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China is facing many challenges in the area of high‐precision exploration for deep mineral resources, and also in environmental and engineering fields. It has become an urgent task to realize geophysical explorations with high precision and high efficiency in complex environments. It has been found that the traditional transient electromagnetic method (TEM) had a series of problems related to theory, method, and instrument, as well as data interpretation. Based on the reviews of present TEM achievements, three new improved measurements are introduced. The central‐loop system was improved by a large fixed‐loop system; the long‐offset system was changed to the short‐offset one; the resistivity profile was transformed into a virtual wave‐field profile. Finally, this paper points out that the future research direction of the TEM method is in terms of equipment, data processing, and big data information. [ABSTRACT FROM AUTHOR]

The Jurassic shale is an important source rock for the found gas reservoirs in the Tarim Basin, northwestern China, but has never been researched for shale gas potential. The geological effects on methane adsorption capacity for the gas shale have been investigated in this paper through the geochemical, mineralogical and adsorption analyses on samples from wells and sections. The methane adsorption capacity ranges from 0.58 to 16.57 cm3/g, and the total organic carbon (TOC) content is between 0.5 and 13.5 wt%. The organic maturity measured by Tmax is between 410 °C (immature) and 499 °C (overmature). The methane adsorption capacity of the Jurassic continental shale in the Tarim Basin is affected by many geological factors, including the TOC content, organic matter maturity, mineral composition, surface area and pore size distribution. The TOC content is the most significant factor with a positive effect on the adsorption capacity of the Jurassic shale, and the influence varies piecewise according to the TOC content. The TOC content contributes much more to the methane adsorption capacity of organic-rich shale samples (TOC content > 0.7 wt%) than to the organic-lean samples (TOC content < 0.7 wt%). The mineral composition is a secondary factor, and the abundance of clay content has a positive effect on the methane adsorption capacity despite its relatively weaker adsorption ability compared to TOC. The pore size distribution has different effects on surface area and pore volume. Mesopores and micropores provide the major surface area and are mainly derived from TOC and illite, which has a positive influence on the adsorption capacity. Mesopores and macropores offer the major pore volume and are mainly formed by illite, which is the major contributor for pore volume rather than surface area. In addition, the TOC and illite contents of the Jurassic shale in the Tarim Basin are closely related to the origin, maturity and diagenesis evolution of the shale: (1) both TOC and illite content variations are related to the different provenances and depositional environments of shale; (2) the decrease of TOC content with increasing maturity is also partly attributed to hydrocarbon generation; and (3) the increase of illite content with increasing maturity is due to illitization in the diagenesis of shale. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper addresses the surface and Holocene aeolian deposits in the southeastern Mu Us Desert, N. China, systematically analysing the evolution of the geochemical characteristics of aeolian sand-palaeosol sequences and their environmental significance. Our results indicate that the geochemical components of the Holocene aeolian deposits and surface deposits had the similar material sources, sediment transport and deposition processes in the study region, which were dominated by SiO2, Al2O3, and Na2O. In the weathering process of the Jinjie (JJ) profile, the Na, K, and Si presented the slight leaching and migration in general, while the other elements were relatively accumulated. The Holocene aeolian deposits and surface deposits incurred weaker geochemical weathering under cold and dry conditions and were only weakly leached, which implies a relatively arid environment in the Holocene epoch and the modern era. The weathering degree was controlled by the regional temperature and precipitation, and was probably more sensitive to the precipitation changes. In the sedimentary profile, the geochemical parameters and migration of elements demonstrated that there have been several alternating warm-wet and cold-dry intervals in the Mu Us Desert in the Holocene epoch; there were relatively warm and wet conditions prior to 4.6 ka, and it has been cold and dry since then. Six millennial-scale dry events were recorded during the Holocene, which were not only accordant with the history of palaeoclimatic changes in the different latitudes and archives of the Northern Hemisphere, but also correspond to the millennial-scale variation of cosmic radiation and solar activity during that period. