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U-Pb Zircon Ages and geochemistry.of the Metasedimentary Rocks from the Foping Area in the South Qinling Belt:Evidence for Early Devonian Amalgamation between North China and South China Blocks

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Journal of Earth Science 2023年第4期34卷 1112-1127页

作者： Ruiying Zhang Wenhao Ao Yan Zhao State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi􀆳an 710069China

The provenance and tectonic implications of Late Paleozoic sedimentary rocks in the South Qinling Belt(SQB) provide important clues for understanding the timing and mechanism of the collision between North China Block(NCB) and South China Block(SCB).Here we report new LAICP-MS zircon U-Pb ages and geochemical composition of metasedimentary rocks from the Foping area in the SQB.The results indicate that the depositional age of the Wenquan Group can be limited to the Early Devonian by the youngest U-Pb age of 398 Ma,whereas those of the quartz schist from the Changjiaoba Group could be constrained after the Carboniferous by the youngest206Pb/238U peak age of 306 Ma.Therefore,much of the previously-assumed “Neoarchaean or Paleoproterozoic” strata,including the Wenquan and Changjiaoba groups,were actually deposited in the Late Paleozoic.Based on analysis and comparison of the detrital zircon ages of the Devonian tectonic units in the SQB,we found that most prominent peak ages of detrital zircons from metasedimentary rocks in the Foping area shared similar characteristics with others.They mainly derived from the North Qinling Belt and South Qinling Belt-Yangtze Block,with a minor source probably from the North China Block,implying that the Shangdan Ocean between NCB and SCB had closed in the Early Devonian.Combined with regional geological background and geochemical data,we inferred that these Devonian strata formed in the foreland basin after the amalgamation of the North China Block and South China Block.

关键词： detrital zircon geochronology geochemistry Devonian sedimentation South Qinling belt forelandbasin geochemistry.

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Petrology, geochemistry.and Geochronology of Gabbros from the Zhongcang Ophiolitic Mélange, Central Tibet: Implications for an Intra-Oceanic Subduction Zone within the Neo-Tethys Ocean

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Journal of Earth Science 2014年第2期25卷 224-240页

作者： Mengjing Xu Cai Li Wei Xu Chaoming Xie Peiyuan Hu Ming Wang College of Earth Science Jilin University

In order to investigate the evolution of Shiquanhe-Yongzhu-Jiali ophiolitic melange belt, the gabbros from new discovered Zhongcang ophiolitic melange are studied through petrology, whole-rock geochemistry. zircon U-Pb dating and Lu-Hf isotope. The gabbros investigated in this paper contain cumulate gabbro and gabbro dike, and they have undergone greenschist-amphibolite facies metamorphism. The chondrite normalized rare earth element （REE） patterns of most of these rocks show flat types with slightly light REE （LREE） depletion and the N-MORB normalized incompatible elements diagrams indicate depletion in high field strength elements （HFSE）（Nb, Ta） and enrichment in large ion lithophile elements （LILE）. These gabbros have island arc and mid-ocean ridge basalt af- finities, suggesting that they were originated in an oceanic back arc basin. Whole rock geochemistry.and high positive εNd（t） values show that these gabbros were derived from -30% partial melting of a spinel lherzolite mantle, which was enriched by interaction with slab-derived fluids and melts from sediment. U-Pb analyses of zircons from cumulate gabbro yield a weighted mean age of 114.3±1.4 Ma. Based on our data and previous studies, we propose that an intra-oceanic subduction system and back arc basin operated in the Neo-Tethy Ocean of central Tibet during Middle Jurassic and Early Creta- ceous, resembling modern active intra-oceanic subduction systems in the western Pacific.

关键词： Tibet Zhongcang ophiolitic melange gabbro Shiquanhe-Yongzhu-Jiali ophiolitic me- lange belt geochemistry.

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K-Ar Ages and geochemistry.of the Mariana Trough Basalts

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Chinese Science Bulletin 1994年第22期39卷 1900-1904页

作者：穆治国张成陈成业刘驰黄宝岭苗国均吴士迎 Department of Geology Peking University Beijing 100871 PRC First Institute of Oceanography SOA Qingdao 266003 PRC

Studies on the Mariana Trough basalts began in the early 1970s, and during the past two decades, they are getting deeper and deeper with the Deep Sea Drilling Project devoted to the back-arc and the trough.From the ea... 详细信息

关键词： Mariana Trough oceanic tholeiite K-Ar age geochemistry.

