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Understanding the key timings related to petroleum evolution is crucial for optimizing exploration targets and assessing oil/gas resources, attract petroleum geologists’ attention worldwide. Recently, hydrocarbon (oil and bitumen) Re–Os isotope dating has been innovatively applied to constrain the timing related to oil/gas generation, however, the resulting Re–Os isochron ages can be complex and challenging to interpret. This study utilizes various geochemical and geochronological data from Sinian to Cambrian natural gas reservoirs in the Sichuan Basin to reconstruct the hydrocarbon evolution process and discuss the significance of different bitumen Re–Os dating results. The gas accumulation in the SinianCambrian reservoirs experienced four stages of evolution: (1) initial oil generation during the Ordovician to Silurian periods, (2) secondary oil generation during the Triassic period, (3) gas generation through thermal cracking of liquid oil from the Jurassic to Cretaceous periods, and (4) gas reservoir redistribution since the late Cretaceous. The Re–Os dates (ca. 485 Ma) of low maturity and biodegraded bitumen from the western Sichuan Basin record the oil generation during the Ordovician before the Caledonian tectonic event. The Re–Os dates (ca.184–128 Ma) of highly mature bitumen associated with MVT Pb–Zn deposits in northern Sichuan Basin provide insights into both liquid oil-cracking and thermochemical sulfate reduction (TSR) processes. The complex Re–Os dates (ca.414 Ma, ca.154 Ma) of highly mature bitumen from the central Sichuan Basin may represent different periods related to either oil or gas generation. Future studies should explore the genetic type, maturity, thermal cracking, or TSR degrees of bitumen to better understand the significance of Re–Os dates. [ABSTRACT FROM AUTHOR]

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Quartz-vein-type copper deposits were discovered in SN-trend ore-bearing structures in north-west Dayaoshan, Guangxi. Lack of reports on the precise metallogenic age of these deposit has become a bottleneck in metallogenic research in this area. In this study, the quartz vein-type copper mine in Longwei area of Jinxiu was selected as the research object. Fresh illite samples in the fault gouges and ore samples were collected for testing and analysis. Based on the Re-Os isotope dating study, the age of pyrite isochron, belonging to the Caledonian period, was determined to be 417 ± 25 Ma, whereas that of chalcopyrite isochron belonging to the Indosinian period, was found to be 243 ± 18 Ma. Pyrite crystallized considerably earlier than chalcopyrite. The obtained EPMA data were combined with rock mineralogical analysis data, Metasomatous mineral pyrite and metasomatic mineral chalcopyrite were identified to have originated from different hydrothermal systems. In the Indosinian period, copper deposits in the Longwei area underwent pyrite crystallization, pyrite fragmentation, copper-bearing hydrothermal filling, and metasomatism, consolidating and forming minerals. The study determined the mineralisation time and ore sources of copper deposits in the Longwei area. The study provides evidence for the existence of Indosinian hydrothermal activities in the north-western Dayaoshan area. [ABSTRACT FROM AUTHOR]

The Xiaoqinling area is located in the eastern part of the Qinling Orogen and experiences early and late Mesozoic gold mineralization controlled by structural deformation. The relationship between the two stages of mineralization and the orogenic process of the Qinling Orogen is unclear. We investigated the deformation and alteration of E-W striking veins in the Xiaoqinling area. The geometric features revealed that all the veins developed within the E-W-striking Guanyintang brittle-ductile shear zone. The vein was subparallel to the shear zone, dipped at 30°-60°, and had a wave-like appearance. The Guanyintang shear zone underwent three deformation stages: sinistral shearing (D1), dextral thrusting (D2), and sinistral normal faulting (D3). The development of ore- bearing quartz veins was controlled by deformation during D2, and the auriferous pyrite and minor chalcopyrite developed along the shear foliations. Re-Os dating of the molybdenite revealed a well-constrained isochron age of 230.2 ± 2.6 Ma, indicating the E-W striking shear zone developed in Late Triassic. This early Mesozoic shearing deformation in Xiaoqinling represents the early Mesozoic metallogenesis is correlated with the collisional orogeny of the Qinling orogen. [ABSTRACT FROM AUTHOR]

Geological observations and U–Pb dating of zircons from intrusions of the Yana–Kolyma gold province constrain the age of orogenic gold deposits to the time interval between 150 ± 3Ma and 108 ± 1 Ma. The Natalka deposit is the largest key deposit in the gold province. We determined the age of mineralization as the Valanzhinian (136 ± 1 to 132 ± 2 Ma) by 40Ar/39Ar dating of muscovite and by Re–Os dating of arsenopyrite and native gold. There are no known manifestations of magmatism of this age in the province, therefore, we conclude that the formation of gold–quartz mineralization is very likely related to metamorphism and metasomatism triggered by regional-scale shear deformations. [ABSTRACT FROM AUTHOR]

The Dahongshan Fe‐Cu (‐Au) deposit is a superlarge deposit in the Kangdian metallogenic belt, southwestern China, comprising approximately 458 Mt of Fe ores (40% Fe) and 1.35 Mt Cu. Two main types of Fe‐Cu (‐Au) mineralization are present in the Dahongshan deposit: (1) early submarine volcanic exhalation and sedimentary mineralization characterized by strata‐bound fine‐grained magnetite and banded Fe‐Cu sulfide (pyrite and chalcopyrite) hosted in the Na‐rich metavolcanic rocks; (2) late hydrothermal (‐vein) type mineralization characterized by Fe‐Cu sulfide veins in the hosted strata or massive coarse‐grained magnetite orebodies controlled by faults. While previous studies have focused primarily on the early submarine volcanic and sedimentary mineralization of the deposit, data related to late hydrothermal mineralization is lacking. In order to establish the metallogenic age and ore‐forming material source of the late hydrothermal (‐vein) type mineralization, this paper reports the Re‐Os dating of molybdenite from the late hydrothermal vein Fe‐Cu orebody and H, O, S, and Pb isotopic compositions of the hydrothermal quartz‐sulfide veins. The primary aim of this study was to establish the metallogenic age and ore‐forming material source of the hydrothermal type orebody. Results show that the molybdenite separated from quartz‐sulfide veins has a Re‐Os isochron age of 831 ± 11 Ma, indicating that the Dahongshan Fe‐Cu deposit experienced hydrothermal superimposed mineralization in Neoproterozoic. The molybdenite has a Re concentration of 99.7–382.4 ppm, indicating that the Re of the hydrothermal vein ores were primarily derived from the mantle. The δ34S values of sulfides from the hydrothermal ores are 2‰–8‰ showing multi‐peak tower distribution, suggesting that S in the ore‐forming period was primarily derived from magma and partially from calcareous sedimentary rock. Furthermore, the abundance of radioactive Pb increased significantly from ore‐bearing strata to layered and hydrothermal vein ores, which may be related to the later hydrothermal transformation. The composition of H and O isotopes within the hydrothermal quartz indicates that the ore‐forming fluid is a mixture of magmatic water and a small quantity of water. These results further indicate that the late hydrothermal orebodies were formed by the Neoproterozoic magmatic hydrothermal event, which might be related to the breakup of the Rodinia supercontinent. Mantle derived magmatic hydrothermal fluid extracted ore‐forming materials from the metavolcanic rocks of Dahongshan Group and formed the hydrothermal (‐vein) type Fe‐Cu orebodies by filling and metasomatism. [ABSTRACT FROM AUTHOR]

The traditional organic index can be greatly affected in the areas with high thermal evolution degree whilst combination of REE for oil-source correlation will improve the results. In addition, Re-Os dating is a quantitative method of geochronology, but the significance of the test results is quite controversial. In this paper, REE geochemical analysis and Re-Os dating of bitumen in the Banjie paleo-oil reservoir is carried out. The REE distribution pattern of bitumen was compared with that of the main source rocks in the area using the method of grey correlation. Results show that the ΣREE of bitumen in the Banjie paleo-oil reservoir is low, and the fractionation of light and heavy REEs is obvious, showing a weak negative Ce anomaly and an obvious negative Eu anomaly, which indicates that the bitumen was formed in a reducing environment and has not experienced any strong weathering or leaching. The REE distribution mode belongs to the right-leaning mode of LREE enrichment. The REE distribution pattern curve is similar to that of Devonian source rocks in this area, indicating a genetic relationship. The results of Re-Os dating show that the Re-Os model age of bitumen in the Banjie paleo-oil reservoir ranges mainly from (203.6±1.1) Ma to (238.5±4.2) Ma, with an average of (224.8±3.3) Ma (n=7). The last factor which disturbed the Re-Os system of the bitumen is the process of bitumen generation. The model age represents the age of bitumen formation in the Banjie paleo-oil reservoir, when oil was cracked into gas.