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Dashui porphyry granitoids in the western Qinling Orogen are spatially associated with the Dashui gold deposit, but their ages and tectonic setting have not been well defined yet in previous studies. This paper reports the results and understandings obtained from our original study in geochronology and isotope and element geochemistry. SHRIMP zircon U-Pb dating yielded ages of 213.7 ± 2.7 Ma for granitic stock and 215.1 ± 2.5 and 210.2 ± 1.6 Ma for granitic dikes. The granitoids are characterized by high LREE but low HREE and HFSE. They have (87Sr/86Sr) i ratios of 0.706 to 0.709 and εNd(t) values of −5.3 to −7.6. The majority of zircons in the Dashui granitoids have εHf(t) values ranging from −6.2 to 6.7 and TDM2(Hf) ages from 743 to 1464 Ma. The isotope signatures, together with La/Y and Mg# values, show that the magmas are mainly sourced from partial melting of a subducted slab, and possibly assimilated immature sediments during upward migration. Thus, the Dashui granitoids most likely formed in a volcanic arc where supra-subduction zone melts assimilated lower crustal material no later than 215 Ma. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Naotic dissepiments are special structures of rugose corals, characterized by a column of distally arched plates at peripheral parts of thick septa or within the cystozone. In this study, naotic‐dissepimented colonial rugose corals Gyanyimaphyllum crassiseptatum and Ipciphyllum naoticum and their associated microfacies were documented from the Late Permian Gyanyima section in Tibet, southwestern China. The morphology of the Gyanyima naotic‐dissepimented corals is cerioid massive forms or fasciculate forms with connected individuals, with broken skeletons. Between coral colonies and/or skeletons, the interspaces are occupied by highly fragmented bioclasts and sparry calcite. These biotic and sedimentary characteristics suggest that the Gyanyima naotic‐dissepimented corals could have developed in high water‐energy environments above fair‐weather wave‐base. This implies that the development of naotic dissepiments was probably related to an enhanced hydrodynamic force. According to a review on the Permian naotic‐dissepimented rugose corals in China, they are mainly composed of massive colonial forms with a few fasciculate colonial and solitary forms. Current available data indicate that they could occur in bioclastic grainstones and oncoid limestones with eroded skeletons, which also support a conclusion that naotic dissepiments formed in turbulent environments. Based on the ontogenic studies on naotic‐dissepimented rugose corals, naotic dissepiments occur sporadically in the neanic stage and are well developed but not permanently and uniformly in adult stage. Furthermore, different species in the same genus have different degrees of development of naotic dissepiments, which might imply that naotic dissepiments are not suitable to be an important taxonomic character in higher than species level. [ABSTRACT FROM AUTHOR]

Based on a detailed morphologic and tomologic investigation of a fossil endocarp, a new species of Diploclisia (Menispermaceae) is described from the Late Miocene of Jiahu, Zhejiang Province, eastern China. This represents the first record of the genus in the Neogene. The fossil endocarp closely resembles that of the Chinese endemic, Diploclisia affinis. The past and present distribution of Diploclisia shows that the genus probably originated in north‐east China in the Palaeocene (66–56 Ma) at the latest, which has undergone various phases of expansion and contraction. The more advanced Diploclisia glaucescens probably expanded into south and south‐east Asia in the Pleistocene, when global sea‐levels were lower. [ABSTRACT FROM AUTHOR]

