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Hydrothermal alteration of dolostones in the Lower Ordovician,Tarim Basin,NW China:Multiple constraints from petrology,isotope geochemistry and fluid inclusion microthermometry

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Hydrothermal alteration of dolostones in the Lower Ordovicia...

Geochronology and petrogenesis of the mafic dykes from the Purang ophiolite:Implications for evolution of the western Yarlung-Tsangpo suture zone,southwestern Tibet

中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Shaofeng Dong Daizhao Chen Hairuo Qing Xiqiang Zhou Dan Wang Zenghui Guo Maosheng Jiang Yixiong Qian Key Laboratory of Petroleum Resources Research Institute of Geology and GeophysicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences Department of Geology University of ReginaReginaSKCanada S4S0A2 Research Institute of China National Offshore Oil Corporation

Massive dolostones pervasively occur in the Lower Paleozoic strata in Tarim Basin,NW *** study focuses on the hydrothermally-altered dolostones in the Lower Ordovician at Sancha,Bachu County where the hydrothermally-altered dolostones,marbles and diabase intrusions co-occur within a largescale, NW trending strike-slip fault *** this zone,the intrusive diabases mostly occur along the master border faults to the east and west,*** limestones that got in contact with the intrusions commonly were marbleized and the antecedent dolostones were subject to intense hydrothermal alteration,particularly along fractured *** on field investigations and petrographic examinations on the hydrothermally-altered dolostones,five distinctive fabrics of matrix and cement dolomites are *** episodes of vein-filling calcites postdate the hydrothermallyprecipitated saddle *** isotopic geochemistry(C,O and Sr) and fluid inclusion micro thermometry suggest that dolomite recrystallization and precipitation were associated with the hydrothermal activity induced by fracturing/faulting and intrusive *** SIMS U-Pb isotopic dating of zircon grains from the diabases yields an age of 290.5±2.9 Ma in the Early Permian, which reconciles the relative timing revealed by the paragenetic *** magmatic emplacement was thus linked to the large igneous province(LIP) of Early Permian in Tarim *** this case,the widespread magmatic activities could have caused the thermal anomaly and fracturing in the strata that were penetrated by the intrusions,enhancing the thermal diffusion and hydrothermal fluid migration (although minor volumes of thermal fluids from the basic magmas) through the fracture/fault systems, thereby resulting in contact metamorphism(or marbleization),recrystallization of matrix dolomites and dolomite precipitation commonly in primary dolostone *** study provides a useful analogue to unders

关键词： Tarim Basin Lower Ordovician Tectono-magmatism isotope geochemistry U-Pb isotope dating Hydrothermally-altered dolostone

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Geoscience Frontiers 2020年第1期11卷 277-292页

作者： Fahui Xiong Yuanku Meng Jingsui Yang Zhao Liu Xiangzhen Xu Alireza Eslami Ran Zhang Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals College of Earth Science and EngineeringShandong University of Science and TechnologyQingdao 266590China Center for Advanced Research on the Mantle(CARMA) Key Laboratory of Deep-Earth Dynamics of Ministry of Land and ResourcesInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China Institute of Mineral Resources Chinese Academy of Geological SciencesBeijing 100037China School of Geology College of ScienceUniversity of TehranTehran ***Iran

The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian *** the ophiolitic complexes,the Purang ophiolite is the biggest massif in the IYSZ,and many studies have been conducted on this ***,previous studies have mainly focused on harzburgite,clinopyroxenite and *** observations show that mafic dykes were emplaced within the Purang ***,petrogenetic evolutions of those mafic dykes are poorly *** this study,we present new LA-ICP-MS zircon U-Pb dating results,whole-rock geochemistry and Sr-Nd-Hf isotope analyses for microgabbro,gabbro and dolerite dykes from the Purang ophiolite of the southwestern IYSZ,*** samples yielded zircon U-Pb ages of144.2±2.1 Ma.127.9±2.3 Ma and 126.5±0.42 Ma,suggesting two different phases of magmatic activities ***-rock geochemical results suggest that the gabbro samples show alkaline features marked by enrichments of light rare earth elements(LREE)and large-ion lithophile elements(LILE),as well as Nb-Ta elements,suggesting an oceanic island basalt-like(OIB-like)geochemical ***,the dolerite and microgabbro samples demonstrate sub-alkaline characteristics with normal mid-oceanic ridge basalt-like(N-MORB-like)geochemical *** distinct mafic dykes show significant Rb element *** geochemical data and Sr-Nd-Hf isotopic features suggest that the microgabbro and gabbro rocks were derived from a depleted mantle that had been metasomatized by partial melts of sediments and enriched slab-derived *** dolerite was also originated from a depleted mantle marked by significantly depleted Sr-Nd-Hf compositions,which was not influenced by enriched slab-derived fluids and sediments contamination during subsequent *** isotope and geochemical data and tectonic diagrams sugges