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PROTEROZOIC INTRACONTINENTAL RIFTING OF THE QINLING OROGENIC BELT: EVIDENCE FROM THE geochemistry.OF SEDIMENTARY ROCKS

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Chinese Science Bulletin 1991年第11期36卷 920-923页

作者：高山张本仁谢千里郭孝明 Department of geochemistry China University of Geosciences Wuhan 430074 PRC

Ⅰ. INTRODUCTIONThe Proterozoic tectonic nature of the Qinling Orogenic Belt has fundamental importance in understanding the evolutionary history of the Qinling Belt and the North China and Yangtze (South China) cratons, where the Qinling Group plays a crucial role. Although there is a consensus that this group was mostly of the early Proterozoic age, much controversy still remains on its tectonic environment of formation.

关键词： Qinling Orogenic Belt Proterozoic intracontinental rifting graywacke geochemistry.

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Crustal Signature of δ^(13)C and Nitrogen Content in Microdiamonds from Erzgebirge, Germany: Ion Microprobe Studies

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Journal of Earth Science 2010年第5期21卷 623-634页

作者： Larissa F Dobrzhinetskaya Harry W Green II Naoto Takahata Yuji Sano Korato Shirai Department of Earth Sciences University of California at Riverside Riverside 92521 USA Division of Ocean-Earth Systems Atmosphere and Ocean Research Institute University of Tokyo Kashiwanoha Chiba 277-8564 Japan

The study of δ13CCpDB （Pee Dee Belemnite） and nitrogen contents in 1 to 5-pm-diameter microdinmonds included in garnets from the qnartz-feldspathic gneisses （Erzgehirge, Germany） was performed in situ with the Nano-scale Secondary Ion Mass Spectrometer. The results revealed that there were two stages of diamond crystallization from a C-O-H supeeritical fluid rich in biogenic carbon and diverse minor elements of crustal origin. The δ13CCpDB Of the Erzgebirge diamond of the first stage falls in the range -17‰ to 19‰, with an average value of -17.8‰; the average content of nitrogen is 820 ppm. Diamonds of the second stage are characterized by δ13CPDB=-21.5‰ to -25.5‰, with an average value of -23.24‰; the average nitrogen content is non-homogeneously scattered from 740 ppm to 3 370 ppm among 6 diamonds situated in garnets within the same polished rock slide. Both diamond of the first stage and diamond of the second stage carbon reservoirs belong to biogenic matter, therefore confirming deep subduction of the continental crust sediments and their subsequent exhumation during the Variscan orogeny.

关键词： metamorphic diamond carbon isotope nitrogen content geochemistry.

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Major element,trace element,and Sr,Nd and Pb iso-tope studies of Cenozoic basalts from the South China Sea

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Science China Earth Sciences 2008年第4期51卷 550-566页

作者： YAN QuanShu SHI XueFa WANG KunShan BU WenRui XIAO Long Key Lab of Marine Sedimentary and Environment Geology The First Institute of OceanographyState Oceanic AdministrationQingdao 266061China Institute of Oceanology Chinese Academy of SciencesQingdao 26607China Faculty of Earth Sciences China University of GeosciencesWuhan 430074China

The whole rock K-Ar ages of basalts from the South China Sea basin vary from 3.8 to 7.9 Ma, which suggest that intra-plate volcanism after the cessation of spreading of the South China Sea (SCS) is comparable to that in adjacent regions around the SCS, i.e., Leiqiong Peninsula, northern margin of the SCS, Indochina block, and so on. Based on detailed petrographic studies, we selected many fresh ba-saltic rocks and measured their major element, trace element, and Sr-Nd-Pb isotope compositions. Geochemical characteristics of major element and trace element show that these basaltic rocks belong to alkali basalt magma series, and are similar to OIB-type basalt. The extent of partial melting of mantle rock in source region is very low, and magma may experience crystallization differentiation and cu-mulation during the ascent to or storing in the high-level magma chamber. Sr-Nd-Pb isotopic data of these basaltic rocks imply an inhomogeneous mantle below the South China Sea. The nature of magma origin has a two end-member mixing model, one is EM2 (Enriched Mantle 2) which may be originated from mantle plume, the other is DMM (Depleted MORB Mantle). Pb isotopic characteristics show the Dupal anomaly in the South China Sea, and combined with newly found Dupal anomaly at Gakkel ridge in Arctic Ocean, this implies that Dupal anomaly is not only limited to South Hemisphere. In variation diagrams among Sr, Nd and Pb, the origin nature of mantle below the SCS is similar to those below Leiqiong peninsula, northern margin of the SCS and Indochina peninsula, and is different from those below north and northeast China. This study provides geochemical constraints on Hainan mantle plume.