China ranks as the world's largest gold producer and as the second largest gold consumer since the last few years and hosts one of the fastest growing gold markets in the world. The gold mineralization in China has been divided into several super‐large (>100 t Au), large (50 to 100 t Au), and numerous medium to small (20 to 50 and <20 t Au) deposits. Geologically, these are classified into different types such as gold‐only deposits, base metal‐rich type including skarn, porphyry, and vein deposits, and placer accumulations. Integrated genetic models based on geological investigations propose that the gold deposits formed through multiple stages of subduction–accretion–collision associated with different orogenic cycles, with most of the giant gold deposits related to extensive lithospheric destruction and recycling. China has a long history of gold mining starting from the days of the Xia, Shang, and Zhou Dynasties at ca. 2,100–256 bc, which further flourished in the "Silk Road" era, although in the modern times, the country was "officially" reported producing hardly 2 tons of gold for nearly 40 years until a major revival occurred between 1982 and 1993, with a dramatic increase to 160 tons per year. According to recent statistics, China ranks as the world's largest producer of gold with over 460 tons, contributing significantly to the growth of world gold production. In the Asian region, 91% of gold production comes from China and five other countries, with China contributing the major share. With regard to gold consumption, the amount of gold bought in China rose steadily over the past several years from around 204.5 tons in 2002 to 832.18 tons in 2012. Among the various forms of gold jewellery in China, fine gold is the most popular, with 24 K gold accounting for more than 80% of the gold jewellery sold in the country. Studies identify a positive relationship between the rate of technical expertise and economic growth in state‐owned and mixed sectors of gold industry in China. Attracting more private investment into capital‐intensive and state‐owned sectors is considered to help boost the mining industry. China's gold output sustained the world gold market even during the global financial crisis in other bulk commodities. Quantitative analysis in recent studies reveals a power‐law cross‐correlation between price and volume in gold spot and futures markets and predicts long‐term stability despite short‐term fluctuations. Extensive mining activities invariably raise environmental issues and anthropogenic health hazards. With the country announcing the discovery of new gold deposits, such as the biggest ever gold mine in Shandong with gold resources valued more than $22 billion, and moving forward to new horizons in gold mining and production, insightful policies from decision makers are important in the areas of promoting research and development in academic and technical fields, involving technical expertise and advanced technology in gold mining and processing, and implementing strict regulations for environmental protection. [ABSTRACT FROM AUTHOR]

The Jiaodong gold province in northeastern China is the country's premier gold resource and globally one of the most important gold provinces. The late Early Cretaceous gold metallogeny in this belt remains an enigma as it is hosted in the Archean Jiaobei Terrane of the North China Block and, to a lesser extent, within the Palaeoproterozoic Sulu Terrane of the South China Block. The driving force for widespread Late Jurassic and Early Cretaceous granitic magmatism, the switchover from a compressional to extensional tectonic regime, and gold mineralization are considered to be a combination of plate subduction with lithospheric delamination and consequent asthenospheric upwelling. Although many aspects related to the genesis of the gold deposits in Jiaodong have been resolved, the spatial distribution of the world‐class gold deposits in this belt, which is of vital importance to brownfields and greenfields exploration, has been poorly understood in terms of the structural evolution of the province. In the northwestern segment of the Jiaobei Terrane, the world‐class gold deposits of Sanshandao in the west, through Jiaojia, to Linglong in the east define a broadly E–W corridor. This corridor links a series of east‐verging jogs on ore‐controlling NNE‐trending oblique‐slip faults that are subparallel to an lithospheric‐scale Tan‐Lu Fault to the west. There is cryptic evidence that these jogs line up in the E–W trend due to reactivation of Palaeoproterozoic to Mesozoic faults and folds that were part of the structural architecture of the terranes prior to the gold event. These jogs induced deviations in the local principal stresses relative to regional equivalent stresses, with resultant heterogeneous strain, increased rock permeability, and focussed ore‐fluid ingress. Both disseminated/microbreccia‐stockwork and vein‐type gold deposits formed in this corridor, with the former being predominant and the latter having a higher gold grade. In contrast, predominant vein‐type gold deposits in the eastern segment of the Jiaobei and Sulu terranes tend to form N–S corridors. These vein‐type ores may relate to rotational strain induced by movement on pairs of more linear NNE‐trending faults with the same kinematic movement sense. [ABSTRACT FROM AUTHOR]

