. Vol. 134-135. P. 146–162.

This paper presents detailed SHRIMP zircon U-?Pb chronol., mineral chem., major and trace element, and Sr-?Nd-?Hf isotope geochem. of two Cenozoic plutons (Karibasheng and Kuzigan) in western Tibetan Plateau, China. The Karibasheng pluton is composed of monzogranite, and the Kuzigan pluton consists of syenogranite, diopside-?bearing syenite and diopside syenite. SHRIMP zircon U-?Pb dating on monzogranite, syenogranite and diopside syenite shows that they were emplaced in Miocene (12-?10 Ma)?. These rocks are metaluminous and show the affinities with shoshonitic rocks, i.e., alkali-?rich (K2O + Na2O = 8.6-?13.4 wt.?%)?, high K2O contents (4.7-?10.6 wt.?%) with high K2O?/Na2O ratios (1.2-?4.6)?, enrichment in large ion lithophile elements (LILE) (e.g., Ba = 2200-?9100 ppm; Sr = 840-?3100 ppm, most > 1100 ppm) and rare earth elements (REE)?, esp. light REE (LREE) (La?/Yb up to 168)?. The rocks are depleted in high field strength elements (HFSE) but show high Nb?/Ta ratios (13.3-?30.7)?. The granites have lower initial 87Sr?/86Sr ratios (0.7091-?0.7099) and higher ?Nd (T) values (- 7.1 to - 9.5) than the syenites that have initial 87Sr?/86Sr ratios of 0.7095-?0.7117 and ?Nd (T) values of - 8.6 to - 12.2. Their zircon ?Hf (T) values (- 7.2 to - 9.7) are coupled with their whole-?rock ?Nd (T) values, and plot along the mantle array. The amphibole-?plagioclase thermometer and estn. of apatite satn. temp. indicate that the primary magmas had high temps. (up to 880 °C for the granites and up to 1100 °C for the syenites)?. The source depth for the granites and syenites is < 70-?100 km inferred by the metasomatic volatile phase (amphibole-?phlogopite) relation, and thus most probably within the upper part of lithospheric mantle. Detailed elemental and isotopic data and major element modeling suggest that the granites and syenites were derived directly by partial melting of the veined lithospheric mantle that had been hybridized by the continental slab-?derived melts. Continental slab break-?off was most likely the mechanism assocd. with the generation of these granites and syenites.

39.U12332
Jones A.M., Collins R.N., Waite T.D. Mineral species control of aluminum solubility in sulfate-rich acidic waters // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 4. P. 965–977.

The identification of the mineral species controlling the soly. of Al in acidic waters rich in sulfate has presented researchers with several challenges. One of the particular challenges is that the mineral species may be amorphous by X-?ray diffraction. The difficulty in discerning between adsorbed or structural sulfate is a further complication. Numerous studies have employed theor. calcns. to det. the Al mineral species forming in acid sulfate soil environments. The vast majority of these studies indicate the formation of a mineral species matching the stoichiometry of jurbanite, Al(OH)?SO4·5H2O. Much debate, however, exists as to the reality of jurbanite forming in natural environments, particularly in view of its apparent rare occurrence. In this work the use of Al, S and O K-?edge XANES spectroscopy, in combination with elemental compn. analyses of groundwater ppts. and a theor. anal. of sol. Al concns. ranging from pH 3.5 to 7, were employed to det. the mineral species controlling the soly. of Al draining from acid sulfate soils into Blacks Drain in northeastern New South Wales, Australia. The results indicate that a mixt. of amorphous Al hydroxide (Al(OH)?3) and basaluminite (Al4(SO4)?(OH)?10·5H2O) was forming. The use of XANES spectroscopy is particularly useful as it provides insight into the nature of the bond between sulfate and Al, and confirms the presence of basaluminite. This counters the possibility that an Al hydroxide species, with appreciable amts. of adsorbed sulfate, is forming within these groundwaters. Below approx. pH 4.5, prior to pptn. of this amorphous Al(OH)?3/basaluminite mixt., the studies indicate that the Al3+ activity of these acidic sulfate-?rich waters is limited by the availability of dissolved Al from exchangeable and amorphous?/poorly cryst. mineral species within adjacent soils. Further evidence suggests the Al3+ activity below pH 4.5 is then further controlled by diln. with either rainwater or pH 6-?8 buffered estuarine water, and not a notional Al(OH)?SO4 mineral species.

40.
Khatun S. et al. Platinum-group element (PGE) geochemistry of Mesoarchean ultramafic–mafic cumulate rocks and chromitites from the Nuasahi Massif, Singhbhum Craton (India) // Lithos. 2014. Vol. 205. P. 322–340.

The Mesoarchean Nuasahi Massif in eastern India comprises a lower ultramafic and an upper gabbro unit. The lower unit consists of orthopyroxenite, harzburgite, dunite and three chromitite bands. All of these rocks are characterized by adcumulate textures. The upper unit consists of gabbro with magnetite layers. At the contact between the eastern orthopyroxenite and the lower part of the upper gabbro, a sulfide-?rich breccia zone with platinum-?group-?element (PGE) mineralization is present. Detailed studies of major-?, trace- and PGE abundances suggest that the ultramafic-?mafic cumulate rocks, chromitites and breccias are genetically linked. The chondrite-?normalized U-?shaped rare earth element (REE) patterns of the harzburgite resemble those of Phanerozoic boninite. The overall U-?shaped REE patterns of the ultramafic rocks indicate derivation of the parental magma from a metasomatized depleted mantle source. The upper gabbros have higher relative abundances of trace elements than the lower ultramafic rocks, due to crystn. from a fractionated magma. Whole-?rock geochem. suggests that the lower ultramafic cumulate rocks with chromitites crystd. from a boninitic parental magma, whereas the upper gabbros with magnetite bands may be formed from residual boninitic magma that was contaminated by more tholeiitic-?like magmas. The boninitic parental magma that crystd. to form the lower ultramafic unit was most likely generated by second-?stage melting of a depleted metasomatized mantle source in a supra-?subduction zone (SSZ) setting and emplaced into crustal sequences. The PGE abundances in the Nuasahi rocks provide addnl. constraints on their geochem. evolution during the Mesoarchean. Primitive-?mantle-?normalized PGE diagrams show (1) Ru enrichment in chromitites (Pd?/Ru = 0.17-?0.64)?, (2) Pd?/Pt fractionation in both chromitites (Pd?/Pt = 3.1) and ultramafic rocks (Pd?/Pt = 0.62)?, (3) marked Ir depletion in ultramafic rocks (Pd?/Ir = 6.3) and (4) overall PGE enrichment in chromitites (PGEtotal = 142-?502 ppb)?. The large Ir depletion in the ultramafic rocks, and the overall Ir-?depleted character of other rocks from the Nuasahi Massif, may be related to multiple episodes of melt extn. from the mantle source, giving it a subchondritic character.

41.U12510
Kim J., Lee K.-Y., Kim J.-H. Metal-bearing molten sulfur collected from a submarine volcano: Implications for vapor transport of metals in seafloor hydrothermal systems // Geology. 2011. Vol. 39, № 4. P. 351–354.

Gray, metal-?bearing molten sulfur was collected from the central volcanic cone of an active off-?axis caldera (MTJ-?1) in the northeastern Lau Basin, southwestern Pacific Ocean, during an expedition for hydrothermal vents undertaken by the Korea Deep Ocean Study (KODOS) program in 2006. The molten sulfur enveloped the frame and chain bag of the dredge at a depth of ?1700 m. Microscopically, the sulfur matrix contains numerous covellite (CuS) inclusions of various sizes and irregular shapes, indicating their formation via volcanic sublimation. The molten sulfur is enriched in elements commonly assocd. with magmatic input, including Cu, As, Au, Bi, Te, and Sb. The low sulfur isotope compn. of the sulfur (?34S = -?7.5‰ to -?8.2‰) indicates an origin via the magmatic degassing of SO2 and disproportionation. The present results represent field-?scale evidence for metal transport via sulfur-?rich volcanic degassing in submarine massive sulfide deposits. The molten sulfur deposit plays an important role in enhancing the efficiency of the transfer of magmatic fluid to the hydrothermal system.

42.
Kong D.-X. et al. Electron microprobe analyses of ore minerals and H-O, S isotope geochemistry of the Yuerya gold deposit, eastern Hebei, China: Implications for ore genesis and mineralization // Ore Geology Reviews. 2015. Vol. 69. P. 199–216.

The Yuerya gold deposit in eastern Hebei Province, China, is located on the eastern margin of the North China Craton and is hosted by Mesozoic Yanshanian granitoid rocks and adjacent Mesoproterozoic Gaoyuzhuang Formation carbonates. The auriferous quartz veins in this deposit are dominated by pyrite, with subordinate sphalerite, chalcopyrite, and galena in a quartz-dominated gangue that also contains calcite, dolomite, barite, apatite, and fluorite. Gold is present as native gold and electrum, which are generally present as micron-size infillings in microfissures within pyrite and less commonly as tiny inclusions within pyrite, quartz, and tellurobismuthite. The pyrite in this deposit has high Co/Ni ratios and contains elevated concentrations of both of these elements, suggesting that the Yuerya gold deposit has a magmato-hydrothermal origin and that the ore-forming fluids that formed the deposit leached trace elements such as Co, Ni, As, and Au during passage through Archean metamorphic rocks. Mesoproterozoic carbonates, and the Yanshanian Yuerya granitoid. Pyrite in the study area has S/Se ratios and S isotopic compositions that suggest that the sulfur (and by inference the gold) within the deposit was sourced from magmato-hydrothermal fluids that were probably originally derived from Archean metamorphic rocks and Yanshanian granitoids. Tellurobismuthite in the study area is closely intergrown with gold and was the single telluride phase identified during this study. The fineness of gold associated with tellurobismuthite is greater than the fineness of gold associated with pyrite, although the fine particle size of the gold surrounded by tellurobismuthite means that the recovery of this gold is difficult in turn meaning that the tellurobismuthite has little significance to the economics of the Yuerya gold deposit. Only trace amounts of sulfides are associated with the tellurobismuthite within the Yuerya gold deposit, suggesting that this mineral was deposited under conditions of low fS(2) and/or high fTe(2). In addition, the presence of tellurides within the Yuerya gold deposit reflects a genetic relationship between the deposit and magmatism. Quartz from mineralized veins in the study area has 8180 values of 11.2 parts per thousand-12.9 parts per thousand and the fluids that formed these veins have delta D values of 78.3 parts per thousand to 72.1 parts per thousand. The delta S-34 values of pyrite within the deposit are rather restricted (2.3 parts per thousand-03.5 parts per thousand). These data, combined with the trace element geochemistry of sulfides within the deposit, suggest that the formation of the Yuerya gold deposit was closely related to both Archean metamorphic rocks and the Yanshanian Yuerya granitoid.

43.
Lach P. et al. In-situ Isotopic and Chemical Study of Pyrite from Chu-Sarysu (Kazakhstan) Roll-front Uranium Deposit // Procedia Earth and Planetary Science. 2015. Vol. 13. P. 207–210.

Pyrite is common in roll-front type uranium deposit in Chu-sarysu basin, Kazakhstan. Combined in-situ microstructural, isotopic and chemical analysis of pyrite indicates variation in precipitation conditions and in fluid composition. Broad-scale ?34S heterogeneity indicates a complex multi-facet evolution. First generation authigenic framboidal aggregates are biogenic as demonstrated by the lowest ?34S values of -48‰ to -28‰. The latest generation pyrites are probably hydrothermal with greater ?34S variation (-30‰ to +12‰). This hydrothermal pyrite commonly displays variable enrichment of several trace elements especially As, Co and Ni. Strong variation in ?34S values and variable trace element enrichment is interpreted in terms of continuous variations in fluid composition.

44.
Lai X. et al. New data of the Bayan Obo Fe–REE–Nb deposit, Inner Mongolia: Implications for ore genesis // Precambrian Research. 2015. Vol. 263. P. 108–122.

The Bayan Obo deposit in the Inner Mongolia, North China Craton, is the largest rare-earth element (REE) resource in the world. The deposit is hosted in Mesoproterozoic sediments of the Bayan Obo Group, the lithological sequence of which has been divided into seventeen units (H1–H17). The REE mineralization is mainly concentrated in the H8 dolomite unit, and therefore the depositional age of this unit is important in addressing the debate over the genesis of the REE–Fe–Nb ore deposit. Here we present U–Pb and Hf model ages of zircons from the adjacent H9 slate. Our data suggest that the H9 slate formed at 1505 ± 12 Ma and the H8 dolomite was deposited during the Mesoproterozoic. We also present Ar–Ar ages of riebeckite in veins cutting the H8 dolomite and biotite in the ore bodies which show 389.5 ± 3.0 Ma and 289.1 ± 1.8 Ma, respectively. The U–Pb measurements from overgrowth zircon in H9 slate give an age of 518.8 ± 7.5 Ma. These new age data indicate that the Bayan Obo deposit was disturbed during thermal events at 520 Ma to 390 Ma, generating a second phase of REE–Nb mineralization. The ?7Li values of the REE mineralized dolomite are similar to those of carbonatite dykes. Combined with ?Nd features, we provide geochemical evidences that REE mineralized dolomite has undergone fluid interaction. Results reveal that the carbonatite magmatism occurred within the Bayan Obo rift at ca. 1.2 Ga, provided the primary source for REE–Nb mineralization or to fertilize the Bayan Obo crust, and the later was remobilized during the Caledonian to generate the second phase of mineralization within a convergent plate margin regime.

45.
Lascelles D.F. Banded iron formation to high-grade iron ore: a critical review of supergene enrichment models // Australian Journal of Earth Sciences. 2012. Vol. 59, № 8. P. 1105–1125.

Review. All the major worldwide direct-shipping iron ore deposits associated with banded iron formations (BIF) are characteristically deeply weathered. They extend to considerable depths below the water table and show well-preserved primary structures and textures, but characteristically most deposits contain no evidence of chert bands being present prior to weathering. Recent studies have found evidence of hydrothermal and/ or metamorphic influences in the development of certain ore deposits and new genesis models such as the supergene-modified hypogene model have been postulated for major high-grade iron ore deposits. Nevertheless, there are many high-grade deposits that show no evidence of hypogene alteration and for which a hypogene or metamorphic genesis is unreasonable that are automatically ascribed to supergene enrichment, commonly erroneously attributed to lateritic weathering in tropical environments. Laterite (sensu lato) is a soil formation in which primary textures are destroyed and is underlain by a pallid zone showing the preservation of chert and the depletion, not enrichment, of iron oxides and thus is totally incompatible with the formation of the high-grade ore deposits. Various theories and models that purported to explain the conditions under which such a uniquely BIF-related dissolution of quartz and residual accumulation of hematite could occur by supergene processes typically conflict with current understanding of groundwater hydrology, chemistry, weathering processes and soil formation.Supergene enrichment of ore is universal in the leaching of gangue minerals such as iron silicates, carbonates and apatite and supergene enrichment of BIF to low-grade ore is common in near surface environments above the water table such as ferrugenised BIF outcrops, detrital ore deposits, and some shallow ore deposits that have been subjected to prolonged exposure to fresh meteoric water. In all cases of supergene enrichment traces of the chert bands are visible and the dissolution or replacement processes for the removal of quartz are clear, in direct contrast to the most important deep saprolite ore deposits that show no trace of chert bands.The widespread acceptance of an inappropriate and untenable supergene enrichment model inhibits search for the true origin of the ore and our ability to predict and find concealed high-grade ore deposits.