关键词： Cenozoic alkali basalt Dupal anomaly Hainan mantle plume the South China Sea geochemistry.

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Differential Geochemical Features of Clinopyroxene from the Floodplain Sediments in Yangtze and Hanjiang Rivers and Its Implication for Detrital Source Identification

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Journal of Earth Science 2014年第4期25卷 638-647页

作者： Jian Yang Chang'an Li Yufen Zhang N'dji dit Jacques Dembele Faculty of Earth Sciences China University of Geosciences Key Laboratory of Biogeology and Envirnmental Geology of Ministry of Educations China University of Geosciences Institute of Geophysics and Geomatics China University of Geosciences

The evolution history of the Yangtze River attracted increasing attention in recent years. Comparison of the properties of the floodplain sediments between the upper and lower reaches of the Three Gorges is of significance to identify the material detrital sources for the Yangtze River Basin. Clinopyroxene （Cpx） is the typical mineral widely distributed in the sediments of the Yangtze River Ba- sin. Cpx was extracted from the fine sediments with the grain size ranging from 0.063 to 0.125 mm in the upper and lower reaches of the Three Gorges. The sediments, from which the Cpx was extracted, were taken from the floodplains of the catchments of both the Yangtze River and the Hanjiang River, as well as from the surface of the Zhoulao Core drilled in the center of the Jianghan Basin where the two rivers flow through. geochemistry.of these Cpx was investigated, concerning the contents of major elements measured by electron probe microanalysis （EPMA） and the contents of trace elements analyzed by laser ablation inductively coupled plasma-mass spectrometry （LA-ICP-MS）. The Cpx in the Yangtze River contains titaniferous augite which is sourced from the Panzhihua-Xichang region in South Sichuan Province, whereas the Cpx in the Hanjiang River is mainly from the surroundings without any titanif- erous augite. The REE analysis infers that the titaniferous augite is the diagnostic mineral of the upper Yangtze River, and thus could be used as a tracer mineral to identify the detrital sources for the sedi- ments formed during the evolution of the Yangtze River. The Cpx from the surface sediments of the Jianghan Plain （Zhoulao Core） shows comparable geochemical nature with that of the Yangtze River, but is different in geochemistry.from that of the Hanjiang River, implying that the modern sediments in the Jianghan Plain are mainly sourced from the upper Yangtze River.

关键词： provenance Yangtze River Hanjiang River clinopyroxene EPMA LA-ICP-MS geochemistry.

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Physicochemical Control of the Early Permian Xiangshan Fe-Ti Oxide Deposit in Eastern Tianshan(Xinjiang),NW China

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Journal of Earth Science 2018年第3期29卷 520-536页

作者： Yu Shi Yuwang Wang Jingbin Wang Lutong Zhao Hongjing Xie Lingli Long Tao Zou Dedong Li Guochao Zhou Beijing Institute of Geology for Mineral Resources Beoing 100012China School of Earth Sciences and Resources China University of GeosciencesBeijing 100083China Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming 650093China