By integrating diagenesis and sedimentary facies, the distribution of diagenetic alterations and their impacts on reservoir quality were investigated within a lacustrine fan delta depositional environment in the Lower Cretaceous of the Western sub-sag in the Chagan Sag, Yin-E Basin, northern China. Core observation and analyses of petrography and geochemistry of the sandstones revealed that the eogenetic alterations display spatial and temporal distribution patterns associated with sedimentary facies, including distributary channels of a fan delta front (DC), distributary bays (DB) and sheet sands (SS) and mouth bar (MB) (SS and MB are collectively referred to as S). Percolation of meteoric waters occurring in high permeability DC sandstones resulted in leaching of feldspar, the formation of kaolinite, as well as mechanical infiltrated clays around detrital grains. Conversely, the DB deposits containing abundant ductile lithic fragments were subjected to mechanical compaction and thus the development of a pseudomatrix. During a long burial residence time (the Early Cretaceous period) in a lacustrine environment, abundant early carbonate cements were precipitated, especially in the distal S sandstones. The sandstones lacking eogenetic cements were subjected to stronger mechanical compaction. Additionally, eogenetic alterations have an important impact on the distribution of the mesogenetic alterations. Sandstones containing few eogenetic cements or thin or discontinuous infiltrated clay rims around the detrital grains were subjected to quartz cementation. However, during the hydrocarbon generation stage, the most efficient percolation of meteoric waters and organic acid dissolved feldspar minerals and carbonate cements, resulted in DC sandstones having more intragranular and intergranular porosity. Owing to high matrix contents and early calcite cement contents, the DB and S sandstones had lower permeability and were rarely dissolved. During the late mesogenetic stage, late carbonate cements occurred in all sedimentary facies and iron and magnesium ions were released from the transformation from kaolinite to illite or to chlorite. The results from this study show possible diagenetic evolutionary pathways in the reservoir sandstones within the fan delta depositional environment, which in turn provides some insights into the controls on reservoir potential. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wind is the primary control on the formation of aeolian geomorphology. In this study, we combined wind regime data from automated weather stations in the western and southwestern Tengger Desert of the Inner Mongolia region in China with remote-sensing data to analyse the relationship between the wind energy environment and aeolian geomorphology. Tengger Desert is one of the main dust storm sources in northwestern China. Therefore, efforts aimed at controlling desertification and dust storm require a deeper understanding of the processes that govern the formation and subsequent evolution of dunes in this area. Wind speed was largest in the northwest (3.3 m/s in the Xiqu station) and smallest in the southeast (1.2 m/s in the Haizitan station). Potential sand transport was also largest in the northwest (195 in the Jiahe station) and smallest in the southeast (33 in the Tumen station). The sand-driving wind (5.92 m/s) directions were from the NW and SE quadrant across the study area, at >76% of all sand-driving wind, reaching 99% in the Tumen station. The sand-driving wind in the NW quadrant reached >48%, and in the SE quadrant, >12% of all sand-driving wind in all stations. In the study area, sand dunes included crescent, dune networks, transverse, and coppice dunes. Dune crest directions had similar trends from upwind to downwind, at 133° in the middle region, and 124° in the southwestern region. Mean dune spacing changed with dune patterns; the maximum spacing for crescent dunes was 147 m, for dune networks 118 m, and for transverse dunes it was 77 m. The mean crest length was 124m (maximum) for crescent dunes in the northwest, 121m for transverse dunes, and 84m for dune networks. However, because of gullies in the southern region, the mean crest length was only 58m (least) for the crescent dunes in that area. The defect density ranged from 0.007 to 0.014. The spatial differences in dune patterns reflected the evolution of the dune field, where older dunes had been formed upwind and younger downwind. [ABSTRACT FROM AUTHOR]

