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Carbon and Oxygen Stable Isotope Values and Microfossils at 41.4-4.5ka BP in Tai Co,Tibet,china,and Their Paleoclimatic Significance

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Acta Geologica Sinica(English Edition) 2011年第5期85卷 1036-1050+1052-1056+1051页

作者： ZHENG Mianping~(1,2,*),LIU Junying~(1,3.,MA Zhibang~(1,4),WANG Hailei~(1,2) and MA Nina~(1,2) 1 MLR Key Laboratory of Saline Lake Resources and Environment,institute of Mineral Resources,CAGS, beijing 100037,china 2 Research and Development Center for Saline Lakes and Epithermal Deposits,{3. Academy of geological sciences,beijing 100037,china 3.institute of geology,{3. Academy of geological sciences,beijing 100037,china 4 Key Laboratory of Cenozoic geology and Environment,{3. Academy of sciences,beijing 100029, china MLR Key Laboratory of Saline Lake Resources and Environment Institute of Mineral Resources CAGS Beijing 100037 China Research and Development Center for Saline Lakes and Epithermal Deposits Chinese Academy of Geological Sciences Beijing 100037 China institute of geology Chinese Academy of Geological Sciences Beijing 100037 China Key Laboratory of Cenozoic geology and Environment Chinese Academy of Sciences Beijing 100029 China *Correspondence: Mianping ZHENG *Correspondence: Corresponding author. E-mail: zhengmp2010@***

Two sedimentary sections were measured at Tai Co(Co means lake in Tibetan) in western Tibet,*** two sections are almost all composed of clay carbonate beds except in their lower parts where there are carbonized plants at>10 cm depths and dark-colored carbonate clay and clay at 50-70 cm depths,yielding abundant gastropods,ostracods,and *** carbon and oxygen stable isotope values of carbonate,ostracods,and charophytes and ecological features of microfossil communities indicate the following climatic change in the area from 41.4 to 4.5 ka BP:at 41.4-2..2.ka BP,the climate was relatively wet;at 2..2.2..5 ka BP,it was slightly warm-dry;at 2..5-2..5 ka BP,it was warm-wet;at 2..5-2..0 ka BP,it was slightly cold-wet;at 2..5-17.5 ka BP,it became cold abruptly and slightly wet,implying the climate of the last glacial maximum;at 17.5-16.0 ka BP,it was slightly cold-dry;at 16.0-11.8 ka BP,it was slightly warm-wet;at 11.8-10.4 ka BP,it was relatively cold-dry, roughly equivalent to the climate of the Younger Dryas,and at 10.4 ka BP,the temperatures began to rise again;at 10.4-9.4 ka BP,it was slightly warm-wet;at 9.4-8.5 ka BP,there occurred short warm-wet oscillations;at 8.5-7.9 ka BP,it was slightly dry-cold,representing a strong temperature-lowering and drying event in the postglacial stage;at 7.8-6.3.ka BP,it was slightly warm-wet;at 6.3.4.5 ka BP,the climate tended to be cold-dry.4.5 ka BP recorded the maximum aridity since the late part of the late Pleistocene.

关键词： sedimentary environment index paleoclimatic changes late Pleistocene-Holocene(41.4-4.5 ka BP) Tai Co Tibet

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Grain-size features of a Miocene loess-soil sequence at Qinan: Implications on its origin

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Science china Earth sciences 2006年第7期49卷 731-738页

作者： QIAO Yansong1,3. GUO Zhengtang2.1, HAO Qingzhen1, YIN Qiuzhen1, YUAN Baoyin1 & LIU Tungsheng1 1. institute of geology and Geophysics, {2. Academy of sciences, beijing 10002., china 2. institute of Earth Environment, {2. Academy of sciences, Xi’an 710075, china 3. institute of Geomechanics, {2. Academy of {12. sciences, beijing 100081, china 1. institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 3. institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China 2. institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China