46.U12332
Laurila T.E. et al. Early depositional history of metalliferous sediments in the Atlantis II Deep of the Red Sea: Evidence from rare earth element geochemistry // Geochimica et Cosmochimica Acta. 2014. Vol. 126. P. 146–168.

The Atlantis II Deep is a brine-?filled depression on the slowly spreading Red Sea rift axis. It is by far the largest deposit of hydrothermally pptd. metals on the present ocean floor and the only known modern deposit that is analogous to laminated Fe-?rich chem. sediments, such as banded iron formation (BIF)?. The brine pool at the bottom of the Atlantis II Deep creates an environment where most of the hydrothermally sourced elements can be dispersed and deposited over an area of ?60 km2. We analyzed the rare earth element concns. in 100 small-?vol. samples from 9 cores in different parts of the Atlantis II Deep to better understand the origins of different types of metalliferous sediments (detrital, proximal hydrothermal and distal hydrothermal)?. Our results agree with earlier studies based on larger bulk samples that show the compn. of the major depositional units is related to major changes in the location and intensity of hydrothermal activity and the amt. of hydrothermal vs. background sedimentation. In this paper, we address the origins of chem. distinct laminae (down to sub-?millimeter) that correspond to ?annual deposition. REE patterns clearly reflect 3 different sources (e.g., detrital, scavenging, direct hydrothermal input)?. Detrital REE that are delivered to the Deep from outside account for most of the REE in the sediments of the Atlantis II Deep, similar to BIF, and are unaffected by fractionation due to hydrothermal processes during deposition and diagenesis. Fe- and Mn-?(oxy)?hydroxides that form at the anoxic-?oxic boundary scavenge REE from the brine pool as they settle. The Fe-?(oxy)?hydroxides contain a larger proportion of REE from seawater than any other sediment-?type and also scavenge REE from pore waters after deposition. In contrast, the Mn-?(oxy)?hydroxides dissolve before deposition and thus function as transporting agents between seawater and the brine. However, there is little evidence for direct seawater influence in the REE geochem. of the sediments (e.g., Y?/Ho ratio)?. Non-?ferrous sulfides form proximal to the hydrothermal vent source and inherit an hydrothermal REE pattern. The total REE content of the presently forming Fe-?(oxy)?hydroxides is very low due to limited input of REE into the brine. The largest proportion of non-?detrital REE appears to have been deposited early in the history of the basin from an initial brine pool that was relatively enriched in REE, followed by a change in REE chem. in later sediments. Similar abrupt changes in the REE chem. of ancient chem. sediments may record similar processes, including changes in local basin evolution and input of REE from different sources.

47.U12332
Lecumberri-Sanchez P., Steele-MacInnis M., Bodnar R.J. A numerical model to estimate trapping conditions of fluid inclusions that homogenize by halite disappearance // Geochimica et Cosmochimica Acta. 2012. Vol. 92. P. 14–22.

Fluid inclusions (FI) that homogenize by halite disappearance are common in some geological environments, and interpretation of microthermometric data from these inclusions has been limited by the lack of a model describing the PVTX relationships over the complete range of PTX conditions found in nature. In this study, a system of equations has been developed that can be used to estimate salinity, pressure and density of FI that homogenize by halite disappearance. The salinity, pressure, density and dP/dT slope of the FI isochore are calculated as functions of liquid–vapor homogenization temperature (Th) and halite dissolution temperature (Tm). The equations are based on a numerical model describing the isochoric pressure–temperature trajectory followed by halite-saturated fluids during heating. The model is valid for Th and Tm from 100 to 600 °C, and for pressures along the liquid–vapor–halite curve to 300 MPa.

48.U08182
Leybourne M.I., Goodfellow W.D. Geochemistry of surface waters associated with an undisturbed Zn–Pb massive sulfide deposit: Water–rock reactions, solute sources and the role of trace carbonate // Chemical Geology. 2010. Vol. 279, № 1-2. P. 40–54.

Results are reported of a detailed geochem. study of surface waters from several streams in a small catchment in northern New Brunswick, Canada. Rocks in the catchment represent metamorphosed (greenschist facies) felsic volcanic rocks, metavolcaniclastic sediments, and mafic volcanic rocks; no massive carbonate or evaporite lithologies are present, thus providing an excellent opportunity to investigate the relative influence of silicate weathering compared to trace carbonate (vein and disseminated) dissoln. and the influence of volcanogenic massive sulfide (VMS) mineralization on surface water chem. Surface waters, catchment lithologies and stream sediments were analyzed for a full suite of major and trace elements. Surface waters are dil. (typically <60 mg?/L total dissolved solids)?, and are of dominantly Ca-?HCO3-?type. Most waters have Ca?/Namolar >1. The major ion chem. of the waters is consistent with binary mixing between silicate weathering and dissoln. of trace calcite; Si?/Camolar relationships suggest that trace calcic silicates are insignificant compared to calcite as a Ca source, and PO4 concns. of waters are too low for apatite to be a major source of Ca. Host rocks have highly variable Ca?/Na, Mg?/Na and K?/Na values complicating the assignment of a silicate end-?member. Geochem. modeling indicates that surface waters range from essentially 100?% of the Na and Ca being derived by silicate weathering, to being dominantly controlled by trace calcite, also consistent with mass balance calcns. The Cl?/Ca ratios are consistent with the host felsic and mafic metavolcanic rocks as being an important source of Cl in addn. to pptn. The host lithologies have much larger variations in Mg?/Na, Ca?/Na, K?/Na, and Sr?/Na than the stream sediments and waters and the sediments are shifted to higher Mg?/Na and K?/Na and lower Ca?/Na than the waters. It is remarkable that the waters have such small variations in major ion ratios relative to the host rocks, indicating that the controls on solute loads of these streams is more a function of relative elemental soly. (Ca > Mg > Na)?, secondary mineral formation (e.g. Mg- and K-?rich clays)?, incongruent dissoln., and water-?rock reactions than end-?member rock compns. Oxidn. of massive and disseminated sulfide mineralization accounts for on av. 60?% of the dissolved sulfate. Calcns. indicate that sulfide oxidn. (sulfuric acid) weathering accounts for around 20?% of the cation flux in the watershed. On av. 12?% of the Ca and 72?% of the Mg are derived from silicate weathering, although cationic silicate denudation rates are only 1.88 tons?/km2/yr compared to 4.16 tons?/km2/yr for trace carbonate dissoln. The total cation denudation rate and CO2 consumption rate are similar to watersheds draining volcanic rocks in the Western Canadian Cordillera.

49.
Li G. et al. He-Ar Isotope Composition of Pyrite and Wolframite in the Tieshanlong Tungsten Deposit, Jiangxi, China: Implications for Fluid Evolution: He-Ar isotope of Tieshanlong W deposit // Resource Geology. 2011. Vol. 61, № 4. P. 356–366.

The Tieshanlong tungsten-?polymetallic deposit is a large wolframite deposit of quartz vein type located in southern Jiangxi, South China. It is genetically related to a high-?K S-?type granite. Seven pyrite and two wolframite samples, selected for He and Ar isotope analyses, yielded 3He?/4He values of 0.04-?0.98 Ra, 40Ar?/36Ar ratios of 293.5-?368.0, and 38Ar?/36Ar ratios of 0.176-?0.193. These data indicate that the ore-?forming fluids assocd. with the deposit did not result from a simple mixing of the crustal- and mantle-?derived end-?member fluids, but that primeval meteoric fluids were also involved in the generation of the assocd. granitic magma by partial melting of crustal metasedimentary rocks. Further investigations show that only minimal He from the mantle was added during generation of the assocd. granitic magma. It is postulated that boiling and second mixing with "new" meteoric fluids took place during migration of magmatic-?hydrothermal fluids into wall-?rock fractures, resulting in a drastic decrease of their metal transport capacity, which triggered the tungsten-?polymetallic mineralization.

50.
Liang Y. et al. A Study on the Mineralization of the Woxi Au-Sb-W Deposit, Western Hunan, China: Mineralization study of the Woxi deposit // Resource Geology. 2015. Vol. 65, № 1. P. 27–38.

The Woxi Au-?Sb-?W deposit in the western Hunan Province, China, is of hydrothermal vein type characterized by a rare mineral assemblage of stibnite, scheelite and native gold, of which gold fineness ranges from 998.6 to 1000. The mineralization sequence obsd. in the deposit is, from early to late, coarse-?grained pyrite - scheelite - stibnite - Pb-?Sb-?S minerals - sphalerite (+ cubanite) - fine-?grained pyrite. Native gold may have pptd. with scheelte. Microthermometric and LA-?ICP-?MS analyses of fluid inclusions in scheelite, quartz assocd. with scheelite and stibnite and barren quartz clarified that there may be at least three types of hydrothermal fluids during the vein formation in the Woxi deposit. Scheelite and native gold pptd. from the fluid of high temp. and salinity with high concns. of metal elements, followed by stibnite pptn. The later fluid of the highest temp. and salinity with low concns. of the elements yielded the sphalerite mineralization. The latest fluid of low temp. and salinity with low concns. of the elements is obsd. mainly in barren quartz. The remarkably high Au?/Ag concn. ratios detd. in the fluid inclusions in scheelite might be the reason for the extremely high gold fineness of native gold.

51.U49394
Liu K. et al. Trace element and REE geochemistry of Sanshenjiang gold deposit, southeastern Guizhou Province, China // Chinese Journal of Geochemistry. 2013. Vol. 32, № 2. P. 212–221.

The Sanshenjiang gold deposit in southeastern Guizhou Province, China, is hosted by the Neoproterozoic metasedimentary rocks which experienced low-?grade greenschist facies metamorphism. Gold mineralization occurs mainly in the ribbon chiltern slate of the first member of the Longli Formation and is controlled by both strata and faults. Ore bodies are characterized by abundant quartz-?arsenopyrite-?gold-?pyrite-?bedding veins, veinlets and small lenses within the shear zone. In this study, trace element and REE geochem. was analyzed to constrain the origin and genesis of this deposit. The trace element signatures of wall rocks and veins display a basically similar tendency in the spider diagram, showing the genetic relationship. The values of Co?/Ni, Y?/Ho, Hf?/Sm, Nb?/La and Th?/La reflect that the hydrothermal fluids of this deposit were derived from the mixt. of multiple sources with marked enrichment of Cl and moderate to high temp. There is a broad similarity in the chondrite-?normalized patterns and REE fractionation between wall rocks and ore bodies, possibly reflecting their similar origin. Based on the difference in ?Ce and ?Eu, quartz veins and lenses can be subdivided into weakly neg. Ce-?anomalies (?Ce=0.81 to 1.06) with slight Eu anomalies (?Eu=0.81 to 1.06) type and the significant pos. Ce-?anomalies (?Ce=1.13 to 1.97) with moderate neg. Eu-?anomalies type, probably suggesting phys.-?chem. changes in the evolution process of ore-?forming fluids from the early to late stage. It can be concluded that the ore-?forming process may have experienced three stages: formation of the original ore source bed, regional metamorphism and gold mineralization, on the basis of trace element and REE anal. and field observation.

52.
Liu Y. et al. Computational simulation of iron ore-forming processes in the Caiyuanzi siderite ore district, Guizhou, China // Journal of Geochemical Exploration. 2015. Vol. 158. P. 155–167.

By means of the FISH language in the FLAC code, the coupled pore-?fluid flow, heat transfer and mineralization have been simulated first with a generic model, and then with an actual geol. model in the Caiyuanzi siderite ore district, Guizhou. The effect of pore-?fluid pressure on the equil. concn. of siderite has been considered. The main purposes of this paper are: (1) to illustrate some simulation results for the possibility of hydrothermal mineralization of siderite in a sedimentary environment; (2) to get a better understanding of the processes and mechanism of siderite orebody formation in the sedimentary environment; (3) to analyze the influence of the concn. of carbon dioxide on the siderite mineralization; and (4) to compare the simulation results with the actual situation, so as to demonstrate that this simulation method is effective and feasible for understanding the mineralization mechanism of iron ore in the Caiyuanzi siderite ore district.

53.
Liu Y. et al. The Nature of Ore-forming Fluids of the Carlin-type Gold Deposit in Southwest China: A Case from the Zimudang Gold Deposit: Carlin-type gold deposit at Zumudang, SW China // Resource Geology. 2015. Vol. 65, № 2. P. 136–159.

The Zimudang gold deposit is a large Carlin-?type gold deposit in the Southwest Guizhou Province, China, with an av. Au content of 6.2 g?/t. Gold is mainly hosted in the fault zone and surrounding strata of the F1 fault and Permian Longtan Formation, and the ore bodies are strictly controlled by both the faults and strata. Detailed mineralogy and geochem. studies are conducted to help judge the nature of ore-?forming fluids. The results indicate that the Au is generally rich in the sulfides of both ores and wall rocks in the deposit, and the arsenian pyrite and arsenopyrite are the main gold-?bearing sulfides. Four subtypes of arsenian pyrite are found in the deposit, including the euhedral and subhedral pyrite, framboidal pyrite, pyrite aggregates and pyrite veins. The euhedral and subhedral pyrite, which can take up about 80?% of total pyrite grains, is the dominant type. Au distributed unevenly in the euhedral and subhedral pyrite, and the content of the Au in the rim is relatively higher than in the core. Au in the pyrite veins and pyrite aggregates is lower than the euhedral and subhedral pyrite. No Au has been detected in the points of framboidal pyrites in this study. An obvious highly enriched As rim exists in the X-?ray images of euhedral pyrites, implying the ore-?forming fluids may be rich in As. The relationship between Au and As reveals that the Au may host as a solid soln. (Au+) and nanoparticles of native gold (Au0) in the sulfides. The high Co?/Ni ratio (>1) of sulfides and the enrichment of W in the ores all reflect that the gold-?bearing minerals and ore-?forming process were mainly related to the hydrothermal fluids, but the magmatic and volcanic activities cannot be neglected. The general existence of Au and As in the sulfides of both ores and wall rocks and the REE results suggest that the ore-?forming fluids may mainly be derived from the basin itself. The enrichment of Tl suggests that the ore-?forming fluids may be enriched in Cl. The Ce and Eu show slightly or apparently neg. anomalies, which means the ore fluids were probably formed under reducing environment. The Y?/Ho ratios of ore samples fluctuate around 28, implying the bicarbonate complexation and fluorine were both involved in the ore-?forming process. Combined with the previous studies and our results, we infer that the ore-?forming fluids enriched Au, As, HS-? and halogen (F, Cl) were derived from the mixt. of reducing basinal fluids and magmatic or volcanic hydrothermal fluids.

54.U49394
Mao J. et al. Geochemical characteristics, cooling history and mineralization significance of Zhangtiantang pluton in South Jiangxi Province, P.R. China // Chinese Journal of Geochemistry. 2010. Vol. 29, № 1. P. 53–64.