Pressure measurements using drill stem tests and estimates from log data calculation indicate that three vertically stacked regional pressure compartments exist in the Qikou Depression of Bohai Bay Basin, N. China. The compartments comprise hydrostatic, upper weak, and lower overpressure systems. Laterally, overpressure (pressure coefficient > 1.2) occurs in the deeper areas and weakens gradually from the centre to the margin of the depression. The accumulation of oil and gas exhibits the interesting characteristics of oil-bearing layers above gas-bearing layers in the Qikou Depression. The pattern can be accounted for by the evolution of overpressure system, the maturity process of the source rock and the main fault activity. In the late Dongying Formation (Ed, 30 Ma), the lower overpressure system began to form shape, and the hydrocarbon sources generated a large volume of oil. However, because there was no migration pathway, the oil only accumulated in the original strata. In the late Guantao Formation (Ng, 12 Ma), the gas was generated, the upper overpressure system formed gradually, and the activity of the main fault gradually increased. Then, the overpressure pushed the early gathered oil to flow from the lower overpressure system into the upper overpressure system. Afterwards, the activity of the main fault decreased again and remains weak until now. Thus, later generated natural gas cannot keep migrating along the main fault and can only accumulate in the lower overpressure system. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The southern Great Hinggan Range in northeast China, mainly bounded by the Kangbao-Chifeng Fault to the south and the Hegenshan-Heihe Suture to the north, is a Palaeozoic subduction-related accretionary belt added to the northern margin of the North China Craton. The area has been considered as a Yanshanian metallogenic province, with more than 20 Mo deposits being discovered. Recently, six of the Mo deposits were proven to have formed during the Indosinian (Triassic) Orogeny, indicating the significance of the Indosinian mineralization, orogeny and magmatism. In this contribution, we summarize available data of the Indosinian Mo deposits, and show that Triassic Mo mineralization occurred in the time range of 248-232 Ma, coincident with a regional granitic event, and was presented as porphyry and intrusion-related quartz vein systems. The Indosinian ore-related granitoids show geochemical features of high-K calc-alkaline metaluminous-peraluminous and adakitic rocks, and have been formed by partial melting of thickened lower crust in a post-subduction tectonic setting. Rhenium contents of molybdenite crystals and sulphur-lead isotopic compositions indicate that the ore-forming materials originated from continental crust with some mantle components involved. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Qiaxia Cu deposit occurs as veins controlled by NW-extending structures in the Devonian volcano-sedimentary Kelan Basin of the Altay orogenic belt, Xinjiang, China. Igneous and sedimentary strata exposed in the mining area have been subjected to greenschist-facies metamorphism represented by an assemblage of chlorite-epidote-biotite ± garnet ± amphibole. The hydrothermal ore-forming process can be divided into the early, middle and late stages, represented by banded magnetite-quartz, Cu-polymetallic-quartz veins and carbonate-quartz ± pyrite veinlets, respectively. The main ore minerals including chalcopyrite and other polymetallic sulphides are revealed to have mainly formed in the middle stage. Four types of fluid inclusions (FIs), including aqueous (W-type), carbonic-aqueous (C-type), purely carbonic (PC-type) and daughter mineral-bearing (S-type), have been identified at the Qiaxia copper deposit. The early-stage quartz captures the C- and W-type primary FIs completely homogenized at temperatures of 335-388 °C with low salinities of 5.51-8.66 wt.% NaCl equiv.; whilst the late-stage quartz or calcite contains only the W-type FIs with homogenization temperatures of 122-239 °C, and salinities of 0.18-7.86 wt.% NaCl equiv. This indicates that the metallogenic system evolved from CO2-rich, metamorphic to CO2-poor, with the addition of late meteoric fluid, and that a significant CO2-escape may have occurred during the evolution. The coexistence of all four types of FIs can only be observed in the middle-stage minerals, even in the microscopic domain of a crystal, representing an association trapped from a boiling fluid system. These FIs are homogenized at temperatures ranging mainly from 288 to 329 °C, with two salinity clusters of 3.39-11.75 wt.