The discovery of Santonggou manganese deposit is an important breakthrough in manganese prospecting in East Kunlun. The detrital zircon from two siltstone samples of Santonggou manganese deposit were used for LA-ICP-MS U-Pb dating. The detrital zircon U-Pb ages are ranging from(1 497±17)Ma to(427±4)Ma, with two peaks of 441 and 473 Ma, respectively. The youngest detrital zircon age is(427±4)Ma, indicating the age of Santonggou manganese deposit is later than 427 Ma. The age peaks of detrital zircon are consisting with Early Paleozoic Naji Tal Group, and indicate that the detritals provenance are the middle strata of Naji Tal Group. The Re-Os isochron age of black shale from Santonggou manganese deposits are(387.4±6.2)Ma, indicating that the age of burial diagenesis is Middle Devonian, and the initial precipitation of manganese is earlier. Based on isotopic dating results, the sedimentary age of Santonggou manganese deposit is limited in Late Silurian-Middle Devonian. The relationship between the mineralization of Santonggou manganese deposit and the subduction of Proto-Tethys ocean is discussed based on the main view about genesis of Early Paleozoic marine sedimentary manganese deposit. It is considered that the subduction and closure of Proto-Tethys ocean in Early Paleozoic is the main reason for the mineralization of Santonggou manganese deposit, and the metallogenic age of Santonggou manganese deposit is basically consistent with the closure time of Proto-Tethys ocean. [ABSTRACT FROM AUTHOR]

The Singhbhum Shear Zone in eastern India hosts several Fe oxide–Cu–Au (IOCG)-type polymetallic deposits, mined primarily for U, Cu and apatite, with elevated concentrations of rare earth elements, Ni, Co, Mo, Te and Au in association with low-Ti magnetite. Although the main stages of hydrothermal U, Cu and rare earth element mineralization are known to be Palaeoproterozoic in age, the age of shear deformation in the host shear zone has hitherto not been constrained. Here, we report Re–Os ages of syn-shearing massive molybdenite occurring along shear surfaces transecting the uranium ores in the Jaduguda uranium deposit. Integrating the obtained Re–Os age of c. 1.64–1.59 Ga of molybdenite, the known ages of mineralization and the known tectonothermal events in the adjoining Proterozoic Mobile Belt, we propose that the main stages of polymetallic hydrothermal mineralization pre-dated the pervasive shear deformation event in the Singhbhum Shear Zone. We further suggest that the shear zone was not the principal foci of the hydrothermal mineralization of the main stages. Instead, the shear zone was localized during the Palaeoproterozoic to Mesoproterozoic transition (c. 1.64–1.59 Ga) along pre-existing crustal-scale extensional faults which had earlier been the foci of hydrothermal alteration and mineralization in Palaeoproterozoic time (c. 1.9–1.8 Ga). Shear deformation and metamorphism have reconstituted/redistributed existing mineral/metal inventories with/without neo-mineralization. [ABSTRACT FROM AUTHOR]

The giant Shilu Fe-Cu-Co deposit in Hainan Island, South China, which was structurally and hydrothermally superimposed, is mainly hosted in highly metasomatized dolostones/marbles of the ~ 900 Ma Shilu Group. This study confirmed that the ore bodies are originally strata-bound and epigenetic, but do not have spatial relations with any coeval intrusions. In this study, the paragenetic sequence of the pre-deformation mineralization is refined and consists of early Ca-silicate alteration (I), Fe (II), and Cu-Co (III) mineralization stages, followed by multiple overprints and/or undeformed veins (stage IV). Our new oxygen and in situ Pb–S isotopic results for stages I to III show that the mineralizing fluids were initially magmatic-hydrothermal but have undergone variable degrees of interaction with country rocks during mineralization. On the other hand, stage IV fluids have in situ Pb–S isotopic compositions indicative of significant contributions of early-stage components through secondary re-mobilization. These features, in combination with chemical compositions of Fe oxides (e.g., elevated Ti in hematite), strongly argue that the Shilu deposit does not belong to BIF as previously considered, but is typical of magmatic-hydrothermal IOCG deposits. New sulfide Re-Os isotopic data show that the major Fe-Cu-Co mineralization formed at 780 ± 24 Ma (MSWD = 0.62). The deposit is confirmed to be broadly comparable to Neoproterozoic IOCG deposits in the Ailao Shan-Red River shear zone in terms of timing and nature of mineralization. Given that the shear zone likely extends to Hainan Island, the Shilu deposit is considered to be part of the same IOCG metallogenic belt and similar mineralization along the shear zone may be more widespread than previously thought. [ABSTRACT FROM AUTHOR]

The Tuwu–Yandong belt contains five porphyry Cu deposits (Fuxing, Yandong, Tuwu, Linglong, and Chihu), constituting the largest Cu metallogenic belt in Northwest China. However, the metallogenic framework for porphyry Cu deposits in the belt remains controversial. Rhenium-osmium dating of molybdenite from the Tuwu, Linglong, and Chihu deposits and comparisons with previous geochronological data of five deposits suggest that two episodes (335–330 Ma and 323–315 Ma) of porphyry Cu–Mo mineralization occurred in the Tuwu–Yandong belt, and the metals were mainly sourced from the mantle. Moreover, combined with the geodynamic framework of this belt, the compressional environment may be more favorable for porphyry Cu mineralization, and further exploration into the Early Carboniferous porphyry Cu deposits in this belt is expected. [ABSTRACT FROM AUTHOR]

The rhenium-osmium (Re-Os) geochronometer is newly developed technology and has been regarded as a promising radiometric tool for the direct dating of the deposition of source rock, hydrocarbon generation, migration and consequent alteration (e.g., thermal cracking, thermochemical sulphate reduction), and oil-source correlation. However, the complex nature of Re-Os systems in organi-rich samples, including their relatively low elemental contents, multiple origins and occurrences, ambiguous homogenization mechanisms of 187Os/188Os and our limited understanding of the closed system of Re-Os systematics etc., often result in the relatively large uncertainties of obtained isochrones. In this paper, to improve their data quality and yield ideal Re-Os isochrons, the existing Re-Os isotopic analysis method was improved by the terms of sample selection and screening, chemical pretreatment, total analytical blank control and international reference material monitoring. Results showed that a comprehensive guide to researching working in Re-Os geochronology for petroleum system analysis can be available.

Re–Os geochronometer has been used in the dating of generation-accumulation, thermal cracking, and thermochemical sulfate reduction of crude oil and the oil-source correlation of petroleum systems in recent years. Re and Os concentrations are higher in the asphaltene fraction of crude oil and the earlier precipitated fractions of asphaltene. The correlations of the Re–Os isotopic systematics between asphaltene and maltene and among the fractions of asphaltenes are complex. It is shown by experiments that Re and Os can transfer from water to oil rapidly in a significant amount. However, Re–Os dating with multiple crude oil samples is suffering from great uncertainties while single oil dating methodology does not always work. A bright future for the application of Re–Os geochronometer on the dating of crude oil generation and accumulation requests further research on the homogenization mechanism of 187Os/188Os, the closed system of Re–Os systematics, and how Re and Os reside in crude oil.

The Kivilompolo molybdenite occurrence is located in the northern part of the Peräpohja belt, within the lithodemic Ylitornio nappe complex. It is hosted within a deformed porphyritic granite belonging to the pre-orogenic 1.99 Ga Kierovaara suite. The mineralization occurs mostly as coarse-grained molybdenite flakes in boudinaged quartz veins, with minor chalcopyrite, pyrite, magnetite, and ilmenite. In this study, we report new geochemical data from the host-rock granite and Re-Os dating results of molybdenite from the mineralization. For the whole-rock geochemistry, the mineralized granite is similar to the Kierovaara suite granites analyzed in previous studies. Also, the ca. 2.0 Ga Re-Os age for molybdenite is equal, within error, to the U-Pb zircon age of the Kierovaara suite granite. In addition, similar molybdenite and uraninite ages have been reported from the Rompas-Rajapalot Au-Co occurrence located 30 km NE of Kivilompolo. We propose that the magmatism at around 2.0 Ga ago initiated the hydrothermal circulation that was responsible for the formation of the molybdenite mineralization at Kivilompolo and the primary uranium mineralization associated with the Rompas-Rajapalot Au-Co occurrence or at least, the magmas provided heating, and in addition potentially saline magmatic fluids and metals from a large, cooling magmatic-hydrothermal system.

The Helukou deposit, with proven reserves of 33 752 t WO3, is one of the newly exploited mediumscale tungsten (W) deposits in the Guposhan ore field, Nanling Range of South China. Skarn-type and less abundant altered granite-type tungsten orebodies were identified in this deposit. The ore mineralization in this district was a product of two-stage magmatism, as shown by LA-ICP-MS U-Pb dating of zircons and Re-Os dating of molybdenite. The former yielded U-Pb ages of 184.0 ± 3.6 Ma (MSWD = 0.15) and 163.8 ± 1.5 Ma (MSWD = 0.41) for fine-grained biotite granite and muscovite granite, respectively, as well as a U-Pb age of 181.5 ± 2.1 Ma (MSWD = 0.75) for zircon grains from altered granite-type tungsten ore. The latter yielded molybdenite Re-Os ages of 183.5 ± 2.8 Ma (without MSWD owing to a limited number of samples) and 163.4 ± 2.8 Ma (MSWD = 0.71) for altered granite-type and skarn-type tungsten deposits, respectively. Thus, two separate tungsten mineralization events occurred during the Early Jurassic and Middle Jurassic. Trace-element compositions suggest that scheelite I was controlled by the coupled substitution reactions of 2Ca2+ = Na+ + REE3+ and Ca2+ + W6+ = Nb5+ + REE3+, whereas scheelite II was controlled by the coupled reactions of 2Ca2+ = Na+ + REE3+ and 3Ca2+ = Ca + 2REE3+ (where  is a site vacancy). High Mo and low Ce contents suggest that both scheelite I and scheelite II were precipitated from oxidizing magmatic-hydrothermal fluids. Based on the mineral assemblage of the altered granite-type ores and geochemical characteristics of scheelite I [i.e., negative Eu anomalies (0.02-0.05; mean = 0.03 and STD = 0.01), and high 87Sr/86Sr ratios (0.70939-0.71932; mean = 0.71345 and STD = 0.00245)], we infer that fluid-rock interaction played an important role in modifying Early Jurassic ore-forming fluids. Scheelite II exhibits a geochemical composition [i.e., 87Sr/86Sr ratios (0.70277-0.71471; mean = 0.70940 and STD = 0.00190), Eu anomalies (0.14-0.55; mean = 0.26 and STD = 0.09), and Y/Ho ratios (16.1-33.7; mean = 27.9 and STD = 2.91)] similar to that of the Middle Jurassic Guposhan granites, suggesting inheritance of these features from granite-related magmatic-hydrothermal fluids. These results provide new insights into the two-stage magmatic and metallogenic history of the Nanling Range during the Jurassic Period. [ABSTRACT FROM AUTHOR]