The Xiangshan mafic-ultramafic complex is one of the major Early Permian maficultramafic intrusions in eastern Tianshan （Xinjiang, NW China）, and consists of two major intrusive phases. The first intrusive phase is mainly gabbroic rocks hosting ilmenite mineralization, while the second intrusive phase is mainly lherzoilite associated with Ni-Cu sulfide mineralization. The Xiangshan ilmenite orebodies hosted in the Fe-Ti oxide-bearing gabbro occur along the contact between hornblende gabbros and leucogabbros. The hornblende gabbros and Fe-Ti oxide rich gabbros at Xiangshan are newly dated to be Early Permian （280.1 and 279.2 Ma, respectively）. Major and trace element compositions of zircons and whole rocks from Xiangshan hornblende gabbro and Fe-Ti oxide gabbro have been measured by in situ excimer laser ablation ICP-MS. Zircon Ce^4＋/Ce^3＋ ratios based on lattice-strain model and Ti-in-zircon temperatures of hornblende gabbro and Fe-Ti oxide gabbro of the Xiangshan complex are calculated to evaluate the physicochemical variations during the ilmenite mineralization. Whole-rock geochemistry.and zircon trace element geochemistry.suggest that Fe-Ti oxide gabbros were formed from a basaltic parent magma which had undergone a transfromation from being H2O-rich to H2O-poor. During the magmatic evolution, primitive, HEO-poor basaltic melts may have been replenished into the system, increasing its solidus temperature and decreasing its oxygen fugacity and H2O contents. This may have supperessed the Ti-rich poikilitic hornblende fractionation and promoted the plagioclase fractionation, which consequently concentrated the ore-forming components in the residual melts and generated the ilmenite mineralization.

关键词： eastern Tianshan magmatic Fe-Ti oxide deposits gabbros layered intrusion zircon U-Pb age geochemistry.

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Genesis and organic geochemical characteristics of the carbonaceous rock stratabound gold deposits, South China

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Science China Earth Sciences 2000年第5期43卷 507-520页

作者：胡凯翟建平刘英俊王鹤年张景荣贾蓉芬 Department of Earth Sciences State Key Laboratory for Mineral Deposit Research Nanjing University Nanjing 210093 China Guangzhou Institute of geochemistry Chinese Academy of Sciences Guangzhou 510640 China

The organic matter of three different chronological major carbonaceous rock gold-bearing formations of South China (Middle Proterozoic Shangqiaoshan group of northeastern Jiangxi, Lower Cambrian Shuikou group of northern Guangxi and Devonian Shetianqiao group of eastern Hunan) and related carbonaceous stratabound gold deposits such as Jinshan, Longshui and Shixia deposits, respectively, has been characterized by organic geochemical techniques. These organic geochemical results show that the average total organic carbon (TOC) content of the three chronological carbonaceous rock gold-bearing formations of South China ranges from 0.15% to 1.56%. The thermal maturity of the organic matter of host rocks in the three gold-bearing formations is high. The micro-component of the organic matter of the host rocks consists primarily of solid bitumen and graphite. The organic carbon and gold of the host rocks appear to syndeposit in situ during the formation of the gold-bearing formations. The organic carbon

关键词： carbonaceous rock formation stratabound gold deposit organic matter kerogen organic geochemistry.

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Migration and accumulation of natural gas in Kela-2 gas field

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Chinese Science Bulletin 2002年第S1期47卷 107-112页

作者： WANG Zhaoming WANG Tingdong XIAO Zhongyao XU Zhiming LI Mei LIN Feng Research Institute of Exploration and Development Tarim Oil Field Sub-CompanyPetroChinaKorla 841000China Southwest Petroleum Institute Nanchong 637001China

With the guidance of petroleum system theory,the dynamic filling history of natural gas in the Kela-2 gasfield is analyzed by using a large suite of oil and gas geo-chemistry evidence in combination with the tectonic evolu-tion history and reservoir evolution history. It concludes thatthe Kela-2 gas field was formed by capturing the gas gener-ated during the main gas generation period, while the latekerogen cracking gas contributed a little to the gas field. Itsuggests that the gas generated during the main gas genera-tion accumulated in the early-formed wide-gentle anticline,which is the necessary condition for natural gas to re-migrateand enrich late to form the large-scale gas reservoir. Thenewest research shows that the filling history of gas in theDabei-1, Yinan-2, Tuziluoke and Dina-2 gas fields was re-lated with the natural gas accumulation in the early wide-gentle anticline as well as late re-migration and enrichmentof natural gas.

关键词： Kela-2 gas field migration and accumulation of natural gas carbon isotope gas reservoir geochemistry.

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