The zircon SHRIMP dating of the Zhangtiantang granite gave an age of 159±7 Ma., which shows that the granite was emplaced at the early Late Jurassic. The Ar-?Ar plateau ages of biotite and K-?feldspar from the Zhangtiantang pluton are 153.2±1.1 Ma and 135.8±1.2 Ma, resp. The Ar-?Ar anti-?isochron ages of biotite and K-?feldspar are 152.5±1.7 Ma and 135.4±2.7 Ma, resp. The ages represent the isotopic closure ages of minerals in the pluton. The Zhangtiantang granites are peraluminous crust-?derived type granites with typical geochem. characteristics of calc-?alk. rocks of continental margin; these are enriched in Si, K, Al (av. value of A?/CNK as 1.18)?, HREE, Rb, U, and Th, heavily depleted in V, Cr, Co, Ni, Ti, Nb-?Ta, Zr, Sr, P, and Ba, with a strong neg. Eu anomaly and are corundum-?normative. The ?Nd(t) values of the Zhangtiantang granite are -?5.84 to -?7.79, and t2DM values are 1.69 to 1.83 Ga, which indicates partial melting of continental-?crust metamorphosed sedimentary rocks during the Middle Proterozoic. The cooling history of the Zhangtiantang granitic pluton indicates that the cooling rate of the pluton was faster (about 67°C?/Ma) from zircon (158 Ma) to biotite (152 Ma)?, and was slower (about 12°C?/Ma) from biotite (152.5 Ma) to K-?feldspar (135.8 Ma)?. The temporal gap (about 10 Ma) between the granite formation and W-?Sn ore mineralization in South China may be related to ordinary magmatic-?hydrothermal processes based on the variations in cooling curve of the pluton. The Zhangtiantang pluton was formed in a compression setting, with differentiation-?aided evolution and mineralization occurring in a relative relaxation setting.

55.
Nansai K. et al. Global mining risk footprint of critical metals necessary for low-carbon technologies: The case of neodymium, cobalt, and platinum in Japan // Environmental Science and Technology. 2015. Vol. 49, № 4. P. 2022–2031.

Meeting the 2-degree global warming target requires wide adoption of low-carbon energy technologies. Many such technologies rely on the use of precious metals, however, increasing the dependence of national economies on these resources. Among such metals, those with supply security concerns are referred to as critical metals. Using the Policy Potential Index developed by the Fraser Institute, this study developed a new footprint indicator, the mining risk footprint (MRF), to quantify the mining risk directly and indirectly affecting a national economy through its consumption of critical metals. We formulated the MRF as a product of the material footprint (MF) of the consuming country and the mining risks of the countries where the materials are mined. A case study was conducted for the 2005 Japanese economy to determine the MF and MRF for three critical metals essential for emerging energy technologies: neodymium, cobalt and platinum. The results indicate that in 2005 the MFs generated by Japanese domestic final demand, that is, the consumption-based metal output of Japan, were 1.0 ? 103 t for neodymium, 9.4 ? 103 t for cobalt, and 2.1 ? 10 t for platinum. Export demand contributes most to the MF, accounting for 3.0 ? 103 t, 1.3 ? 105 t, and 3.1 ? 10 t, respectively. The MRFs of Japanese total final demand (domestic plus export) were calculated to be 1.7 ? 10 points for neodymium, 4.5 ? 10-2 points for cobalt, and 5.6 points for platinum, implying that the Japanese economy is incurring a high mining risk through its use of neodymium. This country's MRFs are all dominated by export demand. The paper concludes by discussing the policy implications and future research directions for measuring the MFs and MRFs of critical metals. For countries poorly endowed with mineral resources, adopting low-carbon energy technologies may imply a shifting of risk from carbon resources to other natural resources, in particular critical metals, and a trade-off between increased mining risk and deployment of such technologies. Our analysis constitutes a first step toward quantifying and managing the risks associated with natural resource mining.

56.
Nassar N.T. et al. Criticality of the Geological Copper Family // Environmental Science & Technology. 2012. Vol. 46, № 2. P. 1071–1078.

Because modern technology depends on reliable supplies of a wide variety of materials, and because of increasing concern about those supplies, a comprehensive methodology has been created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to the elements of the geological copper family: Cu, As, Se, Ag, Te, and Au. These elements are technologically important, but show a substantial variation in different factors relating to their supply risk, vulnerability to supply restriction, and environmental implications. Assessments are made on corporate, national, and global levels for year 2008. Evaluations of each of the multiple indicators are presented and the results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates for each of the aggregated evaluations. For supply risk over both the medium term and long term, As is the highest risk of the six metals, with Se and Ag nearly as high. Gold has the most severe environmental implications ranking. Vulnerability to supply restriction (VSR) at the corporate level for an invented solar cell manufacturing firm shows Se, Te, and Cu as approximately equal, Cu has the highest VSR at the national level, and Cu and Au have the highest VSRs at the global level. Criticality vector magnitudes are greatest at the global level for As (and then Au and Ag) and at the national level for As and Au; at the corporate level, Se is highest with Te and Cu lower. An extension of this work, now in progress, will provide criticality estimates for several different development scenarios for the period 2010-2050.

57.U12332
Nozaki T., Kato Y., Suzuki K. Re–Os geochronology of the Iimori Besshi-type massive sulfide deposit in the Sanbagawa metamorphic belt, Japan // Geochimica et Cosmochimica Acta. 2010. Vol. 74, № 15. P. 4322–4331.

Although there are numerous Besshi-?type deposits in the Sanbagawa metamorphic belt, Japan, their tectonic settings and depositional environments remain controversial because of a lack of depositional age constraints. The authors report Re-?Os data for the Iimori deposit, one of the largest Besshi-?type deposits in western Kii Peninsula, to examine the robustness of the Re-?Os isotope system for dating sulfide minerals in the high-?pressure,?high temp. metamorphic belt and to elucidate the primary depositional environment of the Iimori sulfide ores. An 11-?point Re-?Os isochron plot yields an age of 156.8 ± 3.6 Myr. As this Re-?Os isochron age is significantly older than the timing of the Sanbagawa peak metamorphism (110-?120 or ?90 Myr) and a well-?defined isochron was obtained, the Re-?Os age detd. is most likely the primary depositional age. Despite high-?grade metamorphism at up to 520 ± 25 °C and 8-?9.5 kbar, the Re-?Os isotope system of the Iimori sulfides was not disturbed. Hence, the whole-?rock Re-?Os closure temp. for the Iimori sulfide ores was probably > 500 °C. As the accretion age of the Sanbagawa metamorphic belt is considered to be 120-?130 or 65-?90 Myr on the basis of radiolarian and radiometric ages, the authors estd. the time from the Iimori sulfide deposition on the paleo-?seafloor to its accretion at the convergent plate boundary to be > 25 Myr. Consequently, the depositional environment of the Iimori sulfide ores was not in the marginal sea, but was truly pelagic.

58.
Nuss P. et al. Criticality of Iron and Its Principal Alloying Elements // Environmental Science & Technology. 2014. Vol. 48, № 7. P. 4171–4177.

Because modern technology depends on reliable supplies of a wide variety of materials and because of increasing concern about those supplies, a comprehensive methodology was created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to iron and several of its main alloying elements (i.e., vanadium, chromium, manganese, and niobium). These elements represent the basic metals of any industrial society and are vital for national security and economic well-being. Assessments relating to the dimensions of criticality - supply risk, vulnerability to supply restriction, and environmental implications - for 2008 are made on the global level and for the United States. Evaluations of each of the multiple indicators are presented, with aggregate results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates. Iron has the lowest supply risk, primarily because of its widespread geological occurrence. Vanadium displays the highest cradle-to-gate environmental implications, followed by niobium, chromium, manganese, and iron. Chromium and manganese, both essential in steel making, display the highest vulnerability to supply restriction, largely because substitution or substitution at equal performance is not possible for all end-uses. From a comprehensive perspective, we regard the overall criticality as low for iron and modest for the alloying elements we evaluated.

59.
Pan X., Liu W., Hou Z. Ore-Forming Fluids as Sampled by Sulfide- and Quartz-Hosted Fluid Inclusions in the Jinwozi Lode Gold Deposit, Eastern Tianshan Mountains of China: Ore-forming fluid in Jinwozi gold deposit // Resource Geology. 2014. Vol. 64, № 3. P. 183–208.

The Jinwozi lode gold deposit in the eastern Tianshan Mountains of China includes auriferous quartz veins and network quartz veins that are exemplified by the Veins 3 and 210, resp. This paper presents H-?, O-?isotope compns. and gas compns. of fluid inclusions hosted in sulfides and quartz, and S-?, Pb-?isotope compns. of sulfide separates collected from the principal Stage 2 ores in Veins 3 and 210. Fluid inclusions trapped in quartz and sphalerite are pseudo-?secondary and primary. They were trapped from the fluids during the successive or alternate pptn. of quartz with sulfides. H- and O-?isotope compns. of fluid inclusion of three pyrite and one quartz separates from Vein 210 plot within the field of degassed melt, which is evidence for the incorporation of magmatic fluid as well with some possibility of contribution of metamorphic water to the hydrothermal system since the two datasets show a higher oxygen isotopic ratio than those of degassed melt. However, ?D and ?18O values of fluid inclusions hosted in sulfides and quartz from Vein 3 are distinctly lower than those from Vein 210. In addn., salinities of fluid inclusion from Vein 3, approx. 3 to 6 wt?% NaCl equiv., are considerably lower than those from Vein 210, which are approx. 8 to 14 wt?% NaCl equiv. Ore-?forming fluids of Veins 3 and 210 have migrated through the relatively high and low levels in the imbricate-?thrust column where rock deformation is characterized by dilatancy or ductile-?brittle transition, resp. Therefore, the ore-?forming fluid of Vein 3 is interpreted to have mixed with greater amts. of meteoric-?derived groundwater than that of Vein 210. Fluid inclusions hosted in sulfides contain considerably higher abundances of gaseous species of CO2, N2, H2S, and so on, than those hosted in quartz. Many of these gaseous species exhibit linear correlations with H2O. These linear trends are interpreted in terms of mixing between magmatic fluid and groundwater. The relative enrichment of gaseous species in fluid inclusions hosted in sulfides, coupled with the banded ore structure, suggests that the magmatic fluid was involved with the ore-?forming fluid in pulsation. Lead isotope compns. of 21 pyrite and galena separates form a linear trend, suggesting mixing of metallic materials from diverse reservoirs. The ?34S values of pyrite and galena range from +5.6‰ to +7.9‰ and from +3.1‰ to +6.3‰, resp., indicating sulfur of the Jinwozi deposit has been leached mainly from the granodiorite and partly from the Jinwozi Formation by the circulating ore-?forming fluid.

60.U12510
Pandur K., Ansdell K.M., Kontak D.J. Graphic-textured inclusions in apatite: Evidence for pegmatitic growth in a REE-enriched carbonatitic system // Geology. 2015. Vol. 43, № 6. P. 547–550.u1

Graphic texture, most common in felsic pegmatites, is documented here in an unusual setting, within apatite of the Hoidas Lake light rare earth element (LREE) deposit, an inferred distal pegmatitic-?hydrothermal counterpart of a carbonatite in northern Saskatchewan, Canada. The graphic texture is displayed by vermicular and cuneiform LREE-?rich inclusions which define primary growth zones in apatite. Integrated electron microprobe anal. and scanning electron microscope-?energy dispersive X-?ray spectroscopy imaging document the unusual and heterogeneous compns. of the inclusions, which vary between Ce2O3 + SiO2 (+ ThO2)?-?dominant and La2O3 + Nd2O3 (+ F)?-?dominant end members. Here we discuss the formation of these graphic-?textured inclusions in the context of models suggested for the formation of graphic quartz-?K-?feldspar intergrowths in granitic pegmatites, based on the similarity of these features.

61.
Panigrahi M.K. et al. Reconstruction of Physicochemical Environment of Hydrothermal Mineralization at Malanjkhand Copper Deposit, Central India: Constraints from Sulfur Isotope Ratios in Pyrite, Molybdenite and Chalcopyrite: Malanjkhand Copper Deposit // Resource Geology. 2013. Vol. 63, № 1. P. 110–116.

?34S values of pyrite, molybdenite and chalcopyrite were detd. from the Malanjkhand copper deposit. These minerals constitute the primary sulfide phases that were deposited after the initial magnetite deposition in the main orebody and host granitoid. Pyrite exhibits a depleted range of values (-?2.63 to -?0.56‰)?, chalcopyrite, a very narrow range of values around zero (-?0.039 to 0.201‰) and molybdenite furnishes a range of enriched values (0.68 to 1.98‰)?. On back calcn. of the ?34S values of H2S in the fluid from which the minerals were likely to have pptd., using std. expressions for equil. fractionation at the temp. range obtained from fluid inclusion and mineral fluid equil., it is obsd. that H2S in the fluid at pyrite deposition was depleted and gradually became enriched towards molybdenite and chalcopyrite deposition. This trend is best explained as being due to inorg. redn. of SO42-? in the fluid and is very much in agreement with the paragenetic sequence indicating increasing activity of H2S in the fluid. The very restricted range in the ?34S values of sulfide minerals in the fluid does indicate a single, possibly magmatic, source of sulfur that also agrees well with the earlier deduced model of genesis of the deposit as an ancient geothermal system assocd. with granitic magmatism.

62.
Pavlova G.G., Borovikov A.A. Silver–antimony deposits of Central Asia: physico-chemical model of formation and sources of mineralisation // Australian Journal of Earth Sciences. 2010. Vol. 57, № 6. P. 755–775.

Questions on the origin of Ag–Sb deposits are considered for several large economic ore districts in Central Asia: southeast Pamir (Tajikistan), Talas in northern Tien Shan (Kyrgyzstan), southeast Altai and northwest Mongolia, and Verkhoyansk province (Yakutia). The Ag–Sb mineralisation of Central Asia is spatially and temporally associated with alkaline mafic magmatism, and occasionally with coeval granitoid magmatism. Ag–Sb deposits have close spatial and temporal relationships with granitoid and alkaline mafic magmatism. The Ag–Sb deposits were formed in the temperature range 50–280°C, from Ag-specific reduced two-phase hydrothermal fluids containing a highly concentrated chloride solution (NaCl > FeCl2 > CaCl2 > KCl > MnCl2) and a high-density CO2+ CH4 ± N2 gaseous phase. Fluid salinities range widely from 40 to 0.1 wt% NaCl equiv. Geochemical specialisation of Ag–Sb ore is caused by chemical features of chloride brines enriched in Ag, Sb, Pb and Cu, with a relatively low Au content (?10?6 mol/kg) within a pH of 3.5–4. The highest temperatures, concentrations of solutions and ore elements in the ore fluids were found in early quartz of siderite–tetrahedrite veins from below-ore level of the ore-forming system. Vertical zonation of the Ag–Sb mineralisation is caused by precipitation of different mineral associations from the same solution with temperatures decreasing towards the upper parts of the system. Sufficient vertical range of mineralisation (600–800 m) and relatively low Ag contents in the ore (300–600 ppm) result from the temperature decrease and absence of geochemical barriers. Higher temperature gradient and dilution of magmatogenic fluid with meteoric water was a geochemical barrier for the Ag-rich ore formation in a narrow (about 400 m) main ore deposition zone. Lateral zonation of Ag–Sb mineralisation is related to a staged development of the ore-forming process and deposition of different stage mineral associations at the beginning and end of the hydrothermal process. The Ag–Sb deposits are polygenic in terms of sources of ore elements and ore-forming fluids. Ore elements may have been inherited from magmatic and terrigenous host-rocks of different ages. Temporal correlation of the Ag–Sb mineralisation with alkaline mafic magmatism, He isotope composition and Hg contents in the ores confirm participation of a mantle source in the formation of the Ag–Sb deposits.