The Tuwu–Yandong belt contains five porphyry Cu deposits (Fuxing, Yandong, Tuwu, Linglong, and Chihu), constituting the largest Cu metallogenic belt in Northwest China. However, the metallogenic framework for porphyry Cu deposits in the belt remains controversial. Rhenium-osmium dating of molybdenite from the Tuwu, Linglong, and Chihu deposits and comparisons with previous geochronological data of five deposits suggest that two episodes (335–330 Ma and 323–315 Ma) of porphyry Cu–Mo mineralization occurred in the Tuwu–Yandong belt, and the metals were mainly sourced from the mantle. Moreover, combined with the geodynamic framework of this belt, the compressional environment may be more favorable for porphyry Cu mineralization, and further exploration into the Early Carboniferous porphyry Cu deposits in this belt is expected.

The newly discovered large-scale skarn deposit of Youmapo tungsten-molybdenum deposit is located in the Bobai-Cenxi metallogenic belt of the southeastern Guangxi, south China. The stratiform, lentoid, and vein ore-bodies occur along the contact zone between the Devonian calcareous-argillaceous siltstone and Youmapo granitic complex pluton. The Youmapo granitic complex pluton consists of main granodiorite (109.7 ± 1.1 Ma) and complementary muscovite granite (100.7 ± 0.5 Ma). Up to now, WO3 reserves were estimated at more than 80 thousand tons, with grades 0.191~1.284% WO3 and 0.001~0.019% Mo. Among them, No. I ore-body accounts for 84% of the total reserve. Four types of fluid inclusions are recorded in the Youmapo deposit (NaCl-H2O, NaCl-CO2-H2O, pure CO2, and monophase H2O) and characterized by medium-high temperature (190~340 °C) and low salinity (3~10 wt%NaCleq). According to the S, H, and O isotopic characteristics, the ore-forming fluid is mainly post-magmatic fluid. The complementary muscovite granite geochemically represents high evolution granite that derived the ore-forming fluid. Six molybdenite samples from No. I ore-body yield an 187Re-187Os isochron age of 100.1 ± 3.3 Ma and a consistent weighted average model age of 100.37 ± 0.62 Ma, suggesting the Cretaceous period for the tungsten-molybdenum mineralization and their spatio-temporal relation to the muscovite granite. [ABSTRACT FROM AUTHOR]

The H2SO4–CrO3 method has been widely used in Re‐Os isotope dating of organic‐rich sedimentary rocks. However, the high Re blank of this method inhibits the collection of high‐precision Re‐Os data, especially for organic‐rich sedimentary rocks with low Re and Os mass fractions. Here, we report a new H2SO4–Na2CrO4 method in which the Re blank of the Na2CrO4 reagent can be greatly reduced after efficient purification by acetone. A proportion of 0.6 g Na2CrO4/8 ml H2SO4 was selected as the best digestion combination based on tests of black shales with different organic carbon contents in three digestion media (inverse aqua regia, H2SO4–CrO3, and H2SO4–Na2CrO4). The H2SO4–Na2CrO4 method has an ultra‐low total procedural blank of 1–2 pg for Re and 0.6–1 pg for Os, respectively, which is one order of magnitude lower than the H2SO4–CrO3 method and is comparable with to inverse aqua regia method. The new method was applied to reference material SBC‐1 and two series of black shale samples, and the results were consistent with those obtained via the inverse aqua regia method. These findings confirm the accuracy and feasibility of the H2SO4–Na2CrO4 method, and demonstrate its ability to accurately determine the depositional age of organic‐rich sedimentary rocks with low Re and Os mass fractions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diverse W metallogeny of the Baiyunxian ore field intensively occurred in 156–153 Ma. • W metallogeny was associated with Late Jurassic highly evolved magmatic phases. • Metal element are derived from remelting of metasedimentary crustal basement. • Lithology of wall rocks is the major cause of varied W mineralization types. The Baiyunxian ore field, a large tungsten ore filed in the Nanling Metallogenic Belt of South China, hosts a variety of tungsten deposits such as the Dapu (quartz wolframite vein type), Chashanjiao (skarn type), Toutianmen (greisen type), and Dashan (quartz scheelite vein type). However, precise mineralization ages of these deposits remain poorly constrained and this has long vexed a better understanding of genetic relationships between diverse W mineralization types and the spatially associated Jiufeng granitic complexes. Here, we report firsthand zircon U–Pb, monazite U–Pb, garnet U–Pb, cassiterite U–Pb, and molybdenite Re–Os ages of different granites and ores from the Baiyunxian ore field. The Jiufeng granitic complexes consists of phase Ⅰ biotite granite (P1), phase Ⅱ two-mica granite (P2), and phase Ⅲ granitic dikes (P3, including greisen W ore). Zircons from P1 granite define a concordant U–Pb age of 166.0 ± 0.9 Ma (MSWD = 1.1). Monazites from P2 granite yielded a Tera–Wasserburg lower intercept age of 159.2 ± 0.7 Ma (MSWD = 0.45). In addition, zircons and monazites from P3 granite in the Toutianmen deposit yield a concordant U–Pb age of 154.7 ± 1.3 Ma (MSWD = 1.3) and a Tera–Wasserburg lower intercept age of 156.6 ± 1.9 Ma (MSWD = 0.14), respectively, suggestive of multi-stage emplacement processes of the Jiufeng complexes. Ten molybdenite samples from the Dapu deposit generate an isochron age of 156.0 ± 3.0 Ma (MSWD = 0.93). In situ garnet and cassiterite LA-ICP-MS U–Pb dating results of the Chashanjiao skarn deposit yield lower Tera–Wasserburg intercept ages of 155.3 ± 1.2 Ma (MSWD = 1.6) and 153.4 ± 3.7 Ma (MSWD = 1.3), respectively. These dating results indicate that different W mineralization events in the Baiyunxian ore field intensively occurred in the Late Jurassic (∼159–153 Ma). Despite a close spatial relationship between various W orebodies and P1 granite, the geochronological results demonstrate that extensive W metallogeny in the Baiyunxian ore filed likely occurred later than P1 granite and contemporaneous with P2–3 granites. In addition, scheelites from the four deposits have similar REE patterns that are characterized by weak MREE enrichment, despite few exceptions being found in scheelites from the Dashan and Chashanjiao deposits. This suggests that the diverse W metallogeny in the Baiyunxian ore field were derived from the same magmatic hydrothermal system and changed as the ore-forming fluid evolved. Multidisciplinary evidence indicates that the Late Jurassic highly evolved P2–3 granites of the Jiufeng complexes were crucial to W mineralization in the Baiyunxian ore field and the lithology of wall rocks exerted first-order control of W mineralization types. [ABSTRACT FROM AUTHOR]

The Nimbus Ag–Zn(–Au) deposit is a hybrid VHMS deposit with epithermal characteristics formed in the Eastern Goldfields Superterrane, Yilgarn Craton, under shallow water (~ 700 mbsl), low-temperature conditions. Intersections of some ore lenses are high-grade and polymetallic, making similar styles of mineralization attractive Yilgarn exploration targets. The mineralization at Nimbus is hosted by a bimodal felsic–mafic succession of volcanic rocks, which are overlain by a succession of least-altered polymict conglomerates with a carbonaceous to dacitic matrix. A new Re–Os age (2680 ± 34 Ma; nodular pyrite and black shale) suggests that the overlying polymict conglomerate is coeval to ~ 2.70 Ga volcanism and mineralization at Nimbus. The pyrite within the high-grade polymetallic sulfide assemblages has a consistently lower Sb/Ag ratio (1–30) than pyrite from other sulfide phases (e.g., 30 to 1000 in colloform and barren pyrite). Trace elements (TEs) in sedimentary nodular pyrite from multiple intervals along a single drillhole (NBDH010), indicate the existence of an enriched sedimentary interval with higher total TE content, Ag/Au and Sb/Au, lower S/Se, and polymetallic-like signature of Sb/Ag. Within this enriched interval, the black shale matrix of the polymict conglomerate shows higher total organic carbon (TOC), Mo content, and Co/Ni ratios and suggest increased bio-activity at that time, interpreted to be associated with the Ag–Zn(–Au) mineralization. The TE characteristics in sedimentary pyrite, reflecting increased metal content in seawater inferred from in situ pyrite trace element analysis has the potential to be developed into an exploration tool for successions, adjacent and coeval to similar ore deposits. [ABSTRACT FROM AUTHOR]

