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Geochronology and Geochemistry of Mafic Rocks in the Xuhe, Shaanxi, China: Implications for Petrogenesis and Mantle Dynamics

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Acta Geologica Sinica(English Edition) 2015年第1期89卷 187-202页

作者： WANG Kunming WANG Zongqi ZHANG Yingli WANG Gang mlr key laboratory of metallogeny and mineral assessment Institute of Mineral Resources CAGS

The Xuhe mafic rocks, located in Ziyang county of Shaanxi Province, are dominated by diabase-porphyrite, gabbro-diabase, diabase, and pyroxene diorite. Primitive mantle-normalized multi-element patterns show that, the Xuhe marie rocks are enriched in large ion lithophile elements （LITE）, such as Ba and Pb, depleted in K and Sr for basic rocks, and are depleted in Sr, P and Ti for pyroxene diorite. Chondrite-normalized REE patterns display LREE enrichment （LaN/YbN = 9.34- 13.99） and have normalized patterns for trace element and REE similar to that of typical OIB. Detailed SIMS zircon U-Pb dating yields emplacement ages of 438.4 ± 3.1 Ma for Xuhe mafic rocks. The relatively low MgO （basic rock： 3.11-7.21 wt%; pyroxene diorite： 0.89-1.21 wt% ） and Mg# （0.20- 0.49） for Xuhe mafic rocks suggest that they were possibly originated from an extremely evolved magma. The rising parental mafic magmas underwent pyroxene and plagioclase fractionation. Crustal contamination of pyroxene diorite before emplacement occurred at a higher crustal level compared to other lithology in Xuhe mafic rocks. The degree of partial melt was low （5%-10%） and in garnetspinel transition facies. Sr-Nd isotope of pyroxene diorite and enrichment mantle characteristics for Xuhe mafic rocks suggest that mafic rocks in the North Daba Mountains were derived from a mixture of HIMU, EMII and small amount of EMI components. Furthermore, this study discusses mantle geodynamic significance of Xuhe mafic rocks in the Silurian, which indicates subduction and uplift of magma caused back-arc extension.

关键词： Xuhe mafic rock SIMS U-Pb chronology geochemistry petrogenesis mantle dynamic

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Occurrence of the Iron–rich Melt in the Heijianshan Iron Deposit, Eastern Tianshan, NW China: Insights into the Origin of Volcanic Rock–hosted Iron Deposits

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Acta Geologica Sinica(English Edition) 2018年第2期92卷 666-681页

作者： LI Houmin LI Lixing DING Jianhua LI Yanhe SONG Zhe MENG Jie MA Yubo mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesChinese Academy of Geological Sciences

Long-standing controversy persists over the presence and role of iron-rich melts in the formation of volcanic rock-hosted iron deposits. Conjugate iron-rich and silica-rich melt inclusions observed in thin-sections are considered as direct evidence for the presence of iron-rich melt, yet unequivocal outcrop-scale evidence of iron-rich melts are still lacking in volcanic rock-hosted iron deposits. Submarine volcanic rock-hosted iron deposits, which are mainly distributed in the western and eastern Tianshan Mountains in Xinjiang, are important resources of iron ores in China, but it remains unclear whether iron-rich melts have played a role in the mineralization of such iron ores. In this study, we observed abundant iron-rich agglomerates in the brecciated andesite lava of the Heijianshan submarine volcanic rock-hosted iron deposit, Eastern Tianshan, China. The iron-rich agglomerates occur as irregular and angular masses filling fractures of the host brecciated andesite lava. They show concentric potassic alteration with silicification or epidotization rims, indicative of their formation after the wall rocks. The iron-rich agglomerates have porphyritic and hyalopilitic textures, and locally display chilled margins in the contact zone with the host rocks. These features cannot be explained by hydrothermal replacement of wall rocks （brecciated andesite lava） which is free of vesicle and amygdale, rather they indicate direct crystallization of the iron-rich agglomerates from iron-rich melts. We propose that the iron-rich agglomerates were formed by open-space filling of volatile-rich iron-rich melt in fractures of the brecciated andesite lava. The iron-rich agglomerates are compositionally similar to the wall-rock brecciated andesite lava, but have much larger variation. Based on mineral assemblages, the iron-rich agglomerates are subdivided into five types, i.e., albite-magnetite type, albite-K-feldspar- magnetite type, K-feldspar-magnetite type, epidote-magnetite type

