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Relationships between Basic and Silicic Magmatism in Continental Rift Settings:A Petrogeochemical Study of Carboniferous Post-collisional Rift Silicic Volcanics in Tianshan,NW China

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Acta Geologica Sinica(English Edition) 2005年第5期79卷 633-653页

作者： XIA Linqi XIA Zuchun XU Xueyi LI Xiangmin MA Zhongping WANG Lishe Xi＇ an Institute of Geology and mineral resources China Geological Survey Xi＇ an Shaanxi 710054

Petrogeochemical data are reported for silicic volcanic rocks from the Tianshan Carboniferous rift, with the aim of discussing the petrogenesis of silicic magmas. Incompatible element vs. incompatible element diagrams display smooth positive trends for the Tianshan Carboniferous rift-related volcanic rocks; the isotope ratios of the silicic lavas [^87Sr/^86S（t）=0.699880.70532; eNd（t）=4.76-8.00; ^206pb/^204pb（t）=17.435-18.017; ^207Pb/^204Pb（t）=15.438-15.509; ^208Pb/^204Pb（t） = 37.075-37.723] encompass those of the basic lavas. These data suggest a genetic link between rhyolites and basalts, but are not definitive in establishing whether silicic rocks are related to basalts through fractional crystallization or partial melting. Geochemical modeling of incompatible vs. compatible elements excludes the possibility that silicic melts are generated by the melting of basaltic rocks, and indicates a derivation by fractional crystallization plus moderate assimilation of wall rocks （AFC） starting from intermediate rocks to silicic rocks. Continuous AFC from basalt to rhyolite, with small rates of crustal assimilation, best explains the geochemical data. The presence or absence of bimodal volcanism （the ＂Daly Gap＂） might be related to cooling rates of magma chambers. In central and eastern Tianshan, the crust was thinner and the cooling rates of the magma chamber within the crust were greater. These conditions resulted in a rapid fall in temperature within the magma reservoir and caused a narrow temperature interval over which intermediate melts formed, effectively reducing the volume of the intermediate melts.

关键词： Carboniferous rift-related silicic volcanic rocks geochemistry bimodal volcanism Tianshan NW China.

Ore Forming Fluids of Several Gold Deposits in the Irtysh Gold Belt, Xinjiang, China

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Journal of Earth Science 2020年第2期31卷 298-312页

作者： Yingwei Wang Jiuhua Xu Rufu Ding Hui Zhang Xihui Cheng Chunjing Bian shaanxi Institute of geological survey Xi'an 710054China shaanxi mineral resources and geological survey Xi'an 710068China Department of Resource Engineering University of Science and TechnologyBeijing 100083China China Non-Ferrous Metals resources geological survey Beijing 100012China

The metallogenic environment of the Irtysh gold belt in Xinjiang is studied in *** metallogenic geological background,metallogenic conditions and ore-controlling factors of the gold deposits in eastern,central and western regions of the metallogenic belt are *** metallogenic structure of the Irtysh tectonic belt has the characteristics of diverging to the west and converging to the *** ore controlling by ductile shearing and magmatic activity in Irtysh gold belt result in zoned and segmented distribution of gold *** the fluid inclusion research and H-O-S isotope analysis,the evolution regularity of gold ore-forming fluids in the region was *** radiation X-ray fluorescence was used to analysis the concentration of metal elements in a single fluid inclusion,explaining the occurrence and migration process of Au in hydrothermal *** source of ore forming minerals in western gold deposit is more closely related to magmatic activity,and the structural metamorphism of eastern gold deposit has greater influence on *** fluids of gold deposits are characterized by metamorphic water(and magmatic water)in the early stage and mixed with meteoric water in the late *** the metallogenic elements are enriched in CO2 rich *** Au is mainly activated,migrated and enriched with the mixed fluid of magmatic hydrothermal,metamorphic hydrothermal and atmospheric precipitation in the medium-low temperature,shallow to medium-deep environment.