关键词： isotope geochemistry Mafic rocks Purang ophiolite Yarlung Tsangpo suture zone

Geochemical and Nd-Sr Isotopic Compositions of Hypabyssal Adakites in the Torud-Ahmad Abad Magmatic Belt,Northern Central Iran Zone:Analysis of Petrogenesis and Geodynamic Implications

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Journal of Earth Science 2021年第6期32卷 1428-1444页

作者： Fazilat Yousefi Ryan D.Mills Mahmoud Sadeghian David R.Lentz Christina Wanhainen Habibollah Ghasemi Laicheng Miao Department of Earth Sciences University of New BrunswickFrederictonCanada Department of Geological Sciences University of North Carolina at Chapel HillChapel HillUSA Faculty of Earth Sciences Shahrood University of TechnologyShahroodIran Department of Civil Environmental and Natural Resources EngineeringLulea University of TechnologyLuleaSweden Institute of Geology and Geophysics Chinese Academy of SciencesBeijing100029China

Eocene intermediate to felsic subvolcanic rocks of the Torud-Ahmad Abad magmatic belt(TAMB),in the northern part of the Central Iran zone,are exposed between the Torud and Ahmad Abad regions in South-Southeast *** igneous rocks include hypabyssal dacite,trachyte,andesite,trachy-andesite,and basaltic andesite;they are mainly composed of phenocrysts and microcrystalline groundmass of pyroxene,amphibole,and plagioclase,with minor biotite and titanomagnetite;they form domal structures(plugs and stocks),dikes,and sills that intruded into Neoproterozoic to cogenetic Eocene volcano-sedimentary *** on isotopic analysis of these intermediate to acidic rocks,initial ratios of^(143)Nd/^(144)Nd range from 0.512775 to 0.512893 and initial ratios of^(87)Sr/^(86)Sr range from 0.703746 to 0.705314,with quite positiveε_(Nd(i))values of+3.69 to+*** are enriched in light rare earth elements and large ion lithophile elements and depleted in heavy rare earth elements and high-field strength elements,the SiO_(2) content is(52-62)wt.%,and Na_(2)O content>3 wt.%,Al_(2)O_(3) content>16 wt.%,Yb<1.8 ppm,and Y<18 *** geological,geochemical,and Sr and Nd isotopic data are consistent with adakitic signatures originating by partial melting of the subducted Neo-Tethys oceanic slab(Sabzevar branch)and lithospheric suprasubduction zone *** mantle signatures typifying the rapidly emplaced adakitic rocks(slab(high-silica adakite)and suprasubduction zone(low-silica adakite)melts)together with their locally voluminous extent are evidences that support a locally extensional geodynamic setting;and the evidence is consistent with an evolution to local transpression in the Late Eocene in this convergent margin are environment to rifting(basalts to adakites)towards submarine conditions in the Neogene.

关键词： isotope geochemistry adakite rocks Central Iran zone Shahrood Iran

Genesis of the Maoling gold deposit in the Liaodong Peninsula:Constraints from a combined fluid inclusion,C-H-O-S-Pb-He-Ar isotopic and geochronological studies

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Geoscience Frontiers 2022年第4期13卷 11-33页

作者： Peng Zhang Linlin Kou Yan Zhao Deming Sha Shenyang Geological Survey Center China Geological SurveyShenyang 110034China