关键词： iron-rich agglomerates iron-rich melt volatile submarine volcanic iron deposit,Heijianshan Eastern Tianshan

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Apatite Fission Track Ages in the Duolong Ore District and the Uplift Time of the Qiangtang Terrrane, Tibet

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Acta Geologica Sinica(English Edition) 2018年第1期92卷 408-409页

作者： YANG Huanhuan TANG Juxing SONG Yang LIU Zhibo LIN Bin mlr key laboratory of metallogeny and mineral Resource assessment Institute of Mineral Resources Chinese Academy of Geological Sciences

Objective Fission track （FT） analysis has developed into one of the most useful techniques throughout the geologic community to reconstruct low-temperature thermal historyof rocks over geological time （Reiners et al., 2005）. The FT method is based on the accumulation of narrow damage trails （i.e., fission tracks） in uranium-rich mineral grains （e.g., apatite, zircon, titanite） and natural glasses, which form as a result of spontaneous nuclear fission decay of 238U in nature. Apatite Fission Track （AFT） has been used in many places in Tibet to study the Qinghai- Tibetan Plateanuplifl-exhumation history. However, few AFT studies have been reported in the Duolong ore district. The Duolong ore district is one of the most important ore districts in the Bangong Co-Nujiang metallogenic belt, Tibet （Lin Bin et al., 2017） and the uplift-exhumation of the Duolong ore district is closely related to the evolution of the Qiangtang Basin. Therefore, AFT of the Duolong ore district will provide important information about the uplift-exhumation history of the Duolong ore district and the Qiangtang Basin.

关键词： Apatite Fission Track Ages the Duolong Ore District the Uplift Time of the Qiangtang Terrrane

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Syn-mineralization Uplifting and Exhumation of Porphyry Systems in China:Evidence from Fluid Inclusion Data

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Acta Geologica Sinica(English Edition) 2022年第1期96卷 240-247页

作者： ZHOU Aorigele ZHENG Ming TANG Juxing HE Wen CHEN Hongjin mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

In order to understand how the metallogenic process of porphyry deposit specifically and directly respond to regional uplifting and exhumation,we compiled previous fluid inclusion data of 32 porphyry deposits in China by recalculating the fluid trapping depths and trapping depth reduction magnitude from early to late mineralization stage *** data reveal that the average trapping pressure ratio(Ave TP_(E)/TP_(L))between early-and late-stage veins of the these deposits are 1.2-18.4,mainly in the range of 1.35-5.83,with average trapping pressure reduction(1-Ave TP_(L)/TP_(E))from early-to late-stage veins are 17%-95%,and mainly in the range of 25%-83%.The fluid trapping pressure based mineralization depths most of the porphyry deposits in China had decreased from early to late vein stages by at least 450 m(900-5800 m predominant),or greater than 950 m when take the average depth reduction value,which is greater than the current gap between early-and late-stage veins of each *** propose that the apparently greater mineralization depth reduction magnitude than the current elevation gaps between early and late veins are likely a consequence of synmineralization uplifting and exhumation process that often occurs in porphyry systems.