% NaCl equiv. and 38.93-46.37 wt.% NaCl equiv., respectively. The unique CO2-rich FIs including C- and PC-types in the middle stage implies the metal precipitation results from fluid boiling, CO2-escape and transient oversaturation primarily from metamorphic devolatilization. Hence, the Qiaxia Cu deposit can be taken as an example of an orogenic lode Cu system resulting from metamorphic devolatilization in Triassic continent-continental or intercontinental collision; and a deposit-scale metallogenic model has been proposed to interpret the mechanism of formation of the Qiaxia Cu deposit. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Yangshan gold deposit, Gansu Province, is the largest gold deposit in China and the best representative of the western Qinling gold province. Granite dykes can be observed in the orefield, of which some are spatially associated with the gold orebodies. Gold mineralization was debated between magmatic hydrothermal and metamorphic hydrothermal models in previous studies due to a shortage of precise isotopic ages of the granite dykes in the orefield. In this contribution, we report in-situ zircon LA-ICP-MS U-Pb ages combined with Hf isotope and REE data. The age of granite dykes is constrained to be 220.2 ± 3.1 Ma, coeval with the regional development of Triassic granitoids, which resulted from the northward subduction of the Mian-Lue oceanic plate. The εHf(t) values of inherited and new zircon grains from the granite dykes show that the granite dykes have a complex source dominated by sediments which were sourced from the North China Craton, Yangtze Craton and Qinling Orogen, and accumulated in a fore-arc setting. The granite dykes were derived from partial melting of the fore-arc sediment prism induced by the fluids sourced from metamorphic devolatilizaiton of the underthrust Mian-Lue oceanic plate. The Yangshan gold deposit was formed at about 190 Ma, some 30 Myr later than the intrusion of the granite dykes, ruling out the possibility that gold mineralization was caused by Triassic granitic magmatism. The Yangshan gold deposit is a transitional system between Carlin- and orogenic-types that resulted from continental collision orogeny, metallogeny and fluid flow. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The East Qinling region in central China, hosting several tens of Mesozoic magmatic-hydrothermal Mo deposits, is one of the largest molybdenum belts in the world. The Zhifang Mo deposit is hosted in volcanic rocks of the Xiong'er Group in the Waifangshan area, Qinling Orogen. Previous studies variously correlated the mineralization in this deposit with Yanshanian magmatism or Palaeo-Mesoproterozoic volcanic-hydrothermal events. The orebodies are associated with quartz veins and controlled by subsidiary faults of the Machaoying Fault. The ore-forming process can be divided into the early, middle and late stages and is characterized by quartz-pyrite, quartz-polymetallic sulphide and quartz-carbonate veins, respectively. The early-stage quartz is structurally deformed, suggesting a compressional tectonic regime; the middle-stage sulphides fill the fractures of the early-stage assemblages and show no deformation, suggesting a tensional setting; the late-stage veins mostly infill the open-space fissures. Three types of fluid inclusions (FIs) are identified at the Zhifang deposit: H2O-NaCl (W-type), CO2-rich (C-type) and daughter mineral-bearing inclusions (S-type). Fluid inclusions of early-stage quartz homogenize between 380 and 470 °C, with salinities ranging from 0.4 to 9.6 wt.% NaCl equiv., whereas the late-stage calcite contains only the W-type FIs with homogenization temperatures of lower than 240 °C, and salinities of 0.4-8.7 wt.% NaCl equiv. This indicates that the ore fluid system evolved from CO2-rich, probably metamorphic hydrothermal to CO2-poor, meteoric fluid. All three types of FIs can be observed in the middle-stage quartz, and even in the microscopic domain of a crystal, suggesting that this heterogeneous association was trapped from a boiling fluid system. These FIs homogenized at temperatures ranging from 250 to 360 °C and display two salinity clusters of <18.5 and 29.1-29.9 wt.