In this study, grain-size of 507 bulk samples from the QA-I Mioceneloess-soil sequence at Qinan were analyzed, and the grain-size features are compared with those oftypical Quaternary loess and soil samples, representative lacustrine and fluvial samples. Theresults indicate that the grain-size distribution pattern of the Miocene loess is essentiallysimilar to that of Quaternary loess, but greatly differs from the lacustrine and fluvial *** layers are regularly coarser than soil layers, indicating cyclical climate changes. Mediangrain-size along the 2.3.1 m sequence varies from 6 to 13.μm and the > 63.μm fraction representsonly 5.3. in maximum, 0.9% in average. Long-term grain-size variations are consistent with the loessaccumulation rate at Qinan and with the eolian mass accumulation rate in the North Pacific. Thesefeatures firmly indicate an eolian origin of the studied sequence, and also reveal a coeval changesbetween the long-term changes of eolian grain-size and continental aridity in the dust sourceregions.

关键词： Qinan, Miocene loess-soil sequence, grain-size, eolian origin.

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A New SHRIMP Age of the Xiamaling Formation in the North china Plate and Its geological Significance

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Acta Geologica Sinica(English Edition) 2007年第6期81卷 1103-1109页

作者： GAO Linzhi~(1,*)ZHANG Chuanheng~2.SHI Xiaoying~2.ZHOU Hongrui~2.WANG Ziqiang~2.SONG Biao~(1,3. 1 institute of geology,{2. Academy of geological sciences,beijing 100037,china 2.8} University of Geosciences(beijing),beijing 100083.china 3.beijing SHRIMP Central,100037 beijing,china institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

Setting up the hypostratotype of late Precambrian is the main aim of the research on the Meso-and Neoproterozoic in North *** chronostratigraphic position is the key in this study. However,many key horizons have not been calibrated with the high-quality isotopic *** the reported new U-Pb age with the Sensitive High-Resolution Ion Microprobe（SHRIMPⅡ）,a zircon U- Pb age was obtained of the ash bed in the Xiamaling Formation in North china Plate,yielding a weighted mean;Pb/;U age of 13.8±12.*** is the first SHRIMP U-Pb age from the Xiamaling Formation in the North china Plate,and represents the depositing time of the middle part of the Xiamaling *** zircon age plays an important role to understanding {2. evolution of the North china Plate during Meso-and Neoproterozoic.

关键词： SHRIMP U-Pb Dating Mesoproterozoic Xiamaling Formation North china Plate

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The age of the plant fossil assemblage in the Liuqu Conglomerate of southern Tibet and its tectonic significance

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Progress in Natural Science:Materials International 2006年第1期16卷 55-64页

作者： FANG Aimin1, YAN Zhen1, LIU Xiaohan2. PAN Yusheng1, LI Jiliang1, YU Liangjun1, HUANG Feixing2.and TAO Junrong3.(1.Laboratory of Lithosphere Tectonic Evolution, institute of {3. and Geophysics, {2. Academy of sciences, beijing 10002., china 2. institute of Tibet Plateau Research, {2. Academy of sciences, beijing 100085, china 3. institute of Botany, {2. A cademy of sciences, beijing 100093. china) Laboratory of Lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China institute of Tibet Plateau Research Chinese Academy of Sciences Beijing 100085 China institute of Botany Chinese A-cademy of Sciences Beijing 100093 China

The Liuqu Conglomerate, situated to the south of Yarlung Tsangbo Suture Zone (YTSZ), is a suit of molasse formed in a foreland basin of the Himalayan orogenic belt after the collision between the two plates of the Indian and Eurasion, It is of great significance in constraining the younger limit time of the collision of the two plates and providing stratigraphic evidence to reveal the post-colli sional tectonic evolution and uplifting history of the Tibet plateau. However, the age of this molasse suit and its correlation to other synchronous strata distributed in southern Tibet have been in great disputes for a long time. Especially in recent years, argues on its ages are growing violently with the recognition of the great sedimentary tectonic significances of this molasse. During the field work carried out recently on this molasse suit, a lot of plant fossils were found preserved in fairly good conditions in the upper part of this strata, which is of great help in determining its age. By identification, the assemblage of the plant fossils belongs to a tropic to subtropic flora developed in the southern margin of the Northern Hemisphere supercontinent during the Middle to Later Eocene, which can provide good constraint on its formation age. This paper is to give a brief introduction of the plant assemblage and its age, and to discuss their tectonic significances.