关键词： fluid inclusion syn-mineralization uplifting exhumation porphyry deposit

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The Ore-forming Mechanism of the Jiajika Pegmatite-Type Rare Metal Deposit in Western Sichuan Province:Evidence from Isotope Dating

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Acta Geologica Sinica(English Edition) 2013年第1期87卷 91-101页

作者： LI Jiankang WANG Denghong CHEN Yuchuan mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResoucesCAGS Colleage of Earth Science and Resources Chang'an University

Granitic pegmatites are commonly thought to form by fractional crystallization or by liquid immiscibility of granitic magma; however, these proposals are based mainly on analyses of fluid and melt inclusions. Here, we use the Jiajika pegmatite deposit, the largest spodumene deposit in Asia, as a case study to investigate ore forming processes using isotope dating. Dating of a single granite sample from the Jiajika deposit using multiple methods gave a zircon U-Pb SHRIMP age of 208.4 ~ 3.9 Ma, an 4~Ar/39Ar age for muscovite of 182.9 ~ 1.7 Ma, and an 4~Ar/39Ar age for biotite of 169.9 ＋ 1.6 Ma. Based on these dating results and the 4~Ar/39Ar age of muscovite from the Jiajika pegmatite, a temperature-time cooling track for the Jiajika granite was constructed using closure temperatures of the different isotope systems. This track indicates that the granite cooled over ^-40 m. y., with segregation of the pegmatite fluid from the granitic magma at a temperature of ~700~C. This result suggests that the Jiajika pegmatite formed not by fractional crystallization, but by segregation of an immiscible liquid from the granitic magma. When compared with fractional crystallization, the relatively early timing of segregation of an immiscible liquid from a granitic magma can prevent the precipitation of ore-forming elements during crystallization, and suggests that liquid immiscibility could be an important ore-forming process for rare metal pegmatities. We also conclude that isotope dating is a method that can potentially be used to determine the dominant ore-forming processes that occurred during the formation of granite-related ore deposits, and suggest that this method can be employed to determine the formation history of the W-Sn ore deposits found elsewhere within the Nanling Metallogenic Belt.

关键词： isotope dating liquid immiscibility in granitic magmas pegmatite Jiajika rare metal deposit

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Application of Hydrothermal Diamond Anvil Cell to Homogenization Experiments of Silicate Melt Inclusions

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Acta Geologica Sinica(English Edition) 2014年第3期88卷 854-864页

作者： LI Jiankang LI Shenghu mlr key laboratory of metallogeny and mineral assessment Institute of Mineral Resources Chinese Academy of Geological Sciences China University of Geosciences

The homogenization of silicate melt inclusions （SMIs）,small droplets of silicate melt trapped in magmatic minerals,is an important component of petrogenetic and magmatic *** homogenization experiments on SMIs use microscope-mounted heating stages capable of producing high temperatures at 1 atm and cold-seal high-pressure *** stages are generally used for SMIs with low internal pressures and allow in situ observations of the homogenization *** contrast,cold-seal high-pressure vessels are generally used to heat SMIs that have high internal pressures,although the homogenized SMIs can only be observed after quenching in this *** we outline an alternative approach that uses a hydrothermal diamond anvil cell （HDAC） apparatus to homogenize *** is the only current method wherein phase changes in high-internal-pressure SMIs can be observed in situ during homogenization experiments,which represents an advantage over other conventional *** an HDAC apparatus prevents high-internal-pressure SMIs from decrepitating during heating by elevating their external pressure,in addition to allowing in situ observations of *** type-V HDAC that is currently being used has a shorter distance between the sample chamber and the observation window than earlier types,potentially enabling continuous observation of the processes involved in heating and SMI homogenization through an objective lens with a long working *** experiments using HDAC require that a number of steps,including HDAC preparation,sample preparation,sample loading,preheating,and formal heating,be carefully *** experiments on SMIs within granite samples from the Jiajika pegmatite deposit （Sichuan,China） are best performed using an HDAC-based approach,because the elevated proper external pressure of these SMIs,combined with a short heating duration,helps to suppress material leakage and any reactions within the SMIs,in add

关键词： silicate melt inclusions homogenization experiments hydrothermal diamond anvil cell,cold-seal pressure vessel Jiajika pegmatite deposit