关键词： Irtysh gold belt ore forming fluids H-O-S isotope synchrotron radiation X-ray fluorescence metallogenic model

Reassessment of petrogenesis of Carboniferous—Early Permian rift-related volcanic rocks in the Chinese Tianshan and its neighboring areas

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Geoscience Frontiers 2012年第4期3卷 445-471页

作者： Linqi Xia Xueyi Xu Xiangmin Li Zhongping Ma Zuchun Xia Xi＇an Institute of Geology and mineral resources China Geological Survey Xi＇an Shaanxi 710054 China

The Carboniferous-Early Permian rift-related volcanic successions, covering large areas in the Chinese Tianshan and its adjacent areas, make up a newly recognized important Phanerozoic large igneous province in the world, which can be further divided into two sub-provinces： Tianshan and Tarim. The regional unconformity of Lower Carboniferous upon basement or pre-Carboniferous rocks, the ages （360--351 Ma） of the youngest ophiolite and the peak of subduction metamorphism of high pressure-low temperature metamorphic belt and the occurrence of Ni-Cu-bearing mafic-ultramafic intrusion with age of ~352 Ma and A-type granite with age of ~358 Ma reveal that the final closure of the Paleo-Asian Ocean might take place in the Early Mississippian. Our summation shows that at least four criteria, being normally used to identify ancient asthenosphere upwelling （or mantle plumes）, are met for this large igneous province：（1） surface uplift prior to magmatism; （2） being associated with continental rifting and breakup events; （3） chemical characteristics of asthenosphere （or plume） derived basalts; （4） close links to large-scale mineralization and the uncontaminated basalts, being analogous to those of many ＂ore-bearing＂ large igneous provinces, display Sr-Nd isotopic variations between plume and EMI geochemical signatures, These suggest that a Carboniferous asthenosphere upwelling and an Early Permian plume played the central role in the generation of the Tianshan--Tarim （central Asia） large igneous province.

关键词： Carboniferous-Early Permian rift-related volcanism Tianshan-Tarim (central Asia) large igneous province Asthenosphere Mantle plume Lithosphere contamination

Mid—Late Neoproterozoic rift-related volcanic rocks in China:geological records of rifting and break-up of Rodinia

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Geoscience Frontiers 2012年第4期3卷 375-399页

作者： Linqi Xia Zuchun Xia Xueyi Xu Xiangmin Li Zhongping Ma Xi＇an Institute of Geology and mineral resources China Geological Survey Xi＇an Shaanxi 710054 China

Early Cambrian and Mid--Late Neoproterozoic volcanic rocks in China are widespread on several Precambrian continental blocks, which had aggregated to form part of the Rodinia supercon- tinent by ca. 900 Ma. On the basis of petrogeochemical data, the basic lavas can be classified into two major magma types： HT （Ti/Y 〉 500） and LT （Ti/Y 〈 500） that can be further divided into HT1 （Nb/La 〉 0.85） and HT2 （Nb/La ≤ 0.85）, and LT1 （Nb/La 〉 0.85） and LT2 （Nb/La ≤ 0.85） subtypes, respectively. The geochemical variation of the HT2 and LT2 lavas can be accounted for by lithospheric contamination of asthenosphere- （or plume-） derived magmas, whereas the parental magmas of the HT1 and LT1 lavas did not undergo, during their ascent, pronounced lithospheric contamination. These volcanics exhibit at least three characteristics：（1） most have a compositional bimodality; （2） they were formed in an intracontinental rift setting; and （3） they are genetically linked with mantle plumes or a mantle surperplume. This rift-related volcanism at end of the Mid-- Neoproterozoic and Early Cambrian coincided temporally with the separation between Australia-- East Antarctica, South China and Laurentia and between Australia and Tarim, respectively.

关键词： Neoproterozoic Bimodal volcanism Continental rift Mantle plume Rodinia supercontinent China

Gas Sources of Natural Gas Hydrates in the Shenhu Drilling Area, South China Sea: Geochemical Evidence and geological Analysis

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Acta Geologica Sinica(English Edition) 2013年第3期87卷 767-776页

作者： ZHU Youhai HUANG Xia FU Shaoying SU Pibo Oil & Gas survey China Geological Survey Institute of mineral resources Chinese Academy of Geological Sciences Guangzhou Marine geological survey

The Shenhu gas hydrate drilling area is located in the central Baiyun sag, Zhu I! depression, Pearl River Mouth basin, northern South China Sea. The gas compositions contained in the hydrate-bearing zones is dominated by methane with content up to 99.89% and 99.91%. The carbon isotope of the methane （δ^13C1） are -56.7%0. and -60.9%0, and its hydrogen isotope （δD） are -199%0 and -180%0, respectively, indicating the methane from the microbial reduction of CO2. Based on the data of measured seafloor temperature and geothermal gradient, the gas formed hydrate reservoirs are from depths 24-1699 m below the seafloor, and main gas-generation zone is present at the depth interval of 416-1165 m. Gas-bearing zones include the Hanjiang Formation, Yuehai Formation, Wanshan Formation and Quaternary sediments. We infer that the microbial gas migrated laterally or vertically along faults （especially interlayer faults）, slump structures, small-scale diapiric structures, regional sand beds and sedimentary boundaries to the hydrate stability zone, and formed natural gas hydrates in the upper Yuehai Formation and lower Wanshan Formation, probably with contribution of a little thermogenic gas from the deep sedments during this process.