63.U08182
Perez-Lopez R. et al. Rare earth element geochemistry of sulphide weathering in the Sao Domingos mine area (Iberian Pyrite Belt): A proxy for fluid–rock interaction and ancient mining pollution // Chemical Geology. 2010. Vol. 276, № 1-2. P. 29–40.

Gossan, disseminated orebody waste, other mining wastes, minesoils and acid mine drainage (AMD) in the abandoned Sao Domingos mine area (Iberian Pyrite Belt, IPB) have been analyzed for rare earth elements (REE)?. The main aim is to understand REE mobility during sulfide weathering so that the lanthanide series can be used both as a record of the water-?rock interaction and as a tool for identifying impacts of AMD on natural ecosystems. North-?American Shale Composite (NASC)?-?normalized REE patterns corresponding to the disseminated orebody waste are relatively flat (E MREE = - 0.01 ± 0.12)?. However, NASC-?normalized REE distributions in AMD from sulfide oxidn. tend to be enriched in middle-?REE (MREE) compared to light-?REE (LREE) and heavy-?REE (HREE)?. As a consequence, gossan resulting from supergene alteration of massive sulfide presents an evident NASC-?normalized MREE-?depleted signature. Thus, the overall water-?sulfide interaction defines complementary convex (E MREE = + 0.72 ± 0.25) and concave (E MREE = - 0.31 ± 0.12) NASC-?normalized patterns in draining waters and oxidn. products, resp. Solns. extd. from minesoils have also NASC-?normalized patterns with MREE-?enriched signature (E MREE = + 0.62 ± 0.22) similar to AMD. The E MREE parameter is proposed to measure the curvature in the MREE segment, and its size is quantified as the normalized max. vertical difference between the polynomial curve fitting of the MREE region and its theor. Y-?axis position in the absence of enrichment or depletion (E MREE > 0 for MREE-?enriched signatures; < 0 for MREE-?depleted signatures; and = 0 for horizontal patterns)?. The Sao Domingos stream, although it has been highly affected by AMD, flows into the Guadiana river that has an estuarine system where pollution is considerably attenuated due to the mixing, according to the metal geoaccumulation indexes currently used in the literature. However, sediments of this estuary were also analyzed and reflect MREE-?enriched signatures (EMREE = + 0.25 ± 0.03)?, which demonstrate that this apparently non-?polluted estuarine system is being certainly affected by historical mining activities from the IPB. The E MREE index is more sensitive to recognize curved MREE-?signatures than other normalized ratios such as (La?/Gd)?NASC, validating the use of REE patterns as a proxy for environmental pollution by AMD.

64.
Posth N.R. et al. Simulating Precambrian banded iron formation diagenesis // Chemical Geology. 2013. Vol. 362. P. 66–73.

Post-?depositional diagenetic alteration makes the accurate interpretation of key pptn. processes in ancient sediments, such as Precambrian banded iron formations (BIFs)?, difficult. While microorganisms are proposed as key contributors to BIF deposition, the diagenetic transformation of precursor Fe(III) minerals assocd. with microbial biomass had not been exptl. tested. The authors incubated mixts. of ferrihydrite (proxy for biogenic ferric oxyhydroxide minerals) and glucose (proxy for microbial biomass) in gold capsules at 1.2 kbar and 170 °C. Both wet chem. anal. and mineralogical methods (microscopy, X-?ray diffraction and Mossbauer spectroscopy) were used to analyze the reaction products. Under these conditions, ferrihydrite (FeIII(OH)?3) transforms to hematite (Fe2IIIO3)?, magnetite (FeIIFe2IIIO4)?, and siderite (FeIICO3)?. Silica-?coated ferrihydrite prepd. at conservative Si:Fe ratios (as predicted for the Precambrian oceans) and mixed with glucose yielded hematite and siderite, whereas magnetite could not be identified microscopically. Our results show that electron transfer from org. carbon to Fe(III) minerals during temp.?/pressure diagenesis can drive the prodn. of key BIF minerals. Our results also demonstrate that the post-?depositional mineralogy of BIF does not directly archive the oceanic or atm. conditions present on Earth during their lithification. As a consequence, atm. compn. regarding concns. of methane and CO2 during the time of BIF mineral deposition cannot be directly inferred from BIF mineralogical data alone.

65.U12332
Reich M. et al. Pyrite as a record of hydrothermal fluid evolution in a porphyry copper system: A SIMS/EMPA trace element study // Geochimica et Cosmochimica Acta. 2013. Vol. 104. P. 42–62.

Porphyry copper deposits are currently the world's largest source of copper and molybdenum, and are also among the largest reservoirs of gold in the upper crust. Despite the fact that pyrite is a ubiquitous mineral phase in these deposits and secondary Cu enrichment processes are commonly controlled by the abundance of this sulfide, the major and trace element chem. of pyrite from porphyry systems remains unconstrained. The authors report the first comprehensive trace element database of pyrite from the Dexing deposit, China's largest porphyry Cu deposit. By combining high-?spatial resoln. and X-?ray mapping capabilities of electron microprobe anal. (EMPA) with low detection limits and depth-?profiling capabilities of secondary-?ion mass spectrometry (SIMS) in a suite of samples from the Dexing deposit, the authors show that the concns. of precious metals (e.g., Au, Ag)?, metalloids (e.g., As, Sb, Se, Te) and heavy metals (e.g., Cu, Co, Ni, Zn, Hg) in pyrite from porphyry systems are more significant than previously thought. Among the elements analyzed, Cu, As, Au and Ni are the most abundant with concns. that vary from sub-?ppm levels to a few wt.?% (i.e., ?6 wt.?% Cu, ?3 wt.?% As, ?0.25 wt.?% Au, and ?0.2 wt.?% Ni)?. Detailed wavelength-?dispersive spectrometry (WDS) X-?ray maps and SIMS depth vs. isotope concn. profiles reveal that pyrite from the Dexing deposit is characterized by complex chem. zoning where the studied elements occur in different mineralogical forms. While As occurs as a structurally bound element in pyrite, Cu and Au can occur as both solid soln. and micro- to nano-?sized particles of chalcopyrite and native Au (or Au tellurides)?, resp., indicating that pyrite can control metal speciation and partitioning during porphyry Cu mineralization. The well-?developed oscillatory zoning detected in pyrite, where Cu-?rich, As-?depleted growth zones alternate with Cu-?depleted, As-?rich layers, indicates that Cu is geochem. decoupled from As, suggesting that this selective partitioning of metals into pyrite is most likely the result of changes in hydrothermal fluid compn.

66.U08182
Reichow M.K. et al. Multi-stage emplacement of alkaline and peralkaline syenite–granite suites in the Mongolian–Transbaikalian Belt, Russia: Evidence from U–Pb geochronology and whole rock geochemistry // Chemical Geology. 2010. Vol. 273, № 1-2. P. 120–135.

The Mongolian-?Transbaikalian Belt (MTB) is the largest and most representative component of the Central-?Asian network of Late Paleozoic and Mesozoic granites and syenites and assocd. volcanic rocks. The MTB incorporates over 350 individual plutons and numerous volcanic fields, predominantly of alk. and peralkaline compn. New U-?Pb zircon and titanite geochronol. data are given for 5 plutonic complexes located in the central part of the MTB. Four of them (Bryansky, Khorinsk, Kharitonovo and Malo-?Kunalei) are peralkaline and alkali-?feldspar granitoids, and one plutonic complex (Ust-?Khilok) represents a shoshonitic series (K-?rich gabbro, monzonite and syenite)?. The new data confirm the presence of three distinct stages of highly alk. magmatic activity within the MTB: Early Permian (280-?275 Myr)?, Late Triassic (230-?219 Myr) and Late Jurassic (? 152 Myr)?. The dated shoshonitic plutonic complex formed between 280 and 278 Myr, overlapping with the formation of the Early Permian alkali-?feldspar-?peralkaline granitoid rocks. The ages of the alkali-?feldspar and peralkaline magmatic suites are indistinguishable within a single magmatic complex. This suggests that several episodes of syenite and granite magma emplacement occurred within < 2 Myr intervals. The close assocn. in space and time of geochem. distinct igneous rocks points to co-?existence of discrete magma chambers comprising magma from different sources. Early Permian magmatic activity in the MTB completed a continuous post-?collisional cycle of magmatism that started in the Carboniferous (at ? 330 Myr) and lasted for about 50 Myr. The Late Triassic stage marks the beginning of anorogenic tectonic setting in the MTB evolution. Late Jurassic peralkaline magmatism in the territory of the MTB is related to the formation of Mesozoic metamorphic core complexes, which are abundant in northern Mongolia and Transbaikalia and formed in an anorogenic within-?plate environment.

67.U12332
Richard A. et al. An evaporated seawater origin for the ore-forming brines in unconformity-related uranium deposits (Athabasca Basin, Canada): Cl/Br and ?37Cl analysis of fluid inclusions // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 10. P. 2792–2810.

Analyses of halogen concn. and stable chlorine isotope compn. of fluid inclusions from hydrothermal quartz and carbonate veins spatially and temporally assocd. with giant unconformity-?related uranium deposits from the Paleoproterozoic Athabasca Basin (Canada) were performed to det. the origin of chloride in the ore-?forming brines. Microthermometric analyses show that samples contain variable amts. of a NaCl-?rich brine (Cl concn. between 120,?000 and 180,?000 ppm) and a CaCl2-?rich brine (Cl concn. between 160,?000 and 220,?000 ppm)?. Molar Cl?/Br ratios of fluid inclusion leachates range from ?100 to ?900, with most values between 150 and 350. Cl?/Br ratios below 650 (seawater value) indicate that the high salinities were acquired by evapn. of seawater. Most ?37Cl values are between -?0.6‰ and 0‰ (seawater value) which is also compatible with a common evapd. seawater origin for both NaCl- and CaCl2-?rich brines. Slight discrepancies between the Cl concn., Cl?/Br, ?37Cl data and seawater evapn. trends, indicate that the evapd. seawater underwent secondary minor modification of its compn. by: (i) mixing with a minor amt. of halite-?dissoln. brine or re-?equilibration with halite during burial; (ii) diln. in a max. of 30?% of connate and?/or formation waters during its migration towards the base of the Athabasca sandstones; (iii) leaching of chloride from biotites within basement rocks and (iv) water loss by hydration reactions in alteration haloes linked to uranium deposition. The chloride in uranium ore-?forming brines of the Athabasca Basin has an unambiguous dominantly marine origin and has required large-?scale seawater evapn. and evaporite deposition. Although the direct evidence for evaporative environments in the Athabasca Basin are lacking due to the erosion of ?80?% of the sedimentary pile, Cl?/Br ratios and ?37Cl values of brines have behaved conservatively at the basin scale and throughout basin history.

68.
Richard A. et al. Synchrotron XRF and XANES investigation of uranium speciation and element distribution in fluid inclusions from unconformity-related uranium deposits // Geofluids. 2013. Vol. 13, № 2. P. 101–111.

Fluid inclusions from two quartz samples of the McArthur River and Rabbit Lake unconformity-?related uranium deposits (Athabasca Basin, Canada) were analyzed by synchrotron X-?ray fluorescence (SXRF) and X-?ray absorption near-?edge spectroscopy (XANES) to shed light on (i) the detailed chem. of the fluids having transported the uranium and (ii) the speciation of uranium in these fluids. The analyzed samples contain variable proportions of NaCl-?rich or CaCl2-?rich (25-?35 wt?% salts) fluid inclusions that homogenise into the liq. phase between 120 and 200°C. For unknown reason, all of the CaCl2-?rich fluid inclusions decrepitate under X-?ray beam after a few seconds, precluding any SXRF or XANES measurement. SXRF on 12 homogenised NaCl-?rich fluid inclusions from the Rabbit Lake sample shows that the fluid inclusions contain appreciable amts. of Br, Fe, Sr, transition metals (Mn, Ni, Cu, Zn)?, Pb, U and rare earth elements (REE) (La, Ce)?, with concns. being relatively homogeneous among fluid inclusions. Within the complex McArthur River sample (numerous fluid inclusions + randomly distributed solids)?, statistical analyses of hyperspectral SXRF images were performed using the non-?neg. matrix approxn. (NNMA) method. This strategy allows distinguishing the three domains contributing to the overall signal: (i) the quartz matrix, which notably contains significant amts. of Cr, Cu and Pb; (ii) the fluid inclusions characterised by high amts. of Br, Fe, Sr and transition metals; and (iii) La-?Ce ± Fe solids. Part of the U and REE are spatially assocd. with distinct optically invisible solids within the quartz matrix. XANES on four McArthur River sample fluid inclusions at room temp. and at 150°C (fluid inclusion trapping temp.) as well as in solid and liq. U(IV) and U(VI) stds., resp., shows that the uranium has remained in the form of U(VI) from trapping to present in the fluid inclusion.

69.
Richards J.P. The oxidation state, and sulfur and Cu contents of arc magmas: implications for metallogeny // Lithos. 2015. Vol. 233. P. 27–45.