Re–Os radiometric dating of crude oil can be used to constrain the timing of hydrocarbon generation, migration or charge. This approach has been successfully applied to marine petroleum systems; however, this study reports on its application to lacustrine-sourced natural crude oils. Oil samples from multiple wells producing from the Cretaceous Nantun Formation in the Wuerxun-Beier depression of the Hailar Basin in NE China were analysed. Subsets of the Re–Os data are compatible with a Cretaceous hydrocarbon generation event (131.1 ± 8.4 Ma) occurring within 10 Myr of deposition of the Nantun Formation source rocks. In addition, two younger age trends of 54 ± 12 Ma and 1.28 ± 0.69 Ma can be regressed from the Re–Os data, which may reflect the timing of subsequent hydrocarbon generation events. The Re–Os geochronometer, when combined with complementary age dating techniques, can provide direct temporal constraints on the evolution of petroleum system in a terrestrial basin. [ABSTRACT FROM AUTHOR]

The Bondar Hanza porphyry Cu deposit, hosted by a granitoid stock, is located 120 km south of Kerman city in the elongated NW–SE trending Urumieh‐Dokhtar magmatic arc (UDMA), Iran. The granitoid stock is a multiphase intrusive body, 2 km2 in surface area, which comprises microdiorite–microquartz diorite and granite–granodiorite. Petrological and geochemical analyses show that granitoids are peraluminous, magnesian, calcic to alkali‐calcic, and non‐adakitic intrusions characterized by negative Eu* anomalies. Thermobarometric and oxygen fugacity calculations indicate that magma emplacement occurred at 719–784°C, <100 MPa, and at a log fO2 of NNO +1.6 to +3.2. Sulphur isotopic composition of sulphide minerals (δ34S = 5.0–6.8 ‰) are similar to other porphyry Cu deposits worldwide. Molybdenite separates yield Re–Os ages of 28.22–28.03 Ma, indicating that the Cu mineralization and associated magmatism occurred during the Oligocene. The Bondar Hanza is one of the several granitoids from small porphyry Cu deposits in the UDMA that is related to island arc sub‐productive granitoids. It seems that the largest ore‐hosting porphyry systems within the UDMA are generally restricted to Miocene intrusions with adakitic affinity (e.g., Sarcheshmeh granitoids) and that the temporally discrete non‐adakitic magmatic systems are sub‐productive to barren. These data are interpreted to show that magmatism in the Bondar Hanza region was likely associated with partial melting of juvenile lower crust induced by north‐eastward subduction of the Neo‐Tethys oceanic lithosphere. [ABSTRACT FROM AUTHOR]

The Baishan Mo deposit in the eastern Tianshan Mountains is representative of the local metallogenic Triassic Mo belt. In this study, the geological characteristics, petrography, and geochemistry of the granite porphyry and the Mo deposit were examined using zircon U–Pb dating, molybdenite Re–Os isotope dating, whole‐rock geochemistry, and fluid inclusions. Results show that the crystallisation age of the Baishan granite porphyry is 229.8 ± 1.4 Ma and the Re–Os age of molybdenite in the ore body quartz vein is 225.0 ± 1.2 Ma. Therefore, the ore formed basically at the same time as diagenesis in the Late Triassic. The Baishan granite porphyry has high levels of Si, Al, and alkalis (K2O + Na2O = 5.72–8.88%) and low levels of Mg. The differentiation index is high (81.68–91.20), while the aluminium saturation index is low, indicating that the pluton belongs to metaluminous–weak peraluminous highly fractionated I‐type granite. The rock is also enriched in light rare earth elements (LREE) and large‐ion lithophile elements but depleted in heavy rare earth elements (HREE) and high‐field‐strength elements, with a distinct differentiation between LREEs and HREEs. δEu is weakly negative. The high Sr/Y and La/Yb ratios indicate geochemical characteristics similar to adakite rocks. The formation of the deposit is closely related to Mo‐rich, low‐salinity (1.23‐ to 9.73‐wt.% NaCl eqv.), and medium‐ to low‐temperature (91–280°C) magmatic fluid in the plate extension setting. The magma was derived from partial melting of thickened lower crust and possibly mixed with intrusive mantle‐derived magma. The ore‐forming fluids were uplifted, transported, mixed with meteoric water, and precipitated to form the Mo ore. [ABSTRACT FROM AUTHOR]

Geological characteristics, trace element geochemistry, and Re–Os dating of molybdenite are presented and discussed for seven Cu and Mo porphyry, one Cu skarn-porphyry and two Mo and Mo–W greisen deposits. Re contents in molybdenite are discussed versus ore mineralogy, molybdenite polytypes, formation temperature, and whole rock chemistry of parental rocks. They are also evaluated in the light of the geotectonic settings of these deposits and tectonic history of the Urals. Re–Os dating of molybdenite evidences that the porphyry deposits studied are confined to four volcanic arc terranes of the Urals and are linked to four subduction events: Tomino and Birgilda (ca. 430 Ma) and Zeleny Dol (ca. 420 Ma) porphyry deposits linked to the East Uralian volcanic arc; Voznesenskoe porphyry (ca. 395 Ma) and Verkhneuralskoe porphyry (ca. 365 Ma) deposits linked to the Magnitogorsk arc and its collision to the East European continent respectively; Mikheevskoe porphyry and Tarutino skarn-porphyry deposits (ca. 360 Ma) linked to subduction under the East Uralian microcontinent; Benkala porphyry deposit (ca. 335 Ma) linked to the activity of the Valerianovka Andean-type arc. The Talitsa Mo porphyry deposit (ca. 300 Ma) as well as Yuzhno-Shameiskoe (ca. 280 Ma) and Koklanovskoe (ca. 255 Ma) greisen Mo–W deposits are linked to collision between East European and Kazakh continents. Electron microprobe analysis and laser ablation inductively coupled mass-spectrometry of molybdenite demonstrate an extremely irregular distribution of all trace elements on both grain-scale and deposit-scale levels. Most trace elements (Fe, Co, Cu, Zn, As, Se, Ag, Sb, Te, Pb, Bi, etc.) form mineral inclusions within molybdenite while Re and W are commonly incorporated into molybdenite lattice. Re contents and distribution in molybdenite are indicative for tectonic setting of the deposits. Molybdenite from deposits formed within intra-oceanic arcs (Mikheevskoe, Tomino, and Voznesenskoe porphyry Cu deposits) is featured by high Re contents (1000–5000 ppm) and low W contents (<10 ppm). Molybdenite from Verkhneuralskoe (arc-continent collision stage) and Benkala (Andean-type arc) deposits is featured by lower Re contents (mainly 400–900 ppm) and higher W contents (30–120 ppm). Molybdenite from Talitsa Mo-porphyry, and Yuzhno-Shameiskoe and Koklanovskoe greisen deposits (continent-continent collision) is featured by the lowest Re contents (<10 ppm to 370 ppm) and the highest W contents (10 to 150 ppm). Geometrical mean Re content in molybdenite for all ten deposits studied has positive correlation with average Cu/Mo ratio in ore implying mass balance was one of the key controls of Re incorporation in molybdenite. In addition, Re content has a negative correlation with SiO 2 and total REE contents in ore-bearing intrusive rocks as well as with the absolute age of the deposits which correlates with the general evolution of porphyry- and greisen-type deposits of the Urals. For subduction-related porphyry deposits magma composition was generated with strong influence of the shallow subduction component. Fluid-mobile elements and various degrees of partial melting of the mantle wedge strongly depend on Re contents. Collision tectonic settings are marked by low Re concentrations in molybdenite. [ABSTRACT FROM AUTHOR]

The Siah Kamar porphyry Mo deposit is the newly discovered deposit of this type in the Neo Tethys-related Urumieh–Dokhtar magmatic arc, northwest Iran. Mineralization occurs as stock-work quartz–molybdenite and mono-mineralic molybdenite veinlets within the porphyry quartz-monzonite stock and the country rocks, accompanied by locally scattered later-stage and cross-cutting quartz-chalcopyrite-pyrite veinlets in the trachy-andesite and trachy-basalt country rocks. U–Pb zircon geochronology of the porphyry stock yielded Early Oligocene dates of 32.7 ± 0.4 to 30.9 ± 0.4 Ma (at 2σ level). The Th/U ratios of the zircons range between 0.48 and 0.77, and they possess initial εHf(t) values of 3.2 to 12.1, which may suggest a dominant mantle source for the magma. Molybdenite separates yielded rhenium contents between ~10 and 41 ppm (average ~26 ppm, n = 4) and slightly younger Re–Os ages compared to the porphyry stock, ranging from 29.1 ± 0.2 to 28.1 ± 0.2 Ma (at 2σ level). The Siah Kamar porphyry Mo deposit is nearly temporally coeval with the Haft Cheshmeh porphyry Cu deposit and the vein-type Cu–Mo–Au mineralization in the Qarachilar area, corresponding to the second porphyry Cu–Mo mineralization epoch in NW Iran. However, it is younger than the majority of the porphyry Cu deposits in the southern Lesser Caucasus and only shows temporal correlation with the Paragachay and first-stage Kadjaran porphyry Cu deposits. Moreover, it is older than all the porphyry Cu–Mo systems across the central and south-eastern parts of the Urumieh–Dokhtar magmatic arc, except the Bondar Hanza deposit, which is nearly coeval with the Siah Kamar porphyry Mo deposit. All these data reveal an old to young trend along the UDMA and the porphyry Cu belt of Iran, further testifying to the diachronous and later closure of the Neo-Tethyan oceanic basin in central and SE Iran. [ABSTRACT FROM AUTHOR]