关键词： natural gas hydrate methane microbial gas gas source migration South China Sea

Phanerozoic Paleomagnetism Characteristics of the Qomolangma Area in Tibet

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Acta Geologica Sinica(English Edition) 2013年第2期87卷 517-527页

作者： ZOU Guangfu PAN Zhongxi ZHUANG Zhonghai ZHU Tongxing LI Jianzhong FENG Xintao Chengdu Institute of Geology and mineral resources China Geological Survey

This paper conducts systematic test research on the 2920 paleomagnetic directional samples taken from Ordovician-Paleogene sedimentary formation in the north slope of Qomolangma in south of Tibet and obtains the primary remanent magnetization component and counts the new data of paleomagnetism the times. Based on the characteristic remanent magnetization component, it calculates the geomagnetic pole position and latitude value of Himalaya block in Ordovician- Paleogene. According to the new data of paleomagnetism, it draws the palaeomagnetic polar wander curve and palaeolatitude change curve of the north slope of Qomolangma in Ordovician-Paleogene. It also makes a preliminary discussion to the structure evolution history and relative movement of Himalaya bloc. The research results show that many clockwise rotation movements had occurred to the Himalaya block in northern slope of Qomolangmain the process of northward drifting in the phanerozoic eon. In Ordovician-late Cretaceous, there the movement of about 20.0~ clockwise rotation occurred in the process of northward drifting. However, 0.4° counterclockwise rotation occurred from the end of late Devonian epoch to the beginning of early carboniferous epoch; 6.0° and 8.0° counterclockwise rotation occurred in carboniferous period and early Triassic epoch respectively, which might be related with the tension crack of continental rift valley from late Devonian period to the beginning of early carboniferous epoch, carboniferous period and early Triassic epoch. From the Eocene epoch to Pliocene epoch, the Himalaya block generated about 28.0° clockwise while drifting northward with a relatively rapid speed. This was the result that since the Eocene epoch, due to the continuous expansion of mid-ocean ridge of the India Ocean, the neo-Tethys with the Yarlung Zangbo River as the main ocean basin closed to form orogenic movement and the strong continent-continent collision orogenic movement of the east and west Himalayas gener

关键词： paleomagnetic Phanerozoic tectonic movement the Qomolongma area Tibet

First Discovery of Gold Ore Bodies in the Lieryu Formation of the Liaohe Group in the Liaodong Area, China

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Acta Geologica Sinica(English Edition) 2017年第6期91卷 2342-2343页

作者： ZHANG Peng SHAO Jun LI Dongtao ZHAO Yan KOU Linlin BI Zhongwei Shenyang Institute of Geology and mineral resources Shenyang Center of geological SurveyChina Geological Survey

Objective Numerous large deposits magnesite, and talc are Liaodong area, within of lead-zinc, gold, boron, distributed throughout the different layers of the Paleoproterozoic Liaohe Group. The Liaohe Group comprises five formations as follows （from bottom to top）. The Langzishan Formation consists of volcaniclastic rocks containing copper, cobalt, and iron deposits. The Lieryu Formation is a set of volcanic sedimentary facies accompanied by small amounts of continental-margin mixed volcanic sedimentary rocks containing boron and magnetite deposits. The Gaojiayu Formation consists of carbonaceous clay-bearing carbonate rocks and contains the most important graphite deposit. The Dashiqao Formation consists of carbonate rocks containing lead-zinc and magnesite deposits. The Gaixian Formation comprises clastic and volcaniclastic rocks, and contains the most important gold deposit. Historically, gold prospecting has focused on the Gaixian Formation; however, gold ore bodies have been discovered during iron ore mining in the Lieryu Formation （Dayinggou area）, indicating possible existence of larger gold deposits in the area.