关键词： Liuqu conglomerate plant fossils age Eocene Tectonic implications.

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SHRIMP zircon U-Pb age and Nd isotopic study on the Nyainqêntanglha Group in Tibet

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Science china Earth sciences 2005年第9期48卷 1377-1386页

作者： HU Daogong1, WU Zhenhan1, JIANG Wan1, SHI Yuruo2. YE Peisheng1 & LIU Qisheng1 1. institute of Geomechanics, chinese Academy of {2. sciences, beijing 100081, china 2. institute of geology, chinese Academy of {2. sciences, beijing SHRIMP Centre, beijing 100037, china 1. institute of Geomechanics Chinese Academy of Geological Sciences 100081 Beijing China 2. institute of geology Chinese Academy of Geological Sciences Beijing SHRIMP Centre 100037 Beijing China

The Nyainqêntanglha Group is traditionally viewed as the oldest metamorphic basement in the Lhasa block, but its formation age and tectonic setting remain debate. Zircons extracted from the metamorphic sequence of volcanics and intrusions of the Nyainqêntanglha Group, 10 km west of Nam Co in northern Lhasa block, have been investigated by cathodolu- minescence (CL), backscattered (BSE) and dated by ion microprobe (SHRIMP). We conclude that the U-Pb age of 787±9 Ma of zircons from the trondhjemite imposes a constraint on maxi- mum protolith age, and minimum formation age of the Nyainqêntanglha Group is constrained by U-Pb age of 748±8 Ma of zircons from the granite. The formation age of the Nyainqêntanglha Group is consistent with sedimentary age of Greater Himalayan rocks, showing that they devel- oped coevally in an arc-basin tectonic setting of Neoproterozoic active continental margin along the northern margin of the India shield. The inherited zircons from the tholetiite and granite give older 2.7Pb/2.6Pb ages from 947 to 1766 Ma. The positive εNd( t ) value indicates that the mafic rocks were derived from the depleted mantle, but contaminated by the older continental crustal material. Integrated Nd model age and U-Pb age data provide excellent evidence for the exis- tence of Mesoproterozoic basement in the Lhasa block during Neoproterozoic time.

关键词： Nyainqêntanglha Group, SHRIMP dating, Nd isotope, Neoproterozoic, Tibet.

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Discovery of Cu-Zn,Cu-Sn intermetallic minerals and its significance for genesis of the Mianning-Dechang REE Metallogenic Belt,Sichuan Province,china

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Science china Earth sciences 2006年第6期49卷 597-603页

作者： XIE Yuling1, HOU Zengqian2. XU Jiuhua1, YUAN Zhongxin2. BAI Ge2.& LI Xiaoyu3.1. Civil and Environmental Engineering School, University of Science and Technology {3., {3. 100083.{2. 2. institute of geology, chinese Academy of geological sciences, beijing 100037,{2. 3. The 109th geological Team, Sichuan Bureau of Mineral Exploration, Chengdu 610100,{2. 1. Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China 2. institute of geology Chinese Academy of Geological Sciences Beijing 100037 China 3. The 109th geological Team Sichuan Bureau of Mineral Exploration Chengdu 610100 China

Mianning-Dechang Himalayan REE Metallogenetic Belt in Sichuan Province lies along the western margin of the Yangtze Craton. We have conducted detailed mineralogical studies on ore minerals collected from Maoniuping and Dalucao, the two largest deposits in the belt. With optical microscope, SEM/EDS, and EPMA, three rare intermetallic minerals, i.e., zinccopperite (Cu2.n), Sn- bearing native copper, and Cu-bearing jupiter were found to occur in the main ore along with barite, fluorite, apatite, sulfide and bastnaesite. Since the conditions under which zinccopperite and Sn- bearing native copper formed are quite unique, finding of these minerals, for the first time in domestic REE deposits, has significant implications for the genesis of the ore deposits in which they occur. In comparison with Cu-Zn intermetallic minerals in other occurrences, we propose that the formation of this REE metallogenetic belt is associated with fast upwelling of the Himalayan magma from deep source.