In this study, the USGS black shale reference material SBC‐1 was investigated as a matrix‐matched reference material for both intra‐laboratory calibration and inter‐laboratory comparison of high‐precision Re‐Os dating for organic‐rich sedimentary rocks. This reference material was analysed for Re‐Os isotopic composition by three digestion protocols – inverse aqua regia, CrO3‐H2SO4 and H2O2‐HNO3. The results for SBC‐1 obtained by inverse aqua regia digestion yielded similar Re mass fractions but slightly (~ 5%) higher Os mass fractions and lower 187Os/188Os values than the CrO3‐H2SO4 and H2O2‐HNO3 digestions. The data set of inverse aqua regia digestion exhibited strong correlations in plots of 187Os/188Os vs. 1/192Os and 187Os/188Os vs. 187Re/188Os, which may signify the incorporation of detrital Re and Os into organic matter in the Re‐Os system. Similar correlations were also observed for the CrO3‐H2SO4 digestion data set, but not for that of H2O2‐HNO3. The data indicate that there is an amount of non‐hydrogenous Os in SBC‐1 and that CrO3‐H2SO4 and H2O2‐HNO3 digestions would minimise liberation of the non‐hydrogenous Os component. We propose that SBC‐1 may be a more suitable reference material to monitor the influence of detrital Re and Os on Re‐Os isochron age data, especially for samples with less organic matter and more siliceous detritus. [ABSTRACT FROM AUTHOR]

The Aksug porphyry Cu-Mo deposit is located in a region of long-lasting magmatic activity. Gabbroids of the Khoito-Oka complex are the earliest intrusive rocks, in which the Aksug granitoid pluton hosting ore-bearing small porphyry intrusions is localized. The intrusive activity was terminated with emplacement of late leucogranite dikes. There are different viewpoints on the age of magmatism and mineralization of the Aksug deposit, with the concept of their Devonian age prevailing. To solve the debatable issue, we performed isotope geochronological studies and analyzed new results of U-Pb (SHRIMP-II) zircon dating and previously published Re-Os molybdenite dates (518 ± 2, 516 ± 2, and 511 ± 2 Ma). The concordant U-Pb zircon ages for igneous rocks are younger than the Re-Os age for mineralization. New U-Pb dating of Khoito-Oka gabbro-diorites has yielded an age of 503 ± 2 Ma. The U-Pb SHRIMP zircon age of tonalites from the Aksug pluton has been estimated at 504 ± 5 Ma. The U-Pb zircon ages for ore-related tonalite porphyry I and tonalite porphyry II are 500 ± 6 and 499 ± 6 Ma, respectively. The obtained SHRIMP age for leucogranite dike is 509 ± 4 Ma. Two groups of U-Pb dates have been obtained for each of the analyzed zircon samples: close to the Re-Os dates (518-511 ± 2 Ma) and younger (507-486 Ma). The weighted average zircon ages calculated for early and late populations from post-ore leucogranites are 515 ± 4 and 500 ± 4 Ma, respectively. We suggest that zircons with an age close to the Re-Os dates found in post-ore leucogranites were assimilated from the underlying substrate and zircons with an age of 500 ± 4 Ma crystallized from melt. The oldest U-Pb dates (509-515 Ma) of individual zircon grains from ore-bearing tonalite porphyry are consistent with the Re-Os molybdenite ages. Zircons from tonalite, tonalite porphyry, and Khoito-Oka gabbroids sometimes show internal textures indicating secondary alteration. The younger U-Pb concordia zircon ages relative to the Re-Os dates might be due to the influence of late thermal processes on the U-Pb isotopic system. The younger dates (486-507 Ma) of individual zircon grains probably reflect the time of the impact of a thermal fluid process. The weighted average of these younger dates (502 ± 2 Ma) falls within the weighted average age of post-ore leucogranites (500 ± 4 Ma). According to the Re-Os dates, the Aksug deposit formed at the end of the early Cambrian. Ore occurrences similar in magmatism and mineralization to the Aksug ore deposit are widespread in Tuva and in the Lake Zone in Mongolia. Therefore, it is necessary to reassess the role of the Cambrian and Devonian magmatism in the development of porphyry Cu-Mo mineralization both in Tuva and in the Altai-Sayan orogenic area. [ABSTRACT FROM AUTHOR]

Abstract It was previously proposed that the onset of east–west extension in the Himalayan orogen occurred after ca. 19 Ma. Here we present a Re–Os isochron age of ca. 43 Ma for sulfides from the Zhaxikang Zn–Pb–Sb–Ag polymetallic deposits, which occur within N–S–striking normal faults that reflect E–W extension in the Tethyan Himalayan orogen. This age is consistent with previously reported ages for regional metamorphism (ca. 48–42 Ma), granitoids (ca. 47–40 Ma) and gabbros (ca. 45 Ma) occurring along the Indus–Yarlung suture. In addition, this type of structure also broadly occurs in the Lhasa terrane, and plays a critical role in the Eocene porphyry–(skarn) copper polymetallic mineralization there. By ca. 45–43 Ma, the north–south–directed horizontal deviatoric stresses had peaked and subducted Neo–Tethyan slab breakoff had occurred at great depth, leading to abrupt slowdown of Indo–Asia convergence (ca. 45 Ma). E–W extension initially developed at shallow depths, resulting in formation of the north–south trending normal faults in the plateau. This type of extension would lead to collapse of the Tibetan plateau and decrease in altitude, subsequently resulted in Central Asian and the global climate changes. Our study places new constraints on the timing and nature of early Cenozoic tectonics and metallogenesis in the Himalayan orogen and climate changes in Central Asia. Graphical abstract Image 1 Highlights • E-W extension initially occurred in the Eocene (ca. 43 Ma). • E-W extension was coeval with N-S compression in SE Tibet. • E-W extension pays a critical role in regional tectonics and metallogenesis and Asian climate changes. [ABSTRACT FROM AUTHOR]

In the Precambrian dolomites in the central Sichuan Basin, a substantial paleo-oil system previously existed, which has since evolved into a dry gas system that is currently in place. The genesis of this paleo-oil system remained poorly understood, leaving uncertainties regarding the timing of oil charging and associated source rocks. Integration of Re–Os geochronometry with basin modeling allows temporal-spatial constraints on the ancient petroleum system to be established. Two texturally distinct generations of reservoir bitumen were identified. Late-generation bitumen yielded a geologically meaningful Re–Os age of 189 ± 20 Ma (MSWD = 10.4, 2σ), distinct from the previously documented Re–Os ages such as the 414 ± 44 Ma reported by Shi et al. (2020). This new age, along with the ∼414 Ma, aligns within uncertainties with the two relative timings derived from our independent basin model (ca. 450–390 Ma and 260–180 Ma), revealing two temporally distinct oil generation-migration events. The date of ∼189 Ma also lends support to the previous oil charge timing inferred from fluid inclusions. We evaluated the imprecisions of these two Re–Os ages and considered them to result from a narrow spread in 187Re/188Os, and variations in initial Os isotopic compositions (Os i) due to the giant size of the petroleum system and a long duration of oil generation from source kitchen over a large geographical area in this play. Effects of asphaltene precipitation, due to uplift-induced decompression of the migrating oils, may also have contributed to the scatter. Separating the samples based on Os i produced a higher precision age (184.1 ± 5.7 Ma, Model 1) with an MSWD of 0.97. The first oil charge is relatively weak as shown by the basin model and observed bitumen volumes, and it had not been well preserved due to significant reservoir exhumation by Caledonian tectonism. Consequently, the younger oil charge is considered to be the principal precursor to the current dry gas accumulations. Os isotope histories for four potential source units were constructed using publicly available Re–Os data. Comparisons between bitumen and rock Os compositions tend to support the lower Cambrian Qiongzhusi Formation as the predominant source unit for the two major paleo-oil charges. However, contributions from the Duoshantuo, Dengying, and Maidiping source rocks can not be precluded. Overall, these new observations allow temporal-spatial constraints to be placed on the complex evolution, from paleo-oil generation to destruction and dry gas generation. • Two paleo oil charges sourced from the lower Cambrian Qiongzhusi shales. • Agreement between two bitumen Re–Os ages and modeled oil generation stages. • Assessing the precision limitations of hydrocarbon Re–Os ages. [ABSTRACT FROM AUTHOR]

Re-Os isotope method is a powerful tool for dating ore deposits, but digesting samples with the Carius tube is complicated and dangerous.A simple and quick method to determine the age of molybdenite Re-Os and Re content has been established.5-15 mg of molybdenite samples were digested with 3 mL HNO3 in a 10 mL colorimetric cylinder.Molybdic acid in solution was removed by a centrifuge, the supernatant of the solution was then diluted to an appropriate volume.M187/M185 ratio of the resulting solution was determined directly by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS).According to the principle of radioactive decay, it can be inferred that the mass ratio is positively correlated with the age.The Re-Os age of the sample can be calculated by comparing with the M187/M185 ratio of the molybdenite standard material(JDC and HLP).The Re content in the sample can be calculated on the basis of 185Re counting using the relative method.In order to test the reliability of this method, a series of molybdenite samples, whose ages vary from 13.26 Ma to 2130 Ma, were analyzed.The resulting ages were generally identical to the reference ages within 0.36%-7.42% deviations.The samples with older ages yield better results because the 187Os is more radiogenic.This method, without spike addition, can avoid the trouble of sealing and opening the Carius tube and the process of separating and purifying Re and Os, which significantly improves the experimental efficiency.This simple and quick method is highly suitable for the preliminary analysis of molybdenite Re-Os ageing.