Global data for measured Fe2O3/FeO ratios and Cu contents in unaltered volcanic and intrusive arc rocks indicate that, on av., they are slightly more oxidized than other magmas derived from depleted upper mantle (such as MORB)?, but contain similar Cu contents across their compositional ranges. Although Cu scatters to elevated values in some intermediate compn. samples, the bulk of the data show a steady but gentle trend to lower concns. with differentiation, reaching modal values of ? 50-?100 ppm in andesitic rocks. These data suggest that Cu is mildly compatible during partial melting and fractionation processes, likely reflecting minor degrees of sulfide satn. throughout the magmatic cycle. However, the vol. of sulfides must be small such that significant proportions of the metal content remain in the magma during fractionation to intermediate compns. Previous studies have shown that andesitic magmas contg. ? 50 ppm Cu can readily form large porphyry-?type Cu deposits upon emplacement in the upper crust.A review of the literature suggests that the elevated oxidn. state in the asthenospheric mantle wedge source of arc magmas (?FMQ ? + 1 ± 1) derives from the subduction of seawater-?altered and oxidized oceanic crust, and is transmitted into the mantle wedge via prograde metamorphic dehydration fluids carrying sulfate and other oxidizing components. Progressive hydration and oxidn. of the mantle wedge may take up to ? 10 m.y. to reach a steady state from the onset of subduction, explaining the rarity of porphyry deposits in primitive island arcs, and the late formation of porphyries in continental arc magmatic cycles. Magmas generated from this metasomatized and moderately oxidized mantle source will be hydrous basalts contg. high concns. of sulfur, mainly dissolved as sulfate or sulfite. Some condensed sulfides (melt or minerals) may be present due to the high overall fS2, despite the moderately high oxidn. state. These sulfides may retain some highly siderophile elements in the source, but are unlikely to be sufficiently voluminous to significantly affect the budget of more modestly sulfide-?compatible and more abundant elements such as Cu and Mo. These primary magmas can therefore be considered to be largely Cu-?Mo-?undepleted, although highly siderophile elements such as Au and platinum group elements (PGE) may be depleted unless no sulfides remain in the source. The latter condition seems unlikely during active subduction because of the continuous flux of fresh sulfur from the slab, but may occur during post-?subduction re-?melting (leading to potentially Au-?rich post-?subduction porphyry and alkalic-?type epithermal systems)?.Lower crustal differentiation of main-?stage arc magmas results in some loss of Cu to residual or cumulate sulfides, but again the amt. appears to be minor, and does not drastically reduce the Cu content of deriv. intermediate-?compn. melts. Fractionation and devolatilization affect the oxidn. state of the magma in competing ways, but, while crystn. and segregation of Fe3 +-?rich magnetite can cause redn. in reduced to moderately oxidized evolved magmas, this effect appears to be outweighed by the oxidative effects of degassing reduced or weakly oxidized gaseous species such as H2, H2S, and SIVO2, and preferential solvation and removal of Fe2 + in saline hydrothermal fluids. Consequently, most arc magmatic suites show slight increases in oxidn. state during differentiation, reaching typical values of ?FMQ = + 1 to + 2.This oxidn. state is significant, because it corresponds to the transition from dissolved sulfide to sulfate dominance in magmas. It has been shown that Cu and Au solubilities in silicate magma increase up to this level (?FMQ ? + 1)?, but while Cu soly. continues to increase at higher oxidn. states, Au shows a precipitous drop as sulfide, which solvates Au in the melt, is converted to sulfate. This may explain the somewhat restricted distribution of Au-?rich porphyry Cu

70.
Seredin V.V. et al. Coal deposits as promising sources of rare metals for alternative power and energy-efficient technologies // Applied Geochemistry. 2013. Vol. 31. P. 1–11.

A review. This paper presents data on widespread abnormal accumulations in coal deposits of some rare metal(loid)?s (Ge, Ga, Se, Li and REE + Y)?, which play a key role in energy-?efficient technologies and alternative power development. It is shown that enrichment of these metal(loid)?s may occur in coal seams in host- and basement-?rocks of coal basins at comparable concns. to those in conventional ores. Genesis of high concns. of the rare metal(loid)?s and their modes of occurrence in coal basins are reviewed. Moreover, utilization prospects of these metal(loid)?s as byproduct coal deposits are evaluated. The extn. of these metal(loid) resources during coal exploitation and utilization would not only increase beneficial use of coal deposits themselves but also promote humanity's further movement on the "green road".

71.U12332
Smith M.P., Gleeson S.A., Yardley B.W.D. Hydrothermal fluid evolution and metal transport in the Kiruna District, Sweden: Contrasting metal behaviour in aqueous and aqueous–carbonic brines // Geochimica et Cosmochimica Acta. 2013. Vol. 102. P. 89–112.

Iron oxide-?copper-?gold (IOCG) deposits and Fe oxide-?apatite deposits from Norrbotten, Sweden, formed in similar settings, and in some cases IOCG mineralization overprinted Fe oxide-?apatite mineralization. Fluid inclusions in quartz veins cutting Fe oxide-?apatite deposits range in salinity from 33 to 37 wt.?% NaCl eq., and those in IOCG-?type deposits from 41 to 54 wt.?% NaCl eq. Min. trapping conditions for these inclusions are ?200-?300 MPa and 200-?300°C in the Fe oxide-?apatite bodies, and 250 to >300 MPa and 300-?500°C in the IOCG deposits. Deformed Cu-?Au deposits have similar early fluid characteristics, but contain complex secondary fluid inclusion assemblages including halite satd. (20-?30 wt.?% NaCl eq.)?, aq.-?carbonic (3-?13 wt.?% NaCl eq.; X(CO2) 0.17-?0.29) and CO2-?rich fluids. The aq.-?carbonic and carbonic inclusions are consistent with aq.-?carbonic fluid immiscibility at ?150 MPa. A secondary population, with a high Ca-?content occurs in all deposit types. The chem. compn. of these inclusions has been detd. by crush-?leach anal. and LA-?ICPMS. Halogen contents indicate a range of salinity sources with possible inputs from both magmatic and halite-?dissoln. brines. Element ratios suggest the alkali content of the fluid exceeded the buffer capacity of the host rocks. Iron and other transition metal contents correlate strongly with Cl concns., with secondary controls on soly. from pH, redox and temp. Copper and Ag contents are higher in lower salinity aq.-?carbonic brines (up to 5000 ppm Cu, 900 ppm Ag) than in the most saline brines (up to 2297 ppm Cu, 837 ppm Ag)?. This may reflect differences in metal source between deposit types, but is also consistent with the complexation of Cu by bisulfide in the lower salinity fluids. Late stage aq.-?carbonic fluid flux through the deformed deposits either introduced addnl. copper to the deposits, remobilized pre-?existing copper or both.

72.
Stachel T., Luth R.W. Diamond formation — Where, when and how? // Lithos. 2015. Vol. 220-223. P. 200–220.

Geothermobarometric calcns. for a worldwide database of inclusions in diamond indicate that formation of the dominant harzburgitic diamond assocn. occurred predominantly (90?%) under subsolidus conditions. Diamonds in eclogitic and lherzolitic lithologies grew in the presence of a melt, unless their formation is related to strongly reducing CHO fluids that would increase the solidus temp. or occurred at pressure-?temp. conditions below about 5 GPa and 1050 °C. Three quarters of peridotitic garnet inclusions in diamond classify as "depleted" due to their low Y and Zr contents but, based on LREEN-?HREEN ratios invariably near or greater than one, they nevertheless reflect re-?enrichment through either highly fractionated fluids or small amts. of melt. The trace element signatures of harzburgitic and lherzolitic garnet inclusions are broadly consistent with formation under subsolidus and supersolidus conditions, resp. Diamond formation may be followed by cooling in the range of ? 60-?180 °C as a consequence of slow thermal relaxation or, in the case of the Kimberley area in South Africa, possibly uplift due to extension in the lithospheric mantle. In other cases, diamond formation and final residence took place at comparable temps. or even assocd. with small temp. increases over time.Diamond formation in peridotitic substrates can only occur at conditions at least as reducing as the EMOD buffer. Evaluation of the redox state of 225 garnet peridotite xenoliths from cratons worldwide indicates that the vast majority of samples deriving from within the diamond stability field represent fO2 conditions below EMOD. Modeling reveals that less than 50 ppm fluid are required to completely reset the redox state of depleted cratonic peridotite to that of the fluid. Consequently, the overall reduced state of diamond stable peridotites implies that the last fluids to interact with the deep cratonic lithosphere were generally reducing in character. A further consequence of the extremely limited redox buffering capacity of cratonic peridotites is that redox reactions with infiltrating fluid?/melt likely cannot produce large diamonds or high diamond grades. Evaluating the shift in max. carbon content in CHO fluids during either isobaric cooling or ascent along a cratonic geotherm, however, reveals that isochem. pptn. of carbon from CHO fluids provides an efficient mode of diamond crystn. Since subsolidus fluids are permissible in harzburgites only, and supersolidus melts in lherzolite we suggest that CHO fluid metasomatism may explain the long obsd. close assocn. between diamonds and harzburgitic garnets. In the absence of thermodn. data we cannot evaluate if supersolidus carbonate-?bearing melts, stable at fO2 conditions below EMOD, would experience a similar decrease in max. carbon soly. during cooling or ascent along a geotherm. The absence of a clear assocn. between diamond and lherzolitic garnets, however, suggests that this is not the case. A very strong assocn. between diamond and eclogite likely relates to the fact that the transition from carbonate to diamond stable conditions occurs at redox conditions that are at least about 1 log unit more oxidizing than EMOD. At this time we cannot quant. evaluate the redox buffering capacity of cratonic eclogites but given their much higher Fe contents it has to be significantly higher than for peridotites. Alternatively, diamond in eclogite may ppt. directly from cooling carbonate-?bearing melts that may be too oxidizing to crystallize diamond in olivine-?bearing lithologies.

73.
Taranovic V. et al. Petrogenesis of the Ni–Cu–PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota // Lithos. 2015. Vol. 212-215. P. 16–31.

The Tamarack Intrusive Complex (TIC, 1105.6 ± 1.2 Ma) in NE Minnesota, was emplaced during the early stages of the development of the Midcontinent Rift System (MRS, "Early Stage": 1110-?1106 Ma)?. Country rocks of the TIC are those of the Paleoproterozoic Thomson Formation, part of the Animikie Group including sulfide-?bearing metasedimentary black shale. The magmatic system is composed of at least two principal mafic-?ultramafic intrusive sequences: the sulfide-?barren Bowl Intrusion in the south and the "dike" area intrusions in the north which host Ni-?Cu-?Platinum Group Elements (PGE) mineralization with up to 2.33?% Ni, 1.24?% Cu, 0.34 g?/t Pt, 0.23 g?/t Pd and 0.18 g?/t Au. Two distinct intrusive units in the "dike" area are the CGO (coarse-?grained olivine-?bearing) Intrusion, a sub-?vertical dike-?like body, and the overlying sub-?horizontal FGO (fine-?grained olivine-?bearing) Intrusion. Both intrusions comprise peridotite, feldspathic peridotite, feldspathic pyroxenite, melatroctolite and melagabbro. Massive sulfides are volumetrically minor and mainly occur as lenses emplaced into the country rocks assocd. with both intrusions. Semi-?massive (net-?textured) sulfides are distributed at the core of the CGO Intrusion, surrounded by a halo of the disseminated sulfides. Disseminated sulfides also occur in lenses along the base of the FGO Intrusion. Olivine compns. in the CGO Intrusion are between Fo89 and Fo82 and in the FGO Intrusion from Fo84 to Fo82. TIC intrusions have more primitive olivine compns. than that of olivine in the sheet-?like intrusions in the Duluth Complex (below Fo70)?, as well as olivine from the smaller, conduit-?related, Eagle and East Eagle Intrusions in Northern Michigan (Fo86 to Fo75)?. The FeO?/MgO ratios of the CGO and FGO Intrusion parental magmas, inferred from olivine compns., are similar to those of picritic basalts erupted during the early stages of the MRS formation. Trace element ratios differ slightly from other intrusions in the MRS, and are indicative of significant crustal contamination. Differences in textures, whole-?rock and mineral compns., and sulfide distribution are consistent with the emplacement of at least two distinct sulfide satd. magmatic pulses. Ni-?enrichment in the TIC indicates that sulfide satn. was attained prior to the sequestration of major proportions of Ni by olivine, possibly at a deeper chamber in the magmatic system. The addn. of crustal S from the Thomson Formation sulfidic country rocks is thought to have been the principal process which drove the early attainment of sulfide satn. in the magmas. The CGO Intrusion carried the greater abundance of sulfide liq., but both the CGO and FGO intrusive sequences represent the accumulation of dense silicate minerals and sulfide liq. in a conduit system. The genetic processes that were operative in the formation of Ni-?Cu-?PGE mineralization in the Tamarack Intrusive Complex appear to be typical of conduit-?style magmatic sulfide deposits assocd. with large continental basaltic provinces.

74.U12332
Tomkins A.G. Windows of metamorphic sulfur liberation in the crust: Implications for gold deposit genesis // Geochimica et Cosmochimica Acta. 2010. Vol. 74, № 11. P. 3246–3259.

Understanding the source of metamorphic sulfur is crit. to clarifying the complete cycle of ore genesis, from source to sink, for several mineral deposit types. A mass balance approach and the thermodn. computer programs THERMOCALC and PerpleX were used to constrain the pressure-?temp. range of pyrite breakdown to pyrrhotite (which liberates sulfur) in common metamorphic lithologies. The results suggest that most of the continental crust's metamorphic sulfur is liberated in a relatively narrow temp.-?pressure window corresponding to the terminal breakdown of chlorite at moderate to low pressures. This is because pyrite stability is controlled partly by temp. and pressure, and partly by the amt. of H2O present. During prograde metamorphism from the greenschist to the amphibolite facies, metamorphic H2O is produced primarily through chlorite breakdown in mafic to pelitic bulk compns. As temp. increases, more sulfur is required from pyrite to maintain equil. proportions of H2O, H2S and SO2 in the fluid, and in addn., progressively more sulfur is required at lower pressures. At low temps., little sulfur is required by metamorphic fluid released during initial chlorite breakdown, whereas at higher temps. coinciding with the terminal breakdown of chlorite, not only is more fluid present, but the fluid's sulfur requirement has also increased dramatically. In this way, metamorphic dehydration drives pyrite breakdown and generation of sulfur-?rich hydrothermal fluids at mesothermal conditions. Beyond the chlorite stability field there is minimal metamorphic fluid prodn., except at low pressures and high temps. where muscovite can break down without causing melting; conditions that are a long way from typical crustal geotherms. However, deformation also plays a key role in pyrite breakdown. Without deformation, small amts. of fluid in chem. communication with individual pyrite grains will quickly acquire equil. concns. of the sulfur species and minimal pyrite breakdown is necessary. Whereas during deformation, there may be a continuous fluid flux past pyrite grains, promoting ongoing sulfur liberation. In this way, periods of deformation may be the major sulfur-?liberating episodes during a metamorphic cycle. Since hydrothermal fluids are inherently buoyant and consequently tend to migrate upwards and towards cooler temps. through the crust, these results imply that orogenic gold deposits are most likely to form at lower-?amphibolite to prehnite-?pumpellyite facies conditions, and unlikely to form at higher temps. The pressure constraint on metamorphic sulfur liberation implies that tectonic settings that allow prograde metamorphism to follow low pressure pressure-?temp.-?time paths in an occasionally compressional or transpressional environment are necessary. Settings that promote extensive injection of felsic magma into a mid-?crust that contains a significant proportion of pyritic carbonaceous metasediment are shown to be ideal for orogenic gold deposit genesis. Inverted back-?arc basins are interpreted to be the most favorable of these.

75.U49394
Wang B. et al. Endogenic Au-Ag polymetallic ore deposits and ore-bearing potentiality of strata // Chinese Journal of Geochemistry. 2010. Vol. 29, № 4. P. 407–415.

The problem of ore-?bearing potentiality of the strata involves metallogenic theory and ore-?search orientation. Studies of the spatial distribution of endogenic Au-?Ag polymetallic ore deposits in North Hebei indicated that the strata in which ore deposits occurred range in age from Paleozoic, Proterozoic to Mesozoic. In addn. the ore deposits are characterized as being strata-?bound in nature. The arise and establishment of "extg." viewpoint may be attributed to the following three reasons: (1) influence by the idea of "ore-?source bed"; (2) limitation of anal. techniques in the 1980s' (esp. gold element)?; and (3) a small no. of samples (sampling locations were mostly disturbed by mineralization)?. Studies have shown that ore-?forming materials would most probably come from the deep interior of the Earth. Deep-?seated ore-?bearing materials including Au-?Ag polymetals were brought to the shallow levels by way of mantle plume-?mantle sub-?plume-?mantle branch structure multi-?stage evolution, finally leading to the formation of ore deposits.