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Chemical and Isotopic Characteristics of the Water and Suspended Particulate Materials in the Yangtze River and Their Geological and Environmental Implications

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Acta Geologica Sinica(English Edition) 2014年第1期88卷 276-360页

作者： DING Tiping GAO Jianfei TIAN Shihong SHI Guoyu CHEN Feng WANG Chengyu LUO Xurong HAN Dan mlr key laboratory of metallogeny and mineral assessment Institute of Mineral Resources CAGS Open Research laboratory of Isotope Geology Hydrological Bureau CWRC

The chemical and isotopic characteristics of the water and suspended particulate materials（SPM） in the Yangtze River were investigated on the samples collected from 25 hydrological monitoring stations in the mainsteam and 13 hydrological monitoring stations in the major tributaries during 2003 to 2007. The water samples show a large variation in both δD（ 30‰ to 112‰） and δ18O（ 3.8‰ to 15.4‰） values. Both δD and δ18O values show a decrease from the river head to the Jinsha Jiang section and then increase downstream to the river mouth. It is found that the oxygen and hydrogen isotopic compositions of the Yangtze water are controlled by meteoric precipitation, evaporation, ice（and snow） melting and dam building. The Yangtze SPM concentrations show a large variation and are well corresponded to the spatial and temporal changes of flow speed, runoff and SPM supply, which are affected by the slope of the river bed, local precipitation rate, weathering intensity, erosion condition and anthropogenic activity. The Yangtze SPM consists of clay minerals, clastic silicate and carbonate minerals, heavy minerals, iron hydroxide and organic compounds. From the upper to lower reaches, the clay and clastic silicate components in SPM increase gradually, but the carbonate components decrease gradually, which may reflect changes of climate and weathering intensity in the drainage area. Compared to those of the upper crust rocks, the Yangtze SPM has lower contents of SiO2, CaO, K2 O and Na2 O and higher contents of TFe2 O3 and trace metals of Co, Ni, Cu, Zn, Pb and Cd. The ΣREE in the Yangtze SPM is also slightly higher than that of the upper crust. From the upper to lower reaches, the CaO and MgO contents in SPM decrease gradually, but the SiO2 content increases gradually, corresponding to the increase of clay minerals and decrease of the carbonates. The δ30SiSPM values（ 1.1‰ to 0.3‰） of the Yangtze SPM are similar to those of the average shale, but lower than those of the granite rock

关键词： Yangtze River stable isotopes water chemistry Suspended Particulate Materials(SPM) hydrology environmental implication

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Chemical and Isotopic Characters of the Water and Suspended Particulate Materials in the Yellow River and Their Geological and Environmental Implications

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Acta Geologica Sinica(English Edition) 2016年第1期90卷 285-351页

作者： DING Tiping GAO Jianfei TIAN Shihong WANG Huaibai LI Ming WANG Chengyu LUO Xurong HANG Dan mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesCAGSBeijing 100037China mlr key laboratory of Isotope Geology CAGSBeijing 100037China Hydrological Bureau YRCCZhengzhou 450004China