The large tonnage Maoling gold deposit(25 t@3.2 g/t)is located in the southwest Liaodong Peninsula,North China *** deposit is hosted in the Paleoproterozoic metamorphic *** stages of mineralization were identified in the deposit:(stageⅠ)quartz-arsenopyrite±pyrite,(stageⅡ)quartz-goldarsenopyrite-pyrrhotite,(stageⅢ)quartz-gold-polymetallic sulfide,and(stageⅣ)*** this paper,we present fluid inclusion,C-H-O-S-Pb-He-Ar isotope data,zircon U-Pb,and gold-bearing sulfide(*** and pyrrhotite)Rb-Sr age of the Maoling gold deposit to constrain its genesis and ore-forming *** types of fluid inclusions were distinguished in quartzbearing veins,including liquid-rich two-phase(WL type),gas-rich two-phase(GL type),and daughter mineral-bearing fluid inclusions(S type).Fluid inclusions data show that the homogenization at temperatures 197 to 372°C for stageⅠ,126 to 319°C for stageⅡ,119 to 189°C for stageⅢ,and 115 to 183°C for stageⅣ,with corresponding salinities of 3.7 to 22.6 wt.%,4.7 to 23.2 wt.%,5.3 to 23.2 wt.%,and 1.7 to14.9 wt.%Na Cl equiv.,*** boiling was the critical factor controlling the gold and associated sulfide precipitation at *** and oxygen stable isotopic analyses for quartz yielded δ^(18)O=-5.0‰ to 9.8‰ and δD=-133.5‰ to-77.0‰.Carbon stable isotopic analyses for calcite and ankerite yielded δ^(13)C=-2.3‰to-1.2‰ and O=7.9‰ to 14.1‰.The C-H-O isotope data show that the oreforming fluids were originated from magmatic water with meteoric water input during *** inclusions in arsenopyrite have ^(3)He/^(4)He ratios of 0.002 Ra to 0.054 Ra,and ^(40)Ar/^(36)Ar rations of 1225 to 3930,indicating that the ore-forming fluids were dominantly derived from crustal sources almost no mantle *** isotopic values of Maoling fine-grained granite range from6.‰1 to 9.8‰,with a mean of 7.7‰,δ^(34)S values of arsenopyrite from the mineralized phyllite(host rock)range fr

关键词： Geochronology Fluid inclusions isotope geochemistry Maoling gold deposit Liaodong Peninsula

Depositional age and tectonic environment of the Gouap banded iron formations from the Nyong group,SW Cameroon:Insights from isotopic,geochemical and geochronological studies of drillcore samples

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Geoscience Frontiers 2021年第2期12卷 549-572页

作者： Landry Soh Tamehe Chongtao Wei Sylvestre Ganno Carlos Alberto Rosiere Jean Paul Nzenti Chesther Gatse Ebotehouna Guanwen Lu Key Laboratory of CBM Resources and Reservoir Formation Process Chinese Ministry of EducationChina University of Mining and TechnologyXuzhouJiangsu221116China Department of Earth Sciences University of Yaounde IP.O.Box 812YaoundeCameroon Department of Geology Universidade Federal de Minas Gerais31270-901Belo HorizonteMinas GeraisBrazil School of Civil and Environmental Engineering University of Science and Technology BeijingBeijing 100083China

The discovery of the Gouap banded iron formations(BIFs)-hosted iron mineralization in the northwestern of the Nyong Group(Ntem Complex)in southwestern Cameroon provides unique insights into the geology of this *** this contribution,we firstly report detailed study of geochemistry,isotopic and geochronology of well preserved samples of the Gouap BIFs collected from diamond *** Gouap BIFs consist mainly of amphibole BIFs and amphibole-pyrite BIFs characterized by dominant Fe_(2)O_(3)+SiO_(2)contents and variable contents of CaO,MgO and SO_(3),consistent with the presence of amphibole,chlorite,epidote and pyrite,formed during amphibolite facies metamorphism and overprinted hydrothermal *** amphibole–pyrite BIFs are typically enriched in trace and rare earth elements(REE)compared to the amphibole BIFs,suggesting the influence of detrital materials as well as secondary hydrothermal *** Post Archean Australian Shale(PAAS)-normalized REE–Y profiles of the Gouap BIFs display positive La,Eu anomalies,weak negative Ce anomalies,indicating a mixture of low-temperature hydrothermal fluids and relatively oxic conditions probably under relative shallow *** present here the first isotopic data of BIFs within the Ntem ***δ^(30)Si_(NBS28)values of the quartz from the Gouap BIFs vary from-1.5‰to-0.3‰and from-0.8‰to-0.9‰for the amphibole BIFs and amphibole–pyrite BIFs,*** quartz hasδ^(18)OV-SMOW values of 6.8‰–9.5‰(amphibole BIFs)and 9.2‰–10.6‰(amphibole–pyrite BIFs).The magnetite from the Gouap BIFs showsδ^(18)O values ranging from-3.5‰to-1.8‰and from-3‰to-1.7‰for the amphibole BIFs and amphibole–pyrite BIFs,***,the pyrite grains in the amphibole–pyrite BIFs displayδ34S values of 1.1‰–1.8‰.All isotopic data of the Gouap BIFs confirm that they might have precipitated from low-temperature hydrothermal fluids with detrital input distant from the volcanic *** to their geochemical and isotop