% NaCl equiv. These results suggest that metal precipitation resulted from fluid boiling. The estimated trapping pressures of FIs range from 101 to 285 MPa, suggesting an alternating lithostatic-hydrostatic fluid system, which was controlled by a fault-valve at the depth of 10 km. The δ34S values of ore minerals from the Zhifang Mo deposit show a range between −11.8‰ and 6.0‰, with a bimodal distribution. The early-stage pyrite has a positive δ34S value of 6.0‰ that is similar to the host rocks of the Xiong'er Group and the Taihua Supergroup, suggesting that the wall rocks contributed much of the sulphur to the early-stage pyrite during fluid-rock interaction. However, the δ34S values of the middle-stage sulphides have negative mean and restricted range from −11.8‰ to −4.5‰. The widespread rutile grains coexisting with molybdenite in the middle-stage correlate the negative δ34S values with relatively oxidized fluids. We consider phase separation as an efficient mechanism for ore-fluid oxidation and molybdenum deposition based on fluid inclusions and sulphur isotope data. Geological, fluid inclusion and sulphur isotope data of the Zhifang Mo deposit suggest that the Mo mineralization is unrelated to the Yanshanian magmatism or the Palaeo-Mesoproterozoic volcanic-hydrothermal event. Here we propose that the Zhifang Mo deposit may be considered as an orogenic mineral system, with its formation in an active continental margin related to the northward subduction of the Mian-Lue oceanic plate during the Triassic. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Jinlongshan gold deposit, Shaanxi Province, is a large Carlin-type deposit in the Western Qinling Gold Province (WQGP) in the Qinling Orogenic Belt, Central China. In this study, we present new EPMA and LA-ICP-MS geochemical data on the Fe-S-As minerals at Jinlongshan, which consist mainly of pyrite, arsenian pyrite and arsenopyrite. Diagenetic pyrite (Py0) is preferentially hosted in the sedimentary rocks as rounded or framboidal aggregates. Three types of hydrothermal pyrite (Py1, Py2 and Py3) and two types of arsenopyrite (Apy1 and Apy2) were newly identified in the ores and wall-rocks: fine-grained Py1 and Apy1 were formed at the early mineralization stage; coarse-grained Py2 and Apy2 were formed at the middle mineralization stage; and Py3 with stibnite were formed at the late mineralization stage. Their trace elements differ in concentrations, associations and rim-core zonations, implying different genesis and crystallization processes. Py0 is As-poor (Au < 0.105 wt% and As < 0.094 wt%); Py1 and Py2 are Au-As-rich (Au = 1.9-113 ppm and As up to 7.270 wt%); Py3 is Au-As-poor (Au = 0.03-11.4 ppm and As < 0.56 wt%); and Apy1 and Apy2 show the highest Au concentration (up to 576 ppm). Co, Ni and As (±Se and Te) occur in pyrite as isomorphism, and Ag, Cu, Pb and Zn are distributed primarily as invisible or visible sulphide inclusions. The dominant state of Au in the hydrothermal Fe-S-As minerals at Jinlongshan is lattice bound Au+1, and possibly invisible Au0 nanoparticles, whereas in the diagenetic Py0, the dominant state is mainly Au0. By integrating the evidence from ore deposit geology, mineral morphology, internal structure and trace element geochemistry of the Au-bearing Fe-S-As minerals, it is concluded that the formation of the Jinlongshan Au deposit may have been related to the regional metallogenic episode at around 170 Ma in the WQGP, which was coeval with the regional tectonic transition from a collisional compression to a late- to post-collisional extension in the Qinling Orogen. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Xunyang Hg-Sb orefield, Shaanxi Province, containing two large (Gongguan and Qingtonggou) and tens of small to medium Hg-Sb deposits, is located in the southern Qinling Orogen. Ore bodies of the deposits are hosted in Devonian dolomite and controlled by a fault system. Ores are mainly present as massive veins, disseminations, breccias and fine veinlets, with cinnabar (Hg) and stibnite (Sb) being the dominant ore minerals. Gangue minerals include quartz, calcite and dolomite. Hydrothermal minerals (quartz and calcite) only contain aqueous fluid inclusions with low homogenization temperature (135-274 °C) and salinity (1.23-12.3 wt.% NaCl equiv.), supporting an epizonogenic hydrothermal origin. The carbon, oxygen and hydrogen isotope data indicate that the ore-forming fluids were mainly sourced from epizonogenic to metamorphic devolatilization of the Sinian−Triassic strata that possibly underthrusted beneath the orefield, with inflow of the circulating meteoric water. Sulphur isotope ratios of stibnite and cinnabar range from 2‰ to 12‰, suggesting a contribution from sedimentary sulphate or sulphate-bearing fluids potted in strata, which is coincident with the δ34S values (3.4-8.6‰) of diagenetic pyrite in the strata. The conclusion drawn from sulphur isotopes is fully supported by the Pb isotope signatures. In addition, the 87Sr/86Sr ratios gradationally increase from ore-hosting dolostones, through ore-barren calcite or low-grade ores, to high-grade ores, indicating that a portion of the fluids originated from a source with higher 87Sr/86Sr values than the host-rocks, which is possibly composed of the Neoproterozoic−Lower Palaeozoic basement of the Xunyang Basin. Integrating the data from ore geology, fluid inclusion microthermometry and stable, radioactive isotope geochemistry, it can be concluded that the deposits in the Xunyang Hg-Sb orefield were formed by epizonogenic hydrothermal fluids mainly sourced from the strata via structural deformation during the North China−Yangtze continental collision. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Xiaoqinling gold field in central China is the second largest orogenic Au province in China. In the Xiaoqinling area, the Dahu Au-Mo deposit is typical because it is one of the five early-discovered large gold deposits, but also unique for its northernmost location and Mo-association. This study shows that the deposit is a fault-controlled lode system formed by a three-stage hydrothermal process. The early-stage pyrite-quartz veins are structurally deformed and broken. The middle-stage molybdenite-pyrite-quartz stockworks (mostly coaxial) infill the cracks of the early-stage veins and minerals. The late-stage open-space filling quartz-carbonate veinlets show a comb-like texture. The early- and late-stage quartz only contains the fluid inclusions of CO2-H2O and H2O-NaCl types, respectively, suggesting an evolution from CO2-rich to CO2-poor; whereas the middle-stage quartz contains fluid inclusions of CO2-H2O, H2O-NaCl, pure CO2 and daughter mineral-bearing types, supporting a boiling fluid system, because they can occur in a microscopic domain of a single crystal, homogenize divergently at similar temperatures clustering between 293 and 410 °C, and show contrasting salinities of <13.6 wt.% and >26.3 wt.% NaCl equiv. The inclusions in early-stage quartz are homogenized at 402-503 °C, with salinities of 4.5-10.4 wt.% NaCl equiv.; and those in late-stage quartz are homogenized at temperatures of <251 °C, with salinities of 14.4-14.8 wt.% NaCl equiv. The trapping pressures of inclusions are estimated to be 138-331 MPa in the early stage and 78-237 MPa in the middle stage, implying that the fluid system alternately fluctuated from lithostatic to hydrostatic, which was controlled by a fault-valve mechanism at depths of >11 km and ~7.8 km, respectively. Hydrogen and oxygen isotope signatures indicate that the fluids originated from metamorphic devolatilization in the early stage, then mixed with meteoric water in the middle stage, and finally replaced by meteoric water in the late stage. Hence, it is concluded, that metal precipitation at the Dahu deposit was mainly caused by fluid boiling, followed by fluid mixing, along with a trans-compressing at the transitional zone from a magmatic arc to back-arc basin, which resulted from the Triassic northward subduction of the Mian-Lue oceanic slab. © 2014 The Authors. Geological Journal published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR]

Ten well-preserved, earthquake-triggered liquefaction mounds and a carbonate sand volcano have been found in the Mesoproterozoic Wumishan Formation (1550-1400 Ma) in the Beijing area, North China. These features crop out in a roadcut near Zhuanghuwa Village. All ten mounds occur in the same sedimentary layer and have rounded shapes with some concentric and radial fissures arising from the centre. They range from 1.5 to 4 m in diameter and from 10 cm to 30 cm in height. The carbonate sand volcano has a diameter of 110 cm and the 'crater' at the top has a depth of about 30 cm. Associated with these mounds and the sand volcano are many 'normal' sedimentary structures and numerous soft-sediment deformation structures. The former include ripple marks, cross-bedding, stromatolites and desiccation cracks, indicating deposition in a stable shallow-water peritidal platform environment. The latter include intrastratal faults and folds, seismically formed breccias and carbonate clastic dykes. The morphological features and the genesis of these liquefaction mounds are very similar to mounds formed recently by the great Wenchuan Earthquake of China (2008). Detailed thin-section study of the mounds found no signs of any kind of biological constructional process; instead it reveals some obvious fluidification and liquefaction characteristics. Comparative studies have shown that these features are probably the products of Mesoproterozoic earthquake activity. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]