The quartz-vein-type Baiyinhan tungsten deposit is located at the eastern part of the Central Asian Orogenic Belt, NE China. Analyses of fluid inclusions, H-O isotope of quartz and Re-Os isotope of molybdenite were carried out. Three stages of mineralization were identified: The early quartz + wolframite + bismuth stage, the middle quartz + molybdenite stage and the late calcite + fluorite stage. Quartz veins formed in the three stages were selected for the fluid inclusion analysis. The petrographic observation and fluid inclusion microthermometry results revealed three types of fluid inclusions: CO2-H2O (C-type), liquid-rich (L-type) and vapor-rich (V-type). The homogenization temperatures of C-type, V-type and L-type inclusions were 233–374 °C, 210–312 °C, and 196–311 °C, respectively. The salinity of the three types of inclusions was identical, varying in the range of 5–12 wt%. The H-O isotope analyses results showed that quartz had δ18OH2O and δDSMOW compositions of −2.6‰ to 4.3‰ and −97‰ to −82‰, respectively, indicating that the ore-forming fluids were mainly derived from magmatic water with a minor contribution of meteoric water. The addition of meteoric water reduces the temperature and salinity of the ore-forming fluids, which leads to a decrease of the solubility of tungsten and molybdenum in the fluids and eventually the precipitation of minerals. Re-Os isotopic analysis of five molybdenite samples yielded an isochron age of 139.6 ± 7.6 Ma (2σ) with an initial 187Os of −0.05 ± 0.57 (MSWD = 3.5). Rhenium concentrations of the molybdenite samples were between 3.1 ug/g and 8.5 ug/g. The results suggest that the metals of the Baiyinhan deposit have a crust origin, and the mineralization is one episode of the Early Cretaceous tungsten mineralization epoch which occurred at the eastern part of the Central Asian Orogenic Belt.

In an effort to contribute to the discussion concerning the age of rocks of the Moldanubian Variegated Group, we have undertaken Re-Os dating of molybdenite of banded carbonatite-like marbles (CLM) from the graphite mine Václav at Bližná (Southern Bohemia), which belong to the metamorphic sequence of this group. The Re-Os model ages for the molybdenites range between 493 and 497 Ma and apparently correspond to the early stages of metamorphism connected with pre-Variscan rift-related tectono-metamorphic events, which affected and recrystallized sedimentary CLM material rich in Mo-Th-Nb-REE. The molybdenite bearing carbonatite like marbles situated in the footwall of Bližná graphite mine have been interpreted as carbonates with a large share of volcano-detritic material derived from contemporaneous primitive alkaline (carbonatite-like) volcanism deposited in a shallow marine lagoonal environment. There is no geological evidence for the participation of fluids mobilized from host rocks in the formation of the CLM. Because the Re-Os chronometer in molybdenite is demonstrably stable through later Variscan facies metamorphism, the molybdenite chronometer has not been affected by subsequent thermal overprints associated with the Variscan orogeny.

Graphical abstract Highlights • The Qarachilar deposit is a vein-type Cu-Mo-Au mineralization related to Cu-Mo porphyries. • Fluid boiling and mixing facilitated hydrothermal alteration and mineralization. • Stable isotopes suggest the ore–fluid system evolved from magmatic to meteoric. • Mineralization at Qarachilar is related to collisional Eocene magmatic–hydrothermal activity. Abstract In the Qarachilar Cu-Mo-Au deposit of the Ahar–Arasbaran metallogenic zone (AAMZ), northwest Iran, mineralization occurs as three quartz-sulfide veins that cut granodiorite-quartz monzodiorite rocks of the Qaradagh batholith (QDB). Ore formation can be divided into three stages, with chalcopyrite, molybdenite, and gold-bearing pyrite appearing mainly in the first two stages. The main wall-rock alteration is silicification, and intermediate argillic, carbonate, and propylitic alteration. Fluid inclusion microthermometry indicates trapping of medium- to high-salinity (9.2–55 wt% NaCl equiv.) fluids at Qarachilar. Fluid inclusion trapping conditions are estimated to be 190 °C–530 °C and 0.1–3 kbar. The variable phase ratios as well as spatial coexisting of liquid- and vapor-rich two-phase and halite-bearing multiphase fluid inclusions homogenizing over the same temperatures are consistent with fluid boiling during ore formation. Obtained δ18O H2O values of quartz from ore-stage veins are +5.7‰ to +9.7‰, signifying that the ore–fluid system was predominantly magmatic water. The average calculated δ34S H2S values are 1 ± 1‰ for pyrite, chalcopyrite and molybdenite, consistent with a magmatic source for sulfur. Combined, the fluid inclusion and stable isotope data indicate that the ore-forming fluids at Qarachilar were magmatic in origin and were subsequently cooled and diluted by meteoric water. Fluid boiling and mixing facilitated hydrothermal alteration and mineralization. Molybdenite Re–Os dating shows that mineralization occurred at 42.35 ± 0.16 Ma, coincident with formation of porphyry Cu-Mo mineralization at Agarak deposit, and Hanqasar, Aygedzor and Dastakert prospects in the Lesser Caucasus. However, Qarachilar is older than all porphyry Cu-Mo mineralization in the AAMZ and Urumieh-Dokhtar magmatic arc (UDMA), which suggests that collision between Arabia and Eurasia were oblique and thus diachronous. Our data suggest that mineralization at Qarachilar is related to collisional Eocene magmatic–hydrothermal activity related to Neo-Tethys subduction, and shares a number of similarities with the vein-type Cu-Mo-Au mineralization related to Cu-Mo porphyries. [ABSTRACT FROM AUTHOR]

Atom probe microscopy (APM) is a relatively new in situ tool for measuring isotope fractions from nanoscale volumes (< 0.01 μm3). We calculate the theoretical detectable difference of an isotope ratio measurement result from APM using counting statistics of a hypothetical data set to be ± 4δ or 0.4% (2s). However, challenges associated with APM measurements (e.g., peak ranging, hydride formation and isobaric interferences), result in larger uncertainties if not properly accounted for. We evaluate these factors for Re‐Os isotope ratio measurements by comparing APM and negative thermal ionisation mass spectrometry (N‐TIMS) measurement results of pure Os, pure Re, and two synthetic Re‐Os‐bearing alloys from Schwander et al. (2015, Meteoritics and Planetary Science, 50, 893) [the original metal alloy (HSE) and alloys produced by heating HSE within silicate liquid (SYN)]. From this, we propose a current best practice for APM Re‐Os isotope ratio measurements. Using this refined approach, mean APM and N‐TIMS 187Os/189Os measurement results agree within 0.05% and 2s (pure Os), 0.6–2% and 2s (SYN) and 5–10% (HSE). The good agreement of N‐TIMS and APM 187Os/189Os measurements confirms that APM can extract robust isotope ratios. Therefore, this approach permits nanoscale isotope measurements of Os‐bearing alloys using the Re‐Os geochronometer that could not be measured by conventional measurement principles. [ABSTRACT FROM AUTHOR]

Sulphide inclusions are common features of natural diamonds. They can provide an insight into the nature of diamond-forming reactions and are especially important for Re–Os dating of diamond formation. A discrete molybdenite (MoS 2 ) phase has been identified for the first time by Raman spectroscopy in 73 out of 80 syngenetic sulphide inclusions in 7 eclogitic diamonds from the Mir kimberlite (Yakutia, Russia). The sulphide inclusions were chemically and texturally characterised by electron probe microanalyses (EPMA), focused ion-beam scanning electron microscopy (FIB-SEM) and synchrotron-based X-ray tomographic microscopy (SXRTM). Our observations suggest the molybdenite has unmixed from an original sulphide melt or monosulphide solid solution. It occurs as sub-micron sized grains, commonly in association with the chalcopyrite rims of the inclusions and sometimes, within surrounding decompression cracks. Molybdenite has also been identified by Raman spectroscopy in at least 50% of sulphide inclusions in preliminary studies of eclogitic diamonds from Argyle (NW Australia), Orapa, Letlhakane, Damtshaa (Botswana) and Dachine (French Guiana), and peridotitic diamond-hosted inclusions from Udachnaya (Yakutia, Russia) and Murowa (Zimbabwe). We have modelled the effects that different amounts of Re loss – through its segregation into an unrecovered molybdenite phase – could have on the radiometric ages of diamonds dated using the Re–Os system. In general Re loss through this process will lead to isochron ages older than the true age, and variable degrees of Re loss will lead to increased scatter around the apparent isochron. For model age calculations, the effects would depend on the 187 Re/ 188 Os ratio of the inclusions (if their compositions evolved above or below that of the chondritic mantle evolution curve) but Re loss could generate unrealistically old or future ages, particularly in eclogitic inclusions. [ABSTRACT FROM AUTHOR]