关键词： Gouap Banded iron formations isotope geochemistry Zircon geochronology Ryacian period Brasiliano-Congo orogeny

ESR Signal Intensity and Crystallinity of Quartz from Three Major Asian Dust Sources: Implication for Tracing the Provenances of Eolian Dust

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Journal of Groundwater Science and Engineering 2013年第3期1卷 53-67页

作者： Hong-yun Chen You-bin Sun Ryuji Tada Dominik Weiss Min Lin Institute of Hydrogeology and Environmental Geology Chinese Academy of Geological Sciences State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of Science Department of Earth and Planetary Science University of Tokyo Department of Earth Science and Engineering Imperial College London School of Earth Science Stanford University China Institute of Atomic Energy

We measured Electron Spin Resonance(ESR) signal intensity and Crystallinity Index(CI) of fine-(16 m) quartz in surface samples collected from the Taklimakan desert in western China, the Badain Juran, Tengger and Mu Us deserts in northern China, and the Gobi desert in southern Mongolia. The aim was to test if these two parameters can be used as the accurate provenance tracers of Asian dust. Coarse-grained quartz displays spatial variability of the ESR signal intensity within each desert and of the CI within the Taklimakan and the Mongolian Gobi deserts. Coarse-grained quartz derived from the Mongolian Gobi and northern China deserts can be differentiated from the Taklimakan desert using the ESR signal intensity. By contrast, variability of ESR signal intensity and CI of fine-grained quartz particles is distinct within the Taklimakan and the Mongolian Gobi deserts, but less significant in three deserts of northern China. Spatially, fine-grained dust originating from three major Asian dust sources(i.e., the Gobi-sandy deserts in western China, northern China and southern Mongolia) can be differentiated using the combination of the ESR and CI signals. Our results suggest that combination of the ESR and CI results can discriminate the sources of fine-grained dust better than coarse-grained dust, providing an effective approach to trace the provenance of fine-grained dust depositions on the land and in the ocean.

关键词： ESR signal intensity Crystallinity sources CHINESE LOESS PLATEAU BADAIN JARAN DESERT isotope geochemistry MINERAL AEROSOLS TIBETAN PLATEAU NORTH PACIFIC AEOLIAN DUST DEPOSITION ND EVOLUTION

A brief review of isotopically light Li-a feature of the enriched mantle?

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A brief review of isotopically light Li-a feature of the enr...

Early Carboniferous intra-oceanic arc and back-arc basin system in the West Junggar,NW China

中国科学院地质与地球物理研究所第十届(2010年度)学术年会

作者： Yan-Jie Tang~*,Hong-Fu Zhang and Ji-Feng Ying State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics, Chinese Academy of Sciences,Beijing,China

Lithium isotope geochemistry is increasingly being used to trace deep-earth processes, reflecting the observed large variation of Li isotope ratios in mantle-derived rocks, including peridotite xenoliths associated with ancient *** briefly review the Li isotopic compositions of major geochemical reservoirs,the assumed mechanisms of Li isotopic fractionation,and,in particular,the origins of isotopically light Li in mantle-derived rocks based on the latest developments in Li isotope *** of Li isotope data with existing Sr-Nd isotope ratios reflects the subduction-recycling of ancient oceanic crust and the reappearance of Li in volcanic *** circulation may play an important role in generating the isotopically light-Li component in the mantle-perhaps the enriched mantle end member defined by the Sr-Nd isotopic compositions of oceanic basalts.

关键词： lithium isotope geochemistry fractionation mechanisms peridotite xenoliths review of Li iso topic evolution

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Early Carboniferous intra-oceanic arc and back-arc basin sys...