76.U49394
Wang B. et al. Temporal-spatial distribution and ore-forming material source of gold, copper and silver polymetallic ore deposits in the Fuping mantle structure zone // Chinese Journal of Geochemistry. 2010. Vol. 29, № 3. P. 270–277.

This study was conducted following research on metallogenesis in the Zhangjiajie-?Xuanhua and East Hebei mantle branch structure zones. The Fuping mantle branch structure zone is one where Au, Cu and Ag polymetallic ore resources are concd. in North Hebei. However, there has existed a long-?standing controversy on the temporal-?spatial distribution of ore resources and their ore-?forming material sources. In terms of age dating and the comprehensive anal. of S, Pb, O, C and Si isotopes, it is considered that the temporal-?spatial distribution of ore resources in this mantle branch structure zone is obviously controlled by the Fuping mantle branch structure. In space there is developed such a metallogenic pattern as to be Ag, Pb and Zn polymetallic ore deposits with gold appearing inside and copper appearing outside. Metallogenesis is dated mainly at Yanshanian, the ore-?forming materials were derived predominantly from the deep interior of the Earth, and ore-?forming fluids were derived largely from Yanshanian magmatism.

77.
Wang Y., Zeng Q., Liu J. Rb-Sr Dating of Gold-bearing Pyrites from Wulaga Gold Deposit and its Geological Significance: Rb-Sr Dating for Wulaga Gold Deposit // Resource Geology. 2014. Vol. 64, № 3. P. 262–270.

Wulaga epithermal gold deposit is located in northeast China. Gold mineralization mainly occurs within the crypto-?explosive breccia belt of subvolcanic intrusion. Constraints on the precise timing of mineralization are of fundamental importance for understanding the ore genesis of the Wulaga gold deposit and its mineralization potential. Three hydrothermal stages have been identified: the early veiny quartz-?euhedral pyrite stage; the fine pyrite-?marcasite-?gray or black chalcedony stage; and the late carbonate-?pyrite stage. The Rb-?Sr dating of gold-?bearing pyrites from the fine pyrite-?marcasite-?gray or black chalcedony stage is 113.8 ± 4.4 Ma with an initial 87Sr?/86Sr ratio of 0.706346 ± 0.000019. The age of the gold deposit is consistent with the age of ore-?bearing volcanic (109-?113 Ma) and subvolcanic intrusion (103-?112 Ma) within the error limits, and the pyrite initial ratio has an identical value of 87Sr?/86Sr to subvolcanic intrusion (0.705547 ± 0.000012)?. These indicate that crystn. of the wall rock and epithermal gold mineralization was coeval and likely cogenetic. Moreover, a lot of epithermal gold deposits that formed in Early Cretaceous volcanic and subvolcanic intrusions have been discovered in recent years in Heilongjiang province. Combined with the studies of tectonic and magmatic activities, we propose that the formation of the Wulaga gold deposit might be caused by the heated circum-?flow water related to the volcanic-?subvolcanic intrusive hydrothermal event triggered by the ancient subduction of the Izanagi plate in the Early Cretaceous.

78.U49394
Wang Z. et al. Study on the evolution of ore-formation fluids for Au-Sb ore deposits and the mechanism of Au-Sb paragenesis and differentiation in the southwestern part of Guizhou Province, China // Chinese Journal of Geochemistry. 2013. Vol. 32, № 1. P. 56–68.

Ore deposits (occurrences) of Au, As, Sb, Hg, etc. distributed in Southwest Guizhou constitute the important portion of the low-?temp. metallogenic domain covering a large area in Southwest China, with the Carlin-?type Au and Sb deposits being the most typical ones. In this paper the Au and Sb ore deposits are taken as the objects of study. Through the petrog. anal., microthermomitric measurement and Raman spectrophic anal. of fluid inclusions in gangue minerals and research on the S and C isotopic compns. in the gold ore deposits we can reveal the sources of ore-?forming materials and ore-?forming fluids and the rules of ore fluid evolution. Ore deposits of Au, Sb, etc. are regionally classified as the products of ore fluid evolution, and their ore-?forming materials and ore fluids were probably derived mainly from the deep interior of the Earth. Fluid inclusion studies have shown that the temps. of Au mineralization are within the range of 170-?361°C,?the salinities are 0.35 wt?%-?8 wt?% NaCl eq.; the temps. of Sb mineralization are 129.4-?214°C and the salinities are 0.18 wt?%-?3.23 wt?% NaCl eq.; the ore-?forming fluid temps. and salinities tend to decrease progressively. In the early stage (Au metallogenic stage) the ore-?forming fluids contained large amts. of volatile components such as CO2, CH4, N2 and H2S, belonging to the H2O-?CO2-?NaCl fluid system; in the late stage (Sb metallogenic stage) the ore-?forming fluids belong to the Sb-?bearing H2O-?NaCl system. The primitive ore-?forming fluids may have experienced at least two processes of immiscibility: (1) when early ore-?bearing hydrothermal solns. passed through rock strata of larger porosity or fault broken zones, CO2, CH4, N2 would escape from them, followed by the release of pressure, resulting in pressure release and boiling of primitive homogenous fluids, thereafter giving rise to their phase sepn., thus leading to Au unloading and mineralization; and (2) in the late stage (Sb metallogenic stage ) a large vol. of meteoric water was involved in the ore-?forming fluids, leading to fluid boiling as a result of their encounter, followed by the drop of fluid temp. As a result, the dissoly. of Sb decreased so greatly that Sb was enriched and pptd. as ores. Due to differences in physic-?chem. conditions between Au and Sb ppts., Au and Sb were resp. pptd. in different structural positions, thus creating such a phenomenon of Au?/Sb paragenesis and differentiation in space.

79.
Wawryk C.M., Foden J.D. Fe-isotope fractionation in magmatic-hydrothermal mineral deposits: A case study from the Renison Sn–W deposit, Tasmania // Geochimica et Cosmochimica Acta. 2015. Vol. 150. P. 285–298.

We present 50 new iron isotopic analyses of source granite and mineral separates from the Renison tin deposit in western Tasmania. The aim of the study is to characterize the compn. of minerals within a tin deposit assocd. with a reduced, S-?type magma. We have analyzed bulk samples of granite, and separates of pyrrhotite, pyrite, arsenopyrite, magnetite, chalcopyrite and siderite by multi-?collector inductively coupled mass spectrometry. The isotopic compns. of mineral separates are consistent with theor. predictions of equil. fractionation based on M.ovrddot.ossbauer spectroscopy and other parametric calcns. Mineral-?mineral pairs yield temps. of formation that are in agreement with prior detailed fluid inclusion studies, but are spatially inconsistent with declining fluid temps. with distance from the causative intrusion, limiting the use of Fe isotopes as a potential geothermometer, at least in this case. Comparison of our data with published data from other deposits clearly demonstrates that pyrite, magnetite and chalcopyrite from the hottest ore fluids (>300-?400 °C) at Renison are isotopically heavier than minerals sampled from a deposit formed at similar temps., but assocd. with a more oxidized and less differentiated intrusion.

80.
WoldeGabriel G. et al. Characterization of cores from an in-situ recovery mined uranium deposit in Wyoming: Implications for post-mining restoration // Chemical Geology. 2014. Vol. 390. P. 32–45.

In-?situ recovery (ISR) of uranium (U) from sandstone-?type roll-?front deposits is a technol. that involves the injection of solns. that consist of ground water fortified with oxygen and carbonate to promote the oxidative dissoln. of U, which is pumped to recovery facilities located at the surface that capture the dissolved U and recycle the treated water. The ISR process alters the geochem. conditions in the subsurface creating conditions that are more favorable to the migration of uranium and other metals assocd. with the uranium deposit. There is a lack of clear understanding of the impact of ISR mining on the aquifer and host rocks of the post-?mined site and the fate of residual U and other metals within the mined ore zone. We performed detailed petrog., mineralogical, and geochem. analyses of several samples taken from about 7 m of core of the formerly the ISR-?mined Smith Ranch-?Highland uranium deposit in Wyoming. We show that previously mined cores contain significant residual uranium (U) present as coatings on pyrite and carbonaceous fragments. Coffinite was identified in three samples. Core samples with higher org. (> 1 wt.?%) and clay (> 6-?17 wt.?%) contents yielded higher 234U?/238U activity ratios (1.0-?1.48) than those with lower org. and clay fractions. The ISR mining was inefficient in mobilizing U from the carbonaceous materials, which retained considerable U concns. (374-?11,?534 ppm)?. This is in contrast with the deeper part of the ore zone, which was highly depleted in U and had very low 234U?/238U activity ratios. This probably is due to greater contact with the lixiviant (leaching soln.) during ISR mining.EXAFS analyses performed on grains with the highest U and Fe concns. reveal that Fe is present in a reduced form as pyrite and U occurs mostly as U(IV) complexed by org. matter or as U(IV) phases of carbonate complexes. Moreover, U-?O distances of ? 2.05 A were noted, indicating the potential formation of other poorly defined U(IV?/VI) species. We also noted a small contribution from U=O at 1.79 A, which indicates that U is partially oxidized. There is no apparent U-?S or U-?Fe interaction in any of the U spectra analyzed. However, SEM anal. of thin sections prepd. from the same core material reveals surficial U assocd. with pyrite which is probably a minor fraction of the total U present as thin coatings on the surface of pyrite.Our data show the presence of different structurally variable uranium forms assocd. with the mined cores. U assocd. with carbonaceous materials is probably from the original U mobilization that accumulated in the org. matter-?rich areas under reducing conditions during shallow burial diagenesis. U assocd. with pyrite represents a small fraction of the total U and was likely deposited as a result of chem. redn. by pyrite. Our data suggest that areas rich in carbonaceous materials had limited exposure to the lixiviant soln., continue to be reducing, and still hold significant U resources. Because of their limited access to fluid flow, these areas might not contribute significantly to post-?mining U release or attenuation. Areas with pyrite that are accessible to fluids seem to be more reactive and could act as reductants and facilitate U redn. and accumulation, limiting its migration.

81.U1045X
Wulff K. et al. Origin of Mineralizing Fluids of the Sediment-Hosted Navachab Gold Mine, Namibia: Constraints from Stable (O, H, C, S) Isotopes // Economic Geology. 2010. Vol. 105, № 2. P. 285–302.

The Navachab gold mine in the Damara belt of central Namibia is characterized by a polymetallic Au-?Bi-?As-?Cu-?Ag ore assemblage, including pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, bismuth, gold, bismuthinite, and bismuth tellurides. Gold is hosted by quartz-?sulfide veins and semi-?massive sulfide lenses that are developed in a near-?vertical sequence of shelf-?type metasedimentary rocks, including marble, calcsilicate rock, and biotite schist. The sequence has been intruded by abundant syntectonic lamprophyre, aplite, and pegmatite dikes, documenting widespread igneous activity coeval with mineralization. The majority of quartz from the veins has ?18O values of 14 to 15 per mil (V-?SMOW)?. The total variations in ?18O values of the biotite schist and calcsilicate rock are relatively small (12-?14‰)?, whereas the marble records steep gradients in ?18O values (17-?21‰)?, the lowest values being recorded at the vein margins. Despite this, there is no correlation between ?18O and ?13C values and the carbonate content of the rocks, indicating that fluid-?rock interaction alone cannot explain the isotopic gradients. In addn., the marble records increased ?13C values at the contact to the veins, possibly related to a change in the physicochem. conditions during fluid-?rock interaction. Gold is interpreted to have pptd. in equil. with metamorphic fluid (?18O = 12-?14‰; ?D = -?40 to -?60‰) at peak metamorphic conditions of ca. 550°C and 2 kbars, consistent with isotopic fractionations between coexisting calcite, garnet, and clinopyroxene in the alteration halos. The most likely source of the mineralizing fluid was a mid-?crustal fluid in equil. with the Damaran metapelites that underwent prograde metamorphism at amphibolite- to granulite-?facies grades. Although there is no isotopic evidence for the contribution of magmatic fluids, they may have been important in contributing to the overall hydraulic regime and high apparent geothermal gradients (ca. 80°C?/km-?1) in the mine area.

82.
Xiong G. et al. Trace element and REE geochemistry of the Ediacaran Doushantuo Formation from Fanjingshan area, northeast Guizhou province, China // Carbonates and Evaporites. 2014. Vol. 29, № 4. P. 363–394.

Trace and rare earth elements (REEs) geochem. of carbonate rocks of the Ediacaran Doushantuo Formation, northeast Guizhou province were studied to present spatio-?temporal variations of trace elements and REEs from two suites of different sedimentary facies, so as to discuss simultaneously differing palaeo-?environmental conditions during the deposition of Ediacaran carbonate formation. Results demonstrate that the depositional seawater of the Nongjing section is more oxygen-?depleted than those of the Tongluo section during the early Doushantuo period. For the whole Doushantuo Formation, the sedimentary water column of the lower Doushantuo Formation is much more oxygen deficient than those of the upper, and is the most anoxic in the middle formation, which is consistent with sedimentary model of the Doushantuo Formation in this area. Relative to av. marine carbonate, the depletion and enrichment of certain trace elements indicate that the sedimentary condition of the Doushantuo carbonates deposition was anoxic (the early)?-?oxic (the middle)?-?anoxic (the later)?, with more intensive volcanic and hydrothermal accompanying with lower palaeoproductivity. The North American shale composite-?normalized REE + Y patterns of Doushantuo carbonates from two sections are both characteristic of a slightly neg. Ce anomaly, pos. Eu anomaly and superchondritic Y?/Ho ratio. Geochem. characteristics of trace elements and REEs reveal that these carbonates of the Doushantuo Formation formed generally in an alternant anoxic-?oxic environment and a moderately stratified ocean with influx of high-?temp. hydrothermal fluids and volcanic material. Different from the stepwise and protracted oxidn., an anoxic-?oxic switching process of sedimentary water column with two episodic anoxic events had taken place, and would have contributed to a stimulus for increased evolution at that time.

83.
Xu C. et al. A case example of the importance of multi-analytical approach in deciphering carbonatite petrogenesis in South Qinling orogen: Miaoya rare-metal deposit, central China // Lithos. 2015. Vol. 227. P. 107–121.