关键词： Mianning-Dechang REE metallogenetic belt, Cu-bearing intermetallic minerals, EPMA, genesis significance, deep source magmatic activity.

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Lithosphere types in North china:Evidence from geology and geophysics

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Science china Earth sciences 2005年第11期48卷 1809-1827页

作者： QIU Ruizhao1,2. DENG Jinfu3. ZHOU Su3. LI Jinfa4, XIAO Qinghui1,5, WU Zongxu6 & LIU Cui3.1. institute of geology, {2. Academy of geological sciences, beijing 100037, china 2. Development and Research Center, china geological Survey, beijing 100037, china 3. china University of Geosciences, beijing 100083. china 4. china University of Geosciences, Wuhan 43.074, china 5. Information Center of Ministry of Land and Resources, beijing 100812. china 6. institute of geology, State Seismological Bureau, beijing 10002., china 1. institute of geology Chinese Academy of Geological Sciences 100037 Beijing China 2. Development and Research Center China Geological Survey 100037 Beijing China 3. china University of Geosciences 100083 Beijing China 4. china University of Geosciences 430074 Wuhan China 5. Information Center of Ministry of Land and Resources 100812 Beijing China 6. institute of geology State Seismological Bureau 100029 Beijing China

On the basis of the characteristics of geology and geophysics in North china, three types of lithosphere, namely, the cratonic, the orogenic and the rift lithospheres can be classified. In terms of petrological method (based on the information from Precambrian rock assemblages, igneous activities, deep-seated enclaves, etc.) and the relationship between seismic velocity and rock compositions, the crust-mantle petrological and chemical structure models can be set up. Researching results indicate that the geology and geophysics of North china platform bears the similar characteristics in comparison with those of the global typical cratons. The Eerduosi(Ordos) block located in the west of the North china Platform is a remnant of cratonic lithosphere after the North china platform had undergone “activation” in Mesozoic and “reconstruction” in Cenozoic times. The continental crust consists mainly of TTG rock assemblage while the subcontinental lithosphere mantle mainly consists of strongly depleted harzburgite. The craton was finally formed in late Archaean and early Proterozoic, and has been kept in stability up to present; its crustal-mantle petrological structures of lithosphere can be set up as a reference for the study of North china craton and even Sino-Korean craton. In the Mesozoic period, the middle and east areas of North china platform were activated in the Yanshanian orogenic process, the continental crust was reformed by material and heat-transfer of convective mantle and the original crustal TTG component was reconstructed to be granitic crust, and the subcontinental lithosphere man- tle was replaced by the Yanshanian harzburgite-lherzolite. The Yanshan-Taihang Mountains were the remnants of orogenic lithosphere after the rifting in eastern North china in Cenozoic. The present thickness of continental crust and lithosphere in the Yanshan-Taihang Mountains is not equal to their thickness during the Yanshanian orogenic movement because they had undergone the

关键词： lithospheric types,evidence of geology and geophysics,crust-mantle petrological structure,deep process

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Early-Middle Permian Reef Frameworks and Reef-building Models in the Eastern Kunlun Mountains

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Acta Geologica Sinica(English Edition) 2001年第2期75卷 115-125页

作者： TIAN Shugang institute of geology, {2. Academy of {3. sciences, beijing 100037and FAN Jiasong institute of geology and Geophysics, {2. Academy of sciences, beijing 10002. institute of geology Chinese Academy of Geological Sciences Beijing 100037 institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 [?]3.ian Shugang Born in September 1951 graduated from beijing University in 1977 and received his MS. and Ph. D. degrees at china University of Geo{2. (beijing) in 1985 and 1988 respectively working now in the institute of geology Chinese Academy of Geological Sciences. He has long been engaged mainly in studies of biostratigraphy palaeoecology sequence-stratigraphy and reefs. Tel: 010–68328223 E-Mail: sgtian2.01@***