关键词： First Discovery of Gold Formation of the Liaohe

Middle Devonian-Tournaisian rocks and biota on Hainan Island,South China

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Science China Earth Sciences 2013年第11期56卷 1934-1941页

作者： ZHANG RenJie YAO HuaZhou WANG JianXiong TU Bing Wuhan Institute of Geology and mineral resources China Geological Survey

On the basis of new paleontological data,the sequence and distributions of the Middle Devonian-Tournaisian rocks on Hainan Island have been sorted out for the first *** Devonian rocks include the Middle Devonian Jinbo Formation and the Upper Devonian Changjiang Formation,which are distributed in northwestern Hainan *** Jinbo Formation is represented by631 m of littoral facies deposits,and was intruded by the Yanshanian granite in the *** presence of chitinozoans Eisenackitina caster,Funsochitina pilosa,and Lagenochitina amottensis indicates the Givetian in *** Changjiang Formation is made up of 140 m of neritic facies rocks,and contains the Famennian conodonts Palmatolepis gracilis sigmoidalis,Polygnathus germanus,and corals Cystophrentis *** Devonian-Tournaisian transition beds,the lower part of the Jishi Formation,are composed of 61–129 m sandstone and siltstone,with gastropods Euomphalus *** brachiopods,and marked by conglomerate with the underlying Devonian *** middle-upper part of the Tournaisian Jishi Formation consists of 100–251 m clastic and carbonate rocks,containing abundant corals Pseudoularinia irregularis,conodonts Siphonodella isosticha,trilobites Weberiphillipsia linguiformis,and *** the basis of the occurrence of Xinanosprifer flabellum and Homotoma sp.,the Nanhao Formation in southern Hainan Island is now regarded as the Lower Silurian,instead of the previously designated Lower *** is confirmed that no Carboniferous rocks occurred in the area south to the Gancheng-Wanning Fault.

关键词： Devonian-Tournaisian rocks biota Hainan Island China

Geochemical Constrains on Petrogenesis and Tectonic Setting of Volcanic Rocks from the Baimianxia and Sanwan Formations in the Northern Margin of the Yangtze Plate

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Acta Geologica Sinica(English Edition) 2011年第6期85卷 1336-1350页

作者： XU Xuey CHEN Junlu1 LI Xiangmin MA Zhongping WANG Hongliang LI Ping LI Ting Xian Institute of Geology and mineral resources China Geological Survey Xi ＇an Shaanxi 710054 China Changan University Xi＇an Shaanxi 710069 China

On the basis of petrogeochemical data, the volcanic lavas of the Baimianxia Formation can be classified into two units： high TiO2 and low TiO2. The TiO2 concentration of the former is generally higher than 1%, which occurs in the lower part with high-grade metamorphism, but the latter is less than 1% and crops out in the upper part with low-grade metamorphism. The high-TiO2 unit is dominated by tholeiitic lavas showing high rare earth element （REE） contents （~REE = 83.4-180.8 pg/ g）, high light/heavy REE （LREE/HREE） ratios （LREE/HREE=2.17-5.85） and weak negative Eu anomaly （Eu=0.79-1.01）. Its trace element patterns display weak Nb-Ta anomalies with respect to Th, K, La, Ce, showing within-plate basalt affinities. In contrast, the low-TiO2 unit is characterized by low REE contents, low LREE/HREE ratios, and pronounced Nb-Ta anomalies, indicating typical arc or continental arc signature. Chondrite-normalized REE patterns of basalts and andesites from the Sanwan Formation are flat or LREE depletion, which is very similar to normal mid-oceanic basalt. Therefore, we suggest that these lavas should be formed in a back-arc basin setting. Sr-Nd isotopic data of the basalt in the lower part suggest that the rocks would have been formed in ~1144 Ma. Based on the geochemical and isotopic features of the basalts, we suggest that these rocks in the low part of the Baimianxia Formation should originate from an asthenospheric oceanic-island basalt-like mantle source, which may be produced by partial melting of garnet lherzolite, and significantly underwent fractional crystallization and crustal or lithospheric mantle contamination en route to the surface. However, laser ablation inductively coupled plasma mass spectrometry zircon U-Pb dating of the basalt sample from the upper part of the Baimianxia Formation gives a 437 Ma, indicating a Early Paleozoic age. The geochemical analysis in this paper suggests that they may originate from an arc or continental arc in response to aqueou

关键词： petrogenesis petrogeochemistry U-Pb dating Baimianxia and Sanwan Formations