The chemical and isotopic characteristics of the water and suspended particulate materials （SPM） in the Yellow River were investigated on the samples collected from 29 hydrological monitoring stations in the mainstem and several major tributaries during 2004 to 2007. The JD and δ^18O values of the Yellow River water vary in large ranges from -32%0 to -91‰ and from -3.1‰ to -12.5‰, respectively. The characters of H and O isotope variations indicate that the major sources of the Yellow River water are meteoric water and snow melting water, and water cycle in the Yellow River basin is affected strongly by evaporation process and human activity. The average SPM content （9.635 g/L） of the Yellow River is the highest among the world large rivers. Compared with the Yangtze River, the Yellow River SPM has much lower clay content and significantly higher contents of clastic silicates and carbonates. In comparison to the upper crust rocks, the Yellow River SPM contains less SiO2, CaO, K2O and Na2O, but more TFe203, Co, Ni, Cu, Zn, Pb and Cd. The abnormal high Cd contents found in some sample may be related to local industrial activity. The REE contents and distribution pattern of the Yellow River SPM are very close to the average value of the global shale. The average δ^30Sisp in the Yellow River （-0.11‰） is slightly higher than the average value （-0.22‰） of the Yangtze River SPM. The major factors controlling the δ^30Si SPM of the Yellow River are the soil supply, the isotopic composition of the soil and the climate conditions. The TDS in the Yellow River are the highest among those of world large rivers. Fair correlations are observed among Cl, Na^＋, K^＋, and Mg^2＋ contents of the Yellow River water, indicating the effect of evaporation. The Ca^2＋ and Sr^2＋ concentrations show good correlation to the SO42 concentration rather than HCO3-concentration, reflecting its origin from evaporates. The NO3-contents are affected by farmland fertilization. The Cu, Zn and Cd contents in

关键词： Yellow River stable isotopes water chemistry suspended particulate materials (SPM) hydrology environmental implication

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SHRIMP Zircon U-Pb Dating of Alkaline Dykes in the Pobei Area,Beishan Rift,Xinjiang Autonomous Region,China:Implications for Tectonic Setting and Mantle Plume Events

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Acta Geologica Sinica(English Edition) 2012年第4期86卷 879-884页

作者： MAO Jingwen Franco PIRAJNO ZHANG Zuoheng WAN Yusheng mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesChinese Academy of Geological Sciences Geological Survey of Western Australia 100 Plain StreetEast PerthWA 6004Australia mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesChinese Academy of Geological Sciences Institute of Geology Chinese Academy of Geological Sciences

In the Beishan rift in the eastern Tianshan orogen, Xinjiang Province, a N-S-trending dyke swarm is present in the Pobei area. The swarm cuts through the 270-290 Ma mafic-ultramafic intrusions associated with Ni-Cu sulphide mineralization. These mafic-ultramafic intrusions are typically found along E-W major faults in the Tianshan orogenic belts. We report SHRIMP U-Pb dating of zircons from a dyke of alkaline composition, which yielded a mean age of 252~9 Ma. Alkaline dykes of the same age are found in the Altay region of Siberia. This age is younger than the 270-290 Ma intraplate magmatic events that produced the mafic-ultramafic intrusions in the region, but in general agreement with the 250-260 Ma Permian plume event that gave rise to the Siberian traps and the Emeishan flood basalts in SW China. We suggest that there is a link between the Emeishan event and the dyke swarm in the Beishan rift and that the intraplate magmatism at 270-290 Ma reflects an early stage of mantle plume activity. The N-S trending dyke swarm in the Beishan rift may represent a later stage in the evolution of mantle plume activity in the NW and SW of China. We also speculate that in Beishan rift and possibly elsewhere in the Tianshan region, the dykes fed basaltic volcanism, whose products have since been eroded due to the strong uplift of the Tianshan orogen as a result of the IndiaEurasia collision in the Cenozoic.

关键词： Alkaline dykes SHRIMP tectonic setting mantle plume China

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Magmatic Evolution and mineralization Process of the Super-Large Shihuiyao Rb–Nb–Ta Deposit,Southern Great Xing'an Range,China

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Acta Geologica Sinica(English Edition) 2016年第6期90卷 2275-2276页

作者： ZHOU Zhenhua CHE Hewei MA Xinghua GAO Xu mlr key laboratory of metallogeny and mineral assessment Institute of Mineral ResourcesChinese Academy of Geological Sciences School of Earth Science and mineral Resources China University of Geosciences

Rare metal ore reserves are an important strategic resource, and their metallogenic mechanism and mineralization studies have also been received widespread international attention.

关键词： In Nb Magmatic Evolution and mineralization Process of the Super-Large Shihuiyao Rb Ta Deposit,Southern Great Xing’an Range,China

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