The Oligocene – Miocene Maikop Series is a world‐class source interval and is the most important source rock for the petroleum systems of the South Caspian Basin and surrounding region. The Maikop is a thick (up to 3 km) succession of silty mudstones with intervals of high organic carbon content. However correlation of organic‐rich intervals within the South Caspian Basin and beyond to basins of the Eastern Paratethys is problematic. Current age constraints are based primarily on microfaunal assemblages, but the assemblages are lacking in precision and are sparsely dispersed. This study provides a numerical age datum for Maikopian strata that may be used to improve correlation of organic‐rich intervals both locally and regionally. The age date obtained was produced via Re‐Os isotope geochronology. Of the five sample suites analyzed, one Re‐Os data‐set yielded an isochron of 17.2 ± 3.2 Ma. Re‐Os data sets that failed to produce statistically meaningful isochrons provide qualitative age constraints by comparing calculated initial 187Os/188Os ratios from these samples to187Os/188Os ratios in seawater through time. [ABSTRACT FROM AUTHOR]

The Xiaoyao tungsten polymetallic skarn deposit in the eastern Jiangnan Massif of Yangtze Block is located at the contact between a granodiorite pluton and Sinian–Cambrian limestone. The intrusions in the tungsten-rich district comprise the Xiaoyao and other granodiorite plutons and granite porphyry dikes. The age determinations by LA–ICP–MS U–Pb dating of zircons indicate that the granodiorite formed at 149.4 ± 1.1 Ma, whereas the granite porphyry was emplaced at 133.2 ± 0.7 Ma. Re–Os dating of molybdenite from the skarn orebodies yielded a weighted average age of 148.7 ± 2.3 Ma (n = 5). These ages indicate that the tungsten mineralization is temporally related to the granodiorite. The granodiorites are metaluminous (A/CNK = 0.86–0.98) and in the high-K calc-alkaline series. They contain hornblende and have a negative correlation between P 2 O 5 and SiO 2 , indicating that they are typical I-type intrusions. The granite porphyries exhibit high alkali contents (Na 2 O + K 2 O = 7.97–9.53%), elevated FeO T /(FeO T + MgO) ratios (0.83–0.94), high concentrations of Zr, Nb, Ce, and Y, and high Zr saturation temperatures (average of 812 °C); thus, they are geochemically similar to A-type intrusions. The initial 87 Sr/ 86 Sr and ε Nd (t) values range respectively from 0.7074 to 0.7083 and from − 7.9 to − 1.3 for the granodiorite, and from 0.7008 to 0.7083 and from − 6.3 to − 4.7 for the granite porphyry. In addition, two-stage Nd model ages (T 2DM ) of 1.0–1.6 Ga for the granodiorite and 1.3–1.4 Ga for the granite porphyry indicate that the Proterozoic crustal rocks of the Shangxi Group could have contributed to the Xiaoyao magmas. The rhenium contents of the molybdenite grains vary from 32 to 136 ppm, suggesting that the molybdenum was derived mainly from a mixture of mantle and crustal sources. Based on the new geochemical data and regional geological investigations, we propose that the Late Jurassic mineralization-related I-type granodiorite was derived from the Neoproterozoic Shangxi metamorphic rocks with some additional input of mantle material. The magmatism was triggered by asthenospheric upwelling induced by slab tearing during oblique subduction of the paleo-Pacific plate beneath the South China Block. [ABSTRACT FROM AUTHOR]

The recently discovered Dongbulage Mo-polymetallic deposit is located in the southern part of the Great Xing’an Range, northeast China. Mineralization is closely related to the emplacement of Middle−Late Jurassic granitoids. In order to understand the petrogenetic link between mineralization and host granitoids, this study presents new zircon U−Pb ages, bulk-rock geochemistry, and molybdenite Re−Os ages for the Dongbulage deposits. LA-ICP-MS zircon U−Pb dating of the monzogranite and syenogranite intrusions yielded two weighted mean 206Pb/238U ages: of 164 ± 2 Ma and 165 ± 3 Ma, respectively. The subvolcanic rocks (red porphyritic granite and rhyolite) yielded a time interval between 161 ± 2 and 162 ± 3 Ma. In addition, molybdenite from the Dongbulage deposit gave a Re−Os isochron age of 162.6 ± 1.5 Ma, which was interpreted as the age of the mineralization. The new geochronology has established the close temporal and genetic relationships between the mineralization event and the emplacement of the Middle−Late Jurassic granitoids. Bulk-rock geochemistry shows that the Dongbulage granitoids are characterized by high SiO2, K2O, and A/CNK [Al2O3/(CaO + Na2O + K2O)(molar ratio)] values, and low TiO2, CaO, and MgO values, indicating a metaluminous to peraluminous, high-K calc-alkaline affinity. The granitoids also featured enrichments of large ion lithophile elements and light rare earth elements (LREE), and a relative depletion of high field strength elements (HFSE), along with an increasing negative δEu anomaly. The high differentiation index (DI), ranging from 81.75 to 94.76, and obvious fractionation between LREE and HREE, indicate that the Dongbulage granitoids are highly fractionated, metaluminous−peraluminous, and high-K calc-alkaline I-type granites. Combined with the regional geology, the Dongbulage granitoids may have formed during post-orogenic extension that followed the Mongol−Okhotsk Ocean closure coeval with subduction of the paleo-Pacific plate.

The Liwu copper polymetallic deposits are located in the Jianglang Tectonic Dome in the southeastern Songpan-Ganzi Fold Belt. The deposits contain more than 0.8 million tonnes (Mt) of Cu, 0.5 Mt of Zn, 133 t of Ag and 1300 t of Co. However, the detailed geologic features, formation ages and metallogeny of these deposits remain poorly understood. Our new analyses indicate that the Liwu-type copper polymetallic deposits (LTCPD) are epigenetic hydrothermal deposits. The major copper polymetallic orebodies were emplaced in the Late Jurassic (ca. 151.1 ± 4.8 Ma), approximately 4–2.5 Myr later than the local granites (ca. 160.9 ± 1.0 Ma–159.3 ± 0.9 Ma). The ores show variable Pb isotopic compositions, with initial 206 Pb/ 204 Pb ratios of 18.048–18.420, 207 Pb/ 204 Pb ratios of 15.595–15.724, and 208 Pb/ 204 Pb ratios of 38.335–38.795, similar to those of local plutons but significantly lower than those of the ore-hosting rocks. The ore-associated tourmalines are dravitic and relatively homogeneous and exhibit similar δ 11 B values (between −15.47 ± 0.83 and −5.91 ± 0.67 ‰). These geological and Pb-B isotopic features suggest that the deposits at Liwu have a post-magmatic hydrothermal origin, similar to the stratiform skarn deposit. The major ore-forming source is dominantly related to the coeval upper crust-derived magmatism in the region. [ABSTRACT FROM AUTHOR]

The Peräpohja belt comprises a greenschist to amphibolite facies; multiply-folded supracrustal sequence of quartzites; mafic volcanics; carbonate rocks; black shales; mica schists and greywackes deposited from ca. 2.44 Ga to 1.92 Ga; during protracted rifting of the Archaean basement. Metamorphism and multiple folding of the basin fill occurred during the Svecofennian orogeny (1.92-1.80 Ga). The Rompas Au-U mineralization is hosted within deformed and metamorphosed calcsilicate veins in mafic volcanics. Textural evidence suggests that deposition and periods of uraninite re-mobilization were followed by localized hydrocarbon-bearing fluid flow which produced pyrobitumen crusts around grains of uraninite. Gold precipitated during the latest hydrothermal event at around 1.75 Ga. In situ U-Pb dating of uraninite by laser ablation inductively coupled mass spectroscopy (LA-ICP-MS), and Re-Os dating of molybdenite, indicate that primary hydrothermal uranium mineralization forms two age clusters; about 2.03-2.01 and 1.95-1.94 Ga. Resetting of the U-Pb system and precipitation of new generations of uraninite are associated with major deformation and metamorphic stages of the Svecofennian orogeny at 1.91-1.89 Ga, 1.85 Ga, and 1.80 Ga. Gold deposition was synchronous with the emplacement of the 1.75-1.78 Ga late/post-orogenic granitoids. The gold-producing hydrothermal event is also recorded by Re-Os dating of molybdenite from the gold-bearing Mg-metasomatized metasedimentary and metavolcanic units at the Palokas prospect; a few kilometres from Rompas. Results of this study confirm that some domains in the structure of uraninite may preserve the original crystallization age, despite an overprinting amphibolite facies metamorphic and other hydrothermal events. The study supports the utility of in situ U-Pb dating of uraninite and the ability of Re-Os dating to assist in sorting out different hydrothermal events in areas with complex tectonic; magmatic and metamorphic histories. [ABSTRACT FROM AUTHOR]