The South Qinling orogen in central China hosts carbonatites occurring as stocks associated with syenites and collectively regarded as the Miaoya intrusive complex. The complex hosts economic resources of rare-earth elements (REE) and Nb. The Miaoya syenites are strongly metasomatized at the contact with the carbonatites and cross-cut by carbonate and felsic veinlets. Small oscillatory-zoned crystals of zircons from the syenites give a concordant U–Pb age of 147 ± 0.5 Ma, which differs significantly from the ages of both large magmatic zircon grains from the syenites and primary monazite from the carbonatites (766 Ma and 234 Ma, respectively). To account for the possibility that the Miaoya syenites are coeval and cogenetic with the carbonatites, the trace-element budget of both rock types was examined in detail. The Miaoya carbonatite contains primary REE-rich fluorapatite and monazite, which precipitated earlier than the rock-forming REE-poor calcite, indicating that the primary carbonatitic magma was rich in REE. The compositions of the parental syenitic and carbonatitic magmas, calculated on the basis of the trace-element composition of primary fluorapatite in the two rock suites, show that the carbonatitic magma contained higher Sr and REE (La–Tb), but lower Ba, Pb, Th, U, Nb and Ta levels in comparison with the syenitic melt. These differences are inconsistent with derivation of the Miaoya rocks from a homogeneous carbonate–silicate melt by immiscibility or crystal fractionation. It is therefore concluded that the carbonatitic magma at Miaoya was generated directly in the mantle. Emplacement of the carbonatites in the South Qinling orogen marked transition to a postorogenic regime, and was preceded by oceanic crust subduction and closure of the Mianlue Ocean in the Triassic. Our models show that melting of the Mianlue crust and up to 10 wt.% of sediments cannot produce the levels of REE enrichment observed in the Miaoya carbonatites. More complex models, involving recycling of the Mianlue oceanic crust and a REE-rich carbonate liquid from an old deep-seated mantle source are required to explain the observed trace-element characteristics of the Miaoya carbonatites.

84.U28275
Yamamoto J. et al. Thermal structure beneath Far Eastern Russia inferred from geothermobarometric analyses of mantle xenoliths: Direct evidence for high geothermal gradient in backarc lithosphere // Tectonophysics. 2012. Vol. 554–557. P. 74–82.

Based on pressure and temperature (P–T) information of mantle-derived xenoliths, this report describes a geotherm in Far Eastern Russia, which is situated in the backarc of volcanic chains in eastern Asia. The mantle xenoliths have abundant CO2 fluid inclusions. Accurate determination of the internal pressure of the CO2 fluid inclusions enables estimation of the depth provenance of the mantle xenoliths. The depth provenances obtained from five mantle xenoliths are correlated with equilibrium temperatures estimated using a geothermometer. Assuming that the correlation reflects the geotherm in this region, it corresponds to heat flow of around 100 mW/m2, which is comparable to the surface heat flow in the volcanic arc. Such high heat flow implies a thin lithosphere and high temperature of the shallower upper mantle. Backarc areas are universally characterized by both high surface heat flow and the occurrence of recent volcanic activities. Furthermore low seismic velocity anomaly is widely observed in the shallower upper mantle in the backarc, especially in eastern Asia. The present xenolith geotherm suggests that the seismic anomaly arises from high temperature of the shallower upper mantle. It would be direct evidence for warming of the lithospheric mantle and subsequent lithospheric thinning, which is likely attributable to asthenospheric upwelling.

85.U49394
Yan B. et al. Geochemical characteristics and metallogenesis of Carlin-type gold deposits in the Sandu-Danzhai metallogenic zone, Guizhou Province, China // Chinese Journal of Geochemistry. 2012. Vol. 31, № 3. P. 209–220.

Geochem. studies of the Paiting and Miaolong Carlin-?type gold deposits in the Sandu-?Danzhai metallogenic zone, Guizhou Province, have shown that the mineralized-?altered rocks show LREE-?enrichment patterns, generally displaying neg. Eu anomalies (?Eu = 0.51-?0.97) and non-?apparent neg. Ce anomalies (?Ce = 0.86-?0.99). Calcite and fluorite in relation with metallogenesis show MREE-?enrichment patterns, generally displaying rather weak neg. Eu anomalies (?Eu = 0.74-?0.93) and weak neg. Ce (?Ce = 0.70-?0.98) anomalies. The ?13CPDB values of carbon in calcite are -?1.61 to -?5.82‰, the ?18OSMOW values of oxygen are 13.97-?19.24‰, and the ?34SCDT values of sulfur in stibnite are 17.72-?21.68‰. In regard to ?D and ?18O, ore-?forming fluids possess the characteristics of metamorphic water. The process of metallogenesis of the Carlin-?type gold deposits is controlled by the Yanshanian tectonic activities. The Yanshanian movement promoted the migration and mobilization of metamorphic fluids in the extensively developed medium-?to high-?grade metamorphic rocks in this region, carrying primarily enriched gold and assocd. elements such as Hg, As, and Sb in the Sinian metamorphosed black shales and Lower Cambrian black shales. The ore-?forming fluids found their way into a suitable metallogenic environment along the fault zone, followed by gold pptn. to form gold deposits.

86.U12332
Zezin D.Y., Migdisov A.A., Williams-Jones A.E. The solubility of gold in H2O–H2S vapour at elevated temperature and pressure // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 18. P. 5140–5153.

This experimental study sheds light on the complexation of gold in reduced sulphur-bearing vapour, specifically, in H2O–H2S gas mixtures. The solubility of gold was determined in experiments at temperatures of 300, 350 and 365 °C and reached 2.2, 6.6 and 6.3 ?g/kg, respectively. The density of the vapour varied from 0.02 to 0.22 g/cm3, the mole fraction of H2S varied from 0.03 to 0.96, and the pressure in the cell reached 263 bar. Statistically significant correlations of the amount of gold dissolved in the fluid with the fugacity of H2O and H2S permit the experimental data to be fitted to a solvation/hydration model. According to this model, the solubility of gold in H2O–H2S gas mixtures is controlled by the formation of sulphide or bisulphide species solvated by H2S or H2O molecules. Formation of gold sulphide species is favoured statistically over gold bisulphide species and thus the gold is interpreted to dissolve according to reactions of the form:(A1) Au(s) + ( n + 1 ) H 2 S ( g ) = AuS · ( H 2 S ) n ( g ) + H 2 ( g ) (A2) Au(s) + H 2 S ( g ) + m H 2 O ( g ) = AuS · ( H 2 O ) m ( g ) + H 2 ( g ) Equilibrium constants for Reaction (A1) and the corresponding solvation numbers (KA1 and n) were evaluated from the study of Zezin et al. (2007). The equilibrium constants as well as the hydration numbers for Reaction (A2) (KA2 and m) were adjusted simultaneously by a custom-designed optimization algorithm and were tested statistically. The resulting values of log KA2 and m are ?15.3 and 2.3 at 300 and 350 °C and ?15.1 and 2.2 at 365 °C, respectively. Using the calculated stoichiometry and stability of Reactions (A1) and (A2), it is now possible to quantitatively evaluate the contribution of reduced sulphur species to the transport of gold in aqueous vapour at temperatures up to 365 °C. This information will find application in modelling gold ore-forming processes in vapour-bearing magmatic hydrothermal systems, notably those of epithermal environments.

87.U49394
Zhang M. et al. Study on the element geochemical charactersitics of the Shazi large-sized anatase ore deposit in Qinglong, Guizhou Province // Chinese Journal of Geochemistry. 2014. Vol. 33, № 3. P. 316–323.

The Shazi anatase ore deposit in Qinglong, Guizhou Province, is a large-?sized anatase deposit that has been recently explored. The characteristics of major oxides in the ore are similar to those of modern laterite weathering crust and laterite in the laterite-?type gold deposits in the western part of Guizhou Province. Studies on the REE characteristics of basalts and anatase ores in the study region showed that both of them do have extremely strong affinities. There are two groups of trace elements in the ores, i.e., Au-?Ag-?As-?Sb-?Hg-?Tl assocn. and Sc-?TiO2-?Cu-?Fe-?Mn assocn., reflecting that the formation of anatase ore is related to the formation of siliceous claystone at the early stage of eruption of the Emeishan basaltic magma. The siliceous claystones are the major country rocks for the formation of laterite-?type gold ores and anatase ores. In the region anatase ores are rich in Sc and the basalts enriched in Fe, Mn, Ti and Sc are the material source of metallogenesis.

88.
Zhang Z., Zuo R., Cheng Q. Geological Features and Formation Processes of the Makeng Fe Deposit, China: Formation process, Makeng Fe deposit // Resource Geology. 2015. Vol. 65, № 3. P. 266–284.

Recent studies have revealed that the Makeng Fe deposit is a skarn type deposit. However, the skarns in Makeng, occurring primarily between limestone and sandstone, are not typically assocd. with limestone and plutons. Different periods of intrusions, e.7. Hercynian mafic intrusions and Yanshanian (i.e. early Cretaceous) Dayang-?Juzhou granitic intrusion, occurred in the Makeng deposit district. In this study, the formation processes of the skarns and Fe mineralization are constrained by detailed fieldwork, petrol., geochronol., and geochem. Skarns and Fe mineralization intersecting the Hercynian mafic intrusions are obsd. in consecutive specimens from the 106# tunnel. They suggest that the skarn formation and Fe mineralization occurred after the Hercynian mafic intrusions and are related to the later Yanshanian Dayang-?Juzhou granitic intrusion. The geochronol. characteristics of weakly skarn-?altered diabases, the decreasing nature of Fe contents in altered diabase, and the major element compns. of pyroxenes and garnets also support that Hercynian mafic intrusions are strongly reformed by Yanshanian granitic magmas and the Fe migrated from mafic intrusion was responsible for formation of iron ore.

89.
Zhao K.-D. et al. Mineralogy, geochemistry and ore genesis of the Dawan uranium deposit in southern Hunan Province, South China // Journal of Geochemical Exploration. 2014. Vol. 138. P. 59–71.

The Dawan deposit in southern Hunan Province is one of the large-?scale metasedimentary rock-?hosted uranium deposits in China. Uranium orebodies occur mainly as big vein type and disseminated veinlet type, and are chiefly hosted within the Cambrian metasedimentary rocks, but some small ore veins can extend into the Jurassic Jinjiling granites. The dominant uranium ore minerals include pitchblende and coffinite. Coffinite often replaces and rims the pre-?existing pyrite, and pitchblende occurs as veinlets and disseminated grains filled the fracture zones of metasedimentary rocks. It is suggested that the coffinite was most likely formed by initial redn. of U6 + to U4 + by pyrite from an oxidized Si-?rich fluid at an early mineralization stage, whereas the pitchblende may have formed at a later stage in a relatively reduced and Si-?poor fluid. Chlorite alteration is widespread and is inter-?grown with pitchblende in ores. Electron microprobe anal. reveals that the chlorite belongs to Mg-?rich clinochlore, which is different to the Fe-?rich chlorite in most granite-?hosted and volcanic rock-?hosted uranium deposits in South China. The hydrothermal alteration temps. were estd. to be 189-?227 °C according to chlorite geothermometer. The ores show similar trace element characteristics to those of metasedimentary wall-?rocks, but different from those of the Jinjiling granites. Neg. Ce anomalies of the ores indicate an oxidized hydrothermal fluid, which was most likely derived from circulated meteoric water. The ?Nd(t) values of the ores are lower than those of the Jinjiling granites, but fall into the range of the basement strata. Sulfur isotopic compns. of hydrothermal pyrites vary from - 9.5‰ to - 7.7‰, similar to those from the wall-?rocks, which implies that the sulfur in ore-?forming fluids was mainly derived from diagenetic sulfur in the sedimentary strata. Pyrite in ores shows highly radiogenic lead isotopic compns. (206Pb?/204Pb = 19.684-?89.234 and 207Pb?/204Pb = 15.722-?19.683)?. In a plot of 206Pb?/204Pb vs. 207Pb?/204Pb, the data show a good linear array and yield an isochron age of 479 ± 69 Ma (MSWD = 1.6)?, which is much older than the granites but relatively close to the age of the host metasedimentary strata, indicating that the uranium source was probably derived from the wall-?rock strata. It is suggested that the Dawan deposit is a hydrothermally reworked uranium deposit (referred to as the carbonaceous-?siliceous-?pelitic rock type by many Chinese geologists) with a close relationship with the host metasedimentary rocks. The Dawan deposit has no genetic relationship to the Jinjiling granite, contrary to what was previously suggested, and therefore the exploration in this area should focus on the conjunct occurrence of the Cambrian metasedimentary rocks rich in org. carbon and pyrite and the tectonic faulting which fractured and brecciated the strata.

90.
Zhengjie Q. et al. Fluid Inclusion and Carbon-Oxygen Isotope Studies of the Hujiayu Cu Deposit, Zhongtiao Mountains, China: Implications for Syn-metamorphic Copper Remobilization // Acta Geologica Sinica-English Edition. 2015. Vol. 89, № 3. P. 726–745.

The Hujiayu Cu deposit, representative of the HuBi-type Cu deposits in the Zhongtiao Mountains district in the southern edge of the North China Craton, is primarily hosted in graphite-bearing schists and carbonate rocks. The ore minerals comprise mainly chalcopyrite, with minor sphalerite, siegenite [(Co, Ni)(3)S-4], and clausthalite [Pb(S,Se)]. The gangue minerals are mainly quartz and dolomite, with minor albite. Four fluid inclusion types were recognized in the chalcopyrite-pyrite-dolomite-quartz veins, including CO2-rich inclusions (type I), low-salinity, liquid-dominated, biphase aqueous inclusions (type II), solid-bearing aqueous inclusions (type III), and solid-bearing aqueous-carbonic inclusions (type IV). Type I inclusion can be further divided into two sub-types, i.e., monophase CO2 inclusions (type Ia) and biphase CO2-rich inclusions (with a visible aqueous phase), and type III inclusion is divided into a subtype with a halite daughter mineral (type IIIa) and a subtype with multiple solids (type IIIb). Various fluid inclusion assemblages (FIAs) were identified through petrographic observations, and were classified into four groups. The group-1 FIA, consisting of monophase CO2 inclusions (type Ia), homogenized into the liquid phase in a large range of temperatures from -1 to 28 degrees C, suggesting post-entrapment modification. The group-2 FIA consists of type Ib, IIIb and IV inclusions, and is interpreted to reflect fluid immiscibility. The group-3 FIA comprises type II and IIIa inclusions, and the group-4 FIA consists of type II inclusions with consistent phase ratios. The group-1 and group-2 FIAs are interpreted to be entrapped during mineralization, whereas group-3 and group-4 FIAs probably represent the post-mineralization fluids. The solid CO2 melting temperatures range from -60.6 to 56.6 degrees C and from -66.0 to -63.4 degrees C for type Ia and type IV inclusions, respectively. The homogenization temperatures for type II inclusions range from 132 to 170 degrees C for group-3 FIAs and 115 to 219 degrees C for group-4 FIAs. The halite melting temperatures range from 530 to 562 degrees C for type IIIb and IV inclusions, whereas those for type IIIa inclusions range from 198 to 398 degrees C. Laser Raman and SEM-EDS results show that the gas species in fluid inclusions are mainly CO2 with minor CH4, and the solids are dominated by calcite and halite. The calcite in the hosting marble and dolomite in the hydrothermal veins have C-13(V-PDB) values of -1.2 to 1.2 parts per thousand and -1.2 to -6.3 parts per thousand, and O-18(V-SMOW) values of 14.0 to 20.8 parts per thousand and 13.2 to 14.3 parts per thousand, respectively. The fluid inclusion and carbon-oxygen isotope data suggest that the ore-forming fluids were probably derived from metamorphic fluids, which had reacted with organic matter in sedimentary rocks or graphite and undergone phase separation at 1.4-1.8 kbar and 230-240 degrees C, after peak metamorphism. It is proposed that the Hujiayu Cu deposit consists of two mineralization stages. The early stage mineralization, characterized by disseminated and veinlet copper sulfides, probably took place in an environment similar to sediment-hosted stratiform copper mineralization. Ore minerals formed in this precursor mineralization stage were remobilized and enriched in the late metamorphic hydrothermal stage, leading to the formation of thick quartz-dolomite-sulfides veins.