Reef frameworks and building models of the Early-Middle Permian in the eastern Kunlun Mountains have been verified through studies of reef-building communities, palaeoecology and carbonate facies. The eastern Kunlun reefs are built mainly by 6 reef-building communities, which include 11 major categories of frame-building organisms and 6 categories of reef-associated organisms. Eight types of reef-frames have been distinguished and eleven kinds of rocks identified to belong to 6 reef facies. Three sorts of reefs classified by previous researchers, namely mudmounds, knoll reefs and walled reefs, are well developed in the study area. Such reef-facies association and reef distribution show that there are 4 models of reef growth and development, i.e. the tidal-bank knoll-reef model, the plateau-margin wall-reef model, the composite wall-reef model and the deep-water mudmound model. The reefs are mainly constructed by calcareous sponge and calcareous algae, which are similar to all Permian reefs in other area

关键词： reef model Early-Middle Permian eastern Kunlun reefs

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Re-Os(ICP-MS)dating of the massive sulfide ores from the Jinchuan Ni-Cu-PGE deposit

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Science china Earth sciences 2005年第10期48卷 1672-1677页

作者： YANG Gang1,2. DU Andao1, LU Jiren3. QU Wenjun1 & CHEN Jiangfeng2.1. National Research Center of Geoanalysis, beijing 100037,{3. 2. Laboratory for Earth Material Cycling, School of Earth and Space {2., University of Science and Technology of{3., Hefei 2.002.,{3. 3. institute of Mineral Resource, chinese Academy of geological {2., beijing 100037,{3. National Research Center of Geoanalysis beijing china Laboratory for Earth Material Cycling School of Earth and Space Sciences University of Science and Technology of China Hefei China institute of Mineral Resource chinese Academy of {2. {3. beijing china

Massive sulfide ore from the Jinchuan Ni-Cu-PGE deposit was dated by Re-Os technique using Carius Tube digestion, Os distillation, Re extraction by acetone and ICP-MS measurement. An isochron giving an age of 83. ± 3. Ma, initial 187Os/188Os ratio of 0.2.9 ± 0.018 (MSWD = 1.7) and γOs = 13. ± 15 is obtained. The Re-Os age obtained agrees, within analytical uncertainties, with previous SHRIMP zircon U-Pb age of 82. ± 8 Ma (n=5, MSWD = 4.3.. The result suggests that the deposit was formed at Neoproterozoic and that the formation of the Jinchuan Ni-Cu-PGE sulfide deposit may be closely related to the plume activity, which were attributed to the breakup of the Rodinia supercontinent. The high γOs of the massive ores sug-gests that crustal material was involved in the formation of the Jinchuan deposit, however, the quantity of the added crustal material is less than 10%.

关键词： Jinchuan Ni-Cu-PGE deposit, Re-Os dating, ICP-MS.

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^(40)Ar/^(3.)Ar Thermochronological Constraints on the Timing of Collisional Orogeny in the Mian-Lite Collision Belt,Southern Qinling Mountains

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Acta Geologica Sinica(English Edition) 1999年第2期73卷 208-215页

作者： LI Jinyi, WANG Zongqi and ZHAO Min institute of geology, {2. Academy of {3. sciences, beijing 100037 chinese Acad Geol Sci Inst Geol Beijing 100037 Peoples R China

Silurian, Devonian and Carboniferous geological bodies in the Mianxian-Lueyang (Mian-Lue) collisional belt (MLB) and its neighbouring areas, southern Qinling Mountains, china, show similar characteristics of having undergone deformation of two stages. The earlier one, which is inferred to be related to collisional orogeny between the Yangtze and Sino-Korean palaeocontinents based on previous geological data, is responsible for large-scale, north-verging recumbent folds and overthrusts, and associated with low greenschist fades metamorphism. 40Ar/3.Ar dating of three muscovite samples taken from different localities yields plateau ages of {3.6.9±0.9 and {3.9.5±1.4 Ma and an apparent age of 194.5±3.0 Ma. Thus, the late Triassic collision between the Yangtze and Sino-Korean palaeocontinents has been constrained.

关键词： Qinling Mountains Mian-Lue collision belt muscovite 40Ar/3.Ar dating collisional orogeny

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