The Neo-Tethyan subduction in Iran is characterized by the Urumieh–Dokhtar magmatic arc (UDMA), formed by northeast-ward subduction of the oceanic crust beneath the central Iran. This belt coincides with the porphyry copper metallogenic belt that comprises several metallogenic zones, including Ahar–Jolfa in northwest Iran. The Ahar–Jolfa metallogenic zone encompasses two main batholiths of Qaradagh and Sheyvardagh and numerous intrusive bodies of Cenozoic, which have produced many base and precious metal deposits and prospects. The former is considered as continuation of the Meghri–Ordubad pluton in South Armenian Block (SAB), which also hosts porphyry copper deposits (PCDs). The Sungun PCD is the largest occurrence in northwest Iran. Rhenium-Osmium ages of Sungun molybdenites are early Miocene and range between 22.9 ± 0.2 and 21.7 ± 0.2 Ma. Comparison of the ages obtained here with published ages for mineralization across the region suggests the following sequence. The earliest porphyry Cu–Mo mineralization event in northwest Iran is represented by Saheb Divan PCD of late Eocene age, which is followed by the second epoch of middle Oligocene, including the Cu–Mo–Au mineralization at Qarachilar and the Haftcheshmeh PCD. Mineralization in Sungun, Masjed Daghi, Kighal and Niaz deposits corresponds to the third mineralization event in northwest Iran. The first epoch in northwest Iran postdates all Eocene mineralizations in SAB, while the second epoch is coeval with Paragachay and the first-stage of Kadjaran PCDs. Its third epoch is younger than all mineralizations in SAB, except the second stage in Kadjaran PCD. Finally, the Cu mineralization epochs in northwest Iran are older than nearly all PCDs and prospects in Central Iran (except the Bondar Hanza PCD), altogether revealing an old to young trend along the UDMA and the porphyry Cu belt towards southeast, resulted from diachronous, later closure of the Neo-Tethyan oceanic basin in central and SE Iran. [ABSTRACT FROM PUBLISHER]

The West Junggar Metallogenic Belt (WJMB) is located between the Tianshan fault system and the Ertix fault system in the western part of the Central Asian Metallogenic Domain (CAMD). The belt features widespread late Palaeozoic granitic plutons, strike-slip faults, and porphyry copper and orogenic gold deposits. We collected nine molybdenite samples from the Baogutu III–IV Cu–Mo deposit and the Suyunhe Mo–W deposit, and 12 granitoid samples from the Jiaman, Kangde, Kulumusu, Bieluagaxi, Hatu, Akbastau, Miaoergou, Baogutu, Karamay, and Hongshan plutons in the WJMB. Molybdenite Re–Os dating gives metallogenesis ages of 312.7 and 299.7 Ma for the Baogutu III–IV and Suyunhe deposits, respectively.40Ar/39Ar thermochronology yields biotite ages ranging from 326 to 302 Ma and K-feldspar ages from 297 to 264 Ma, indicating a regional medium-temperature cooling history in the WJMB during the late Carboniferous to middle Permian. By integrating these data with previous zircon U–Pb, amphibole40Ar/39Ar, and zircon and apatite fission-track ages, we reconstruct the whole thermal history of the WJMB, which includes late Palaeozoic intrusive magmatism, porphyry Cu and W–Mo mineralization, and late Mesozoic tectonic uplift and exhumation of the WJMB. The regional40Ar/39Ar cooling ages are consistent with the timing of regional sinistral strike-slip faulting, thereby indicating the tectonic significance of the cooling ages. We suggest that the biotite40Ar/39Ar ages represent the static cooling of the granitic plutons after emplacement, since the ages are consistent with the U–Pb ages of the plutons. Thereafter, the oldest K-feldspar40Ar/39Ar age may record the initiation of sinistral strike-slip movement on the Darabut, Mayile, and Baerluke faults. The regional faulting resulted in significant uplift of the WJMB during the early and middle Permian. [ABSTRACT FROM PUBLISHER]

The Xilamulun molybdenum polymetallic metallogenic belt in eastern Inner Mongolia forms one of the most important Mo metallogenic belts in northeastern China. The Dongshanwan porphyry Mo-W polymetallic deposit, in the northeastern part of the Xilamulun metallogenic belt, occurs along the periphery of a granite porphyry and consists of Mo-W-Ag sulfide and oxide disseminations and veinlets in hydrothermal assemblages. LA-ICP-MS zircon U-Pb dating of the Dongshanwan granite porphyry yields a crystallization age of 142.15±0.91 Ma, whereas molybdenite Re-Os isotopic dating model ages are of 139.9-141.5 Ma and an isochron age is of 140.5±3.2 Ma (MSWD=1.2). The age consistency indicates that the Dongshanwan deposit was a product of Early Cretaceous magmatism. The Dongshanwan granite porphyry is a high-alkali high-potassium intrusion and has high SiO (75.39 wt.%-76.15 wt.%), low Al2O3 (12 wt.%-13 wt.%), Ba, Ti, P, and Sr contents, with negative Eu anomalies. The Y/Nb ratios are comparable to those of average continental crust and island arc basalts, corresponding to type-A2 granites. Our geochemical data indicate that the granite porphyry emplaced in an Early Cretaceous post-orogenic extensional environment following Mongol-Okhotsk oceanic subduction and subsequent continental collision. [ABSTRACT FROM AUTHOR]

The Donggebi Mo deposit located in NW China is a newly discovered, large, stockwork-type Mo deposit with ore reserves of 441 Mt @ 0.115% Mo. Ore bodies occur along faults and fractures at the external contact zone of a concealed porphyritic granite and volcaniclastic rocks of Gandun Formation, spatially associated with a fine-grained granite. Mo-bearing veins are mainly assemblages of volatile-rich K-feldspar-quartz-oxide, K-feldspar-quartz, polymetallic sulfides and calcite-quartz. Zircon LA-ICP-MS U–Pb dating yielded concordant ages of 234.6 ± 2.7 Ma and 231.8 ± 2.4 Ma for the porphyritic granite and the fine-grained granite, respectively; molybdenite Re–Os dating gave an isochron age of 234.0 ± 2.0 Ma. These ages further confirm an important and extensive magmatic-metallogenic event in Eastern Tianshan during the Triassic Indosinian orogeny. Whole-rock major and trace element analyses indicate that the granitic rocks associated with Mo mineralization are high in Si, K, Rb, Th, Nb, Ta, Ga and LREE, but low in P, Ti, Sr and Ba, belonging to high-K calc-alkaline granites with A-type features. Magma was likely derived from the re-melting of thickened lower crust in a post-collision compression environment in the Late Permian, experienced strong crystal fractionation and formed the large Donggebi Mo deposit under an intra-plate extension setting in the Early to Middle Triassic. [ABSTRACT FROM AUTHOR]

The Haobugao Zn–Fe deposit is a typical skarn deposit located in the southern part of the Great Xing’an Range that hosts polymetallic mineralization over a large region. The main ore minerals at the deposit include sphalerite, magnetite, galena, chalcopyrite and pyrite, and the main gangue minerals include andradite, grossular garnet, hedenbergite, diopside, ilvaite, calcite and quartz. There are broadly two mineralizing periods represented by the relatively older skarn and younger quartz–sulfide veins. In detail, there are five metallogenic stages consisting of an early skarn, late skarn, oxide, early quartz–sulfide, and late quartz–sulfide–calcite stages. Electron microprobe analyses show that the garnet at the deposit varies in composition from And 97.95 Gro 0.41 Pyr 1.64 to And 30.69 Gro 66.69 Pyr 2.63 , and pyroxene is compositionally in the diopside–hedenbergite range (i.e. Di 90.63 Hd 8.00 Jo 1.37 –Hd 88.98 Di 4.53 Jo 6.49 ). Petrographic observations and electron microprobe analyses indicate that the sphalerite has three generations ([Zn 0.93 Fe 0.08 ]S–[Zn 0.75 Fe 0.24 ]S). The Zn associated with the first generation sphalerite replaced Cu and Fe of early xenomorphic granular chalcopyrite (i.e. [Cu 1.01 Fe 1.03 ]S 2 –[Cu 0.99 Fe 0.99 ]S 2 ), and part of the first generation sphalerite is coeval with late chalcopyrite (i.e. [Cu 0.96 Fe 0.99 Zn 0.03 ]S 2 –[Cu 1.00 Fe 1.03 Zn 0.01 ]S 2 ). Magnetite has a noticeable negative Ce anomaly (δCe = ∼0.17 to 0.54), which might be a result of the oxidized ore-fluid. Thirty δ 34 S V-PDB analyses of sulfides from the ore range from −2.3 to −0.1‰ in value, which are indicative of a magmatic source. The δ 13 C‰ and δ 18 O‰ values for calcite from the ore formed at quartz–sulfide–calcite stage vary from −9.9 to −5.5‰ and from −4.2 to 1.1‰, respectively, contrasting with δ 13 C‰ (2.9–4.8‰) and δ 18 O‰ (9.8–13.9‰) values for calcite from marble. It is suggested that the ore-forming fluid associated with late stage of mineralization was predominantly magmatic in origin with some input of local meteoric water. Molybdenite from the Haobugao deposit defines an isochron age of 142 ± 1 Ma, which is interpreted as the mineralization age being synchronous, within error, with the zircon U–Pb ages of 140 ± 1, 141 ± 2, and 141 ± 1 Ma for granite at the deposit. These data and characteristics of lithology and mineralization further show that the Zn–Fe mineralization is temporally and spatially related to the emplacement of granite in an extensional tectonic setting during the Mesozoic. [ABSTRACT FROM AUTHOR]