91.U12332
Zhong H. et al. Rhenium–osmium isotope and platinum-group elements in the Xinjie layered intrusion, SW China: Implications for source mantle composition, mantle evolution, PGE fractionation and mineralization // Geochimica et Cosmochimica Acta. 2011. Vol. 75, № 6. P. 1621–1641.

The Xinjie mafic–ultramafic layered intrusion in the Emeishan large igneous province (ELIP) hosts Cu–Ni–platinum group element (PGE) sulfide ore layers within the lower part and Fe–Ti–V oxide-bearing horizons within the middle part. The major magmatic Cu–Ni–PGE sulfide ores and spatially associated cumulate rocks are examined for their PGE contents and Re–Os isotopic systematics. The samples yielded a Re–Os isochron with an age of 262 ± 27 Ma and an initial 187Os/188Os of 0.12460 ± 0.00011 (?Os(t) = ?0.5 ± 0.1). The age is in good agreement with the previously reported U–Pb zircon age, indicating that the Re–Os system remained closed for most samples since the intrusion emplacement. They have near-chondritic ?Os(t) values ranging from ?0.7 to ?0.2, similar to those of the Lijiang picrites and Song Da komatiites. Exceptionally, two samples from the roof zone and one from upper sequence exhibit radiogenic ?Os(t) values (+0.6 to +8.6), showing minor contamination by the overlying Emeishan basalts. The PGE-rich ores contain relatively high PGE and small amounts of sulfides (generally less than 2%) and the abundance of Cu and PGE correlate well with S, implying that the distribution of these elements is controlled by the segregation and accumulation of a sulfide liquid. Some ore samples are poor in S (mostly <800 ppm), which may due to late-stage S loss caused by the dissolution of FeS from pre-existing sulfides through their interaction with sulfide-unsaturated flowing magma. The combined study shows that the Xinjie intrusion may be derived from ferropicritic magmas. The sharp reversals in Mg#, Cr/FeOT and Cr/TiO2 ratios immediately below Units 2–4, together with high Cu/Zr ratios decreasing from each PGE ore layer within these cyclic units, are consistent with multiple magma replenishment episodes. The sulfides in the cumulate rocks show little evidence of PGE depletion with height and thus appear to have segregated from successive inputs of fertile magma. This suggests that the Xinjie intrusion crystallized from in an open magma system, e.g., a magma conduit. The compositions of the disseminated sulfides in most samples can be modeled by applying an R factor (silicate–sulfide mass ratio) of between 1000 and 8000, indicating the segregation of only small amounts of sulfide liquid in the parental ferropicritic magmas. Thus, continuous mixing between primitive ferropicritic magma and differentiated resident magma could lead to crystallization of chromite, Cr-bearing magnetite and subsequently abundant Fe–Ti oxides, thereby the segregation of PGE-rich Cu-sulfide. When considered in the light of previous studies on plume-derived komatiites and picrites worldwide, the close-to-chondritic Os isotopic composition for most Xinjie samples, Lijiang picrites and Song Da komatiites suggest that the ferropicritic magma in the ELIP were generated from a plume. This comprised recycled Neoproterozic oceanic lithosphere, including depleted peridotite mantle embedded with geochemically enriched domains. The ascending magmas thereafter interacted with minor (possibly <10%) subducted/altered oceanic crust. This comparison suggests that the komatiitic melts in the ELIP originated from a greater-than normal degree of melting of incompatible trace element depleted, refractory mantle components in the plume source.

92.U49394
Zhu J. et al. U-Pb zircon geochronology, geochemistry and kinetics of the Huaniushan A-type granite in Northwest China // Chinese Journal of Geochemistry. 2012. Vol. 31, № 1. P. 85–94.

The Huaniushan granite is located at the Beishan orogenic belt, northwestern China. At the contact zone between the granite and marble, a hydrothermal Pb-?Zn and skarn Au deposit is formed. LA-?ICP-?MS zircon U-?Pb dating yielded a weighted mean 206Pb?/238U age of 229.5±2.6 Ma (MSDW=0.93) for the Huaniushan granite, implying its Late Triassic intrusion. Geochem. analyses show that the Huaniushan granite is enriched in Si, K, Na, and REE, and depleted in Mg and Ca, with contents of SiO2 (70.8?% to 74.4?%)?, Na2O+K2O (8.8?% to 10.2?%)?, CaO (0.93?% to 1.44?%)?, and MgO (0.14?% to 0.48?%)?. REE is characterized by obvious neg. Eu anomaly. Rb, Th, U, K, Pb, Nb, Zr and Hf elements are rich in the granite while Ba, Sr, P, Ti and Eu are deplete. The granite has a high (Zr+Nb+Ce+Y) abundance and 104 Ga?/Al ratios. Petrol., major and trace elements data all indicate that the Huaniushan granite is A-?type granite which intruded in a post-?collisional extensional tectonic setting. The magma was dominantly sourced from partial melting of crustal intermediate-?felsic igneous rocks. Intensive magmatic activities and Au-?Cu-?Mo mineralization occurred throughout the Beishan orogenic belt during the period from ca. 240 to 220 Ma.

93.
Zhu W.-G. et al. Platinum-group minerals and tellurides from the PGE-bearing Xinjie layered intrusion in the Emeishan Large Igneous Province, SW China // Mineralogy and Petrology. 2010. Vol. 98, № 1-4. P. 167–180.

The Xinjie layered intrusion is one of a no. of major ultramafic-?mafic bodies hosting Fe-?Ti-?V ore deposits and Cu-?Ni-?PGE sulfide ore deposits in the Pan-?Xi (Panzhihua-?Xichang) area of the Sichuan Province, SW China. The Xinjie ultramafic-?mafic layered intrusion, genetically related to the Permian plume-?related Emeishan flood basalts, consists of three lithol. cycles, each representing a sequence from ultramafic to mafic-?felsic compn. The basal part of the intrusion is composed of three lithol. units, namely, the Marginal Unit (MU)?, Peridotite Unit (PeU) and Pyroxenite Unit (PyU)?. In the present study, three major PGE-?mineralized Cu-?Ni sulfide layers were discovered within the Marginal and Pyroxenite Units. The major base-?metal sulfides (BMS) comprise chalcopyrite, pyrrhotite, and pentlandite. Detailed microscopic and microprobe analyses revealed the presence of the sperrylite and Pd-?Pt-?Bi-?Te minerals (merenskyite, moncheite, and michenerite)?. These PGMs are commonly assocd. with the BMS, or magnetite coexisting with BMS in the PGE-?enriched layers. The 1:1 substitution between Pt and Pd, as well as between Te and Bi, confirms the complete solid-?soln. series between moncheite and merenskyite. The textural assocn. of the PGMs with BMS and Fe-?Ti oxides (magnetite) suggests that the PGMs may have crystd. slightly later than the hosting magnetite and BMS. The formation of magnetite may have played an important role in producing the sulfur-?satd. melt and the PGEs thus concd. in the sulfide liq. during the crystn. history. It is therefore suggested that the Cu-?Ni-?PGE-?bearing layers in the basal part of the Xinjie intrusion were generated by magma evolution processes.

94.001573
Абрамов Б.Н. Ключевское золоторудное месторождение: условия формирования, петрогеохимические особенности пород и руд (Восточное Забайкалье) // Доклады Академии Наук. 2015. Т. 464. № 1. С. 85-90.

Установлено, что магматические очаги интрузий амуджиканского комплекса (J3) имели близкие значения степени дифференциации магматических очагов и функционировали на глубинах, соответствующих нижней континентальной коре. Образование эксплозивных брекчий проходило во все периоды рудного процесса. Магматические очаги ранних брекчий функционировали на значительных глубинах. Поздние брекчии имеют карбонатный цемент и характеризуются повышенными содержаниями РЗЭ.

95.001573
Алексеев В.И., Марин Ю.Б. Вольфрамовые акцессорные минералы в литий-фтористых гранитах Дальнего Востока России // Доклады Академии Наук. 2014. Т. 458. № 3. С. 323–326.

96.001573
Аранович Л.Я., Прокофьев В.Ю., Перцев А.Н. и др. Гранитный расплав, обогащенный K2O, в Срединно-Атлантическом хребте на 13°34 с.ш.: состав и происхождение по данным анализа расплавных включений и минералов габбро-плагиогранитной ассоциации // Доклады Академии Наук. 2015. Т. 460. № 6. С.691-696.

97.001573
Аристов В.В., Прокофьев В.Ю., Имамендинов Б.Н. и др. Особенности рудообразования на золото-кварцевом месторождении Дражное (Восточная Якутия, Россия) // Доклады Академии Наук. 2015. Т. 464. № 1. С. 65-70.

Термобарогеохимические исследования показали, что кварц месторождения сформирован в мезотермальных условиях на глубинах 34 км из углекислотно-водных флюидов с широкими вариациями солености, содержащих в небольшом количестве метан. По составу вытяжек различаются гидрокарбонатно-натриевый флюид, сильно разбавленный, а также поздний сульфатно-гидрокарбонатно-натриевый с кальцием флюид с повышенной соленостью. Отложение рудных минералов происходило в термостатированных условиях при гетерогенизации флюидов за счет вероятного резкого снижения давления и смешения растворов различного генезиса. Метаморфические процессы, связанные с раннеколлизионным этапом, не оказывают существенного влияния на состав и перспективность золоторудной минерализации.

98.001200
Боровиков А.А., Бульбак Т.А., Борисенко А.С. и др. Поведение рудных элементов в окисленных хлоридных и карбонатно-хлоридно-сульфатных гетерофазных флюидах Cu-Mo(Au)-порфировых месторождений ( по экспериментальным данным) // Геология и геофизика. 2015. Т. 56. № 3. С. 557–570.

Совмещение в пространстве и близость времени образования Cu-Mo-порфировой магматогенной и эпитермальной золоторудной минерализации объясняется наличием генетической связи между процессами образования магматогенного порфирового и эпитермального оруденения. Одной из причин этой генетической связи может быть генерация порфировой рудно-магматической системой металлоносных флюидов, характеризующихся различной геохимической специализацией, при участии которых формируются магматогенные Cu-Mo-(Au)-порфировые и ассоциированные с ними золоторудные эпитермальные месторождения. Методом синтеза флюидных включений в кварце проведено экспериментальное изучение поведения Cu, Mo, W, Sn, Au, As, Sb, Te, Ag, Bi в гетерофазных флюидах, по составу и агрегатному состоянию близких к природным рудообразующим флюидам Cu-Mo-(Au)-порфировых месторождений. Установлено, что при температуре 700 °С понижение давления от 117 до 106 МПа приводит к значительному обогащению газовой фазы гетерофазного хлоридного флюида Au, As, Sb и Bi. Для карбонатно-хлоридно-сульфатных флюидов выявлено гетерофазное состояние при температуре 600 °С и давлении 100-90 МПа, характеризующее равновесие жидкая высококонцентрированная карбонатно-сульфатная фаза-жидкая хлоридная фаза-малоплотная газовая фаза. Понижение давления гетерофазного карбонатно-хлоридно-сульфатного флюида приводит к заметному обогащению его хлоридной фазы Cu, Mo, Fe, W, Ag, Sn, Sb и Zn относительно карбонатно-сульфатной фазы. Процессы перераспределения рудных элементов между отдельными фазами гетерофазных флюидов могут рассматриваться как модель генерации металлоносных хлоридных флюидов, которая реализуется в природных условиях при формировании Cu-Mo(Au)-порфировых месторождений, а также генерации газообразных флюидов, поставляющих Au, Te, As и другие рудные элементы к месту образования эпитермальной Au-Cu и Au-Ag минерализации.

99.001573
Знаменский С.Е., Пучков В.Н., Мичурин С.В. Источники рудообразующих флюидов и условия формирования орогенных месторождений золота зоны главного Уральского разлома на Южном Урале // Доклады Академии Наук. 2015. Т. 464. № 3. С. 313-316.

Рассмотрены результаты анализа стабильных изотопов серы, углерода и кислорода в минералах и структурных исследований орогенных месторождений золота, расположенных в углеродосодержащих толщах зоны Главного Уральского разлома на Южном Урале. Установлено, что формирование орогенного золотого оруднения происходило на двух основных стадиях позднепалеозойских коллизионных деформаций: ранней надвигообразования и поздней сдвигообразования. Ведущую роль в гидротермальных рудообразующих системах, продуцировавших месторождения, на первой из них играли флюиды метаморфогенного, а на второй магматогенного происхождения.

100.001573
Котов А.Б., Владыкин Н.В., Ларин А.М. и др. Новые данные о возрасте оруденения уникального Катугинского редкометального месторождения (Алданский щит) // Доклады Академии наук. 2015. Т. 463. № 2. С. 187-191.

101.001573
Куйбида М.Л., Крук Н.Н., Шокальский С.П. и др. Надсубдукционные плагиограниты рудного Алтая: возраст и особенности состава // Доклады Академии Наук. 2015. Т. 464. № 3. С. 317-322.

Представлены результаты геологических, геохимических, изотопно-геохронологических исследований древнейших плагиогранитов Рудного Алтая. Установлено, что образование рассматриваемых плагиогранитов произошло в начале среднего девона (395-387 млн лет) и было синхронно с масштабным проявлением надсубдукционного вулканизма, сопровождавшегося формированием многочисленных медно-полиметаллических месторождений. Геохимические характеристики плагиогранитов обнаруживают высокую степень сходства их составов с субвулканическими риолитами и риодацитами мельнично-сосновской свиты в Рудном Алтае (эмс-эйфель), что свидетельствует об их комагматичности.

102.001573
Смирнов С.З. , Бортников Н.С. и др. Составы расплавов и флюидный режим кристаллизации редкометальных гранитов и пегматитов Тигриного Sn-W-месторождения (Приморье) // Доклады Академии Наук. 2014. Т. 456. № 1. С. 95–100.

103.009109
Трейвус Е.Б., Силаев В.И. Новые данные о минералах из хрусталеносного месторождения Додо (Приполярный Урал) // Мінералогічний журнал. 2014. Т. 36. № 1 (179). С. 34-45.

Приведены результаты химического и гониометрического изучения кристаллов титанита, апатита и апофиллита из хрусталеносного месторождения Додо на Приполярном Урале. Двойник титанита отличается меньшим числом простых форм, чем это установлено для данного минерала в других хрусталеносных жилах этого района. Наряду с этим на исследованном кристалле выявлены две простые формы, неизвестные ранее для титанита уральских месторождений. Таблитчатый облик и пинакоидально-дипирамидальный габитус изученного кристалла апатита близки к описанным ранее для месторождений этого района и типичны для апатита из низкотемпературных кварцевых жил. Сделан вывод о ромбической сингонии рассмотренной разновидности апофиллита на основании гониометрического изучения и особенностей скульптуры его граней и его возможном типоморфизме.

104.001573
Хромых С.В., Соколова Е.Н., Смирнов С.З. и др. Геохимия и возраст редкометальных дайковых поясов Восточного Казахстана // Доклады Академии Наук. 2014. Т. 459. № 5. С. 612-617.

На главную              К списку выставок