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^(40)Ar/^(3.)Ar dating of shear deformation of the Xianshuihe fault zone in west Sichuan and its tectonic significance

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Science china Earth Sciences 2004年第9期47卷 794-803页

作者： ZHANG Yueqiao1, CHEN Wen2, 3.& YANG Nong1 1. institute of Geomechanics, chinese academy of Geological Sciences, {3. 100081, china 2. institute of geology, chinese academy of Geological Sciences, {3. 10003., china 3. institute of geology and geophysics, chinese academy of Sciences, {3. 100029, china institute of Geomechanics Chinese Academy of Geological Sciences Beijing China institute of geology Chinese Academy of Geological Sciences Beijing China institute of geology and geophysics Chinese Academy of Sciences Beijing China

Based on field geological survey, structural measurements and classical Ar/Ar dating of mica, biotite and K-feldspar, we obtain cooling ages for Miocene left-lateral shear along the Xianshuihe fault zone. The results document two thermal events during the sinistral shear. The early event (12-10 Ma) corresponds to rapid cooling of the Zheduoshan granitic massif from above 700℃ to below 3.0℃. The late event (5-3.5 Ma) corresponds to cooling of granites intruded along the eastern side of the fault zone. These dating results provide important thermochronological constraint on the timing of late Cenozoic eastward extrusion of the Chuan-Dian Block in the SE Tibetan margin.

关键词： Xianshuihe fault zone, Zheduoshan granitic massif, sinistral shear deformation, 40Ar/3.Ar dating, late Cenozoic.

PGE patterns of ores of Dajing Cu-polymetallic deposit in Linxi County, Inner Mongolia:Indicator to source of metallogenic elements

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chinese Science Bulletin 2002年第13期47卷 1119-1124页

作者： CHU Xuelei, SUN Min & ZHOU Meifuinstitute of geology and geophysics, chinese academy of Sciences, {3. 100029, china Key Laboratory of Mineral Resources, institute of geology and geophysics, chinese academy of Sciences, beijing 100101, china Department institute of geology and geophysics Chinese Academy of Sciences Beijing China Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Department of Earth Sciences The University of Hong Kong Hong Kong China

By comparing PGE patterns of sulfide ores with that of basic-ultrabasic dikes occurring in the Dajing Cu-polymetallic deposit, we discover that there are similar positive slopes between the basic-ultrabasic dikes and the black ores composed mainly of sphalerite and galena, reflecting affinity of their source. The PGE patterns of the yellow ores composed basically of chalcopyrite, arsenopyrite and pyrite are actually different. One is close to the pattern of the mantle 1herzolite, and others resemble the pattern of the basic rocks. However, the concentrations of Ru are higher in the yellow ores, reflecting that sulfur attains or approaches saturation in their parent magma. The PGE characteristics of ores and dikes show that the magmas derived from the deep of crust and the metallogenic elements were supplied mainly by growth material of the crust. In addition, the mantle-derived magma also offered some elements.

关键词： Da Hinggan area polymetallic deposit PGE pattern hypomagma.

Searching for the remains of subducted continental slabs

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chinese Science Bulletin 2000年第5期45卷 385-386页

作者： LIU Guangdinginstitute of geology and geophysics, chinese academy of Sciences,{3., china institute of geology and geophysics Chinese Academy of Sciences Beijing China

On the basis of oceanic geological and geophysical observations the global plate tectonics theory wasput forward in the late 1960s. It inherited the essence of mobilism of continental drift and sea-floorspreading, caused a revolution of earth sciences in the twentieth century. But plate tectonics cannotsatisfactorily explain the complicated geological phenomena of continents, it fails in elucidating

关键词： Searching for the remains of subducted continental slabs der Nature

The features of gravity field and deep structure in western part of the South Yellow Sea

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chinese Science Bulletin 2000年第8期45卷 759-764页

作者： WANG Qianshen1 & AN Yulin1. institute of geophysics, chinese {3. of Sciences, beijing 100101, china 2. chinese University of geology, beijing 100083. china institute of geophysics Chinesc Academy of Sciences Beijing China chinese University of geology Beijing China

The gravity data from the sea region to the west of 124° E of the South Yellow Sea have been processed and the feature of gravity fields analyzed. An experience relationship formula on the filter wavelength and corresponding depth has been put forward. Combined with the geological and seismic data, the deep tectonic framework and structural characters as well as possible favourable prospecting district for hydrocarbon in the South Yellow Sea have been discussed and analyzed.

关键词： western part of the South Yellow Sea gravity field deep structure.

Fossil bacteria in Xuanlong iron ore deposits of Hebei Province

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Science china Earth Sciences 2004年第4期47卷 347-356页

作者： DAI Yongding, SONG Haiming & SHEN Jiying institute of geology and geophysics, chinese academy of Sciences,{3. 100029, china institute of geology and geophysics Chinese Academy of Sciences Beijing China

Discovered in Early Proterozoic Xuanlong iron ore deposits are six genera of fossil iron bacteria, i. e. sphere (coenobium of) rod-shaped (monomer) Naumanniella, ellipsoid elliptical Ochrobium,sphere spherical Siderocapsa and chain spherical Siderococcus, chain rod-shaped Leptothrix and Lieskeella, and six genera of fossil blue bacteria, namely sphere spherical Gloeocapsa, Synechocystis and Globobacter, chain spherical Anabaena and Nostoc, and con-strictive septate tubular Nodularia. The biomineralized monomers and coenobia of the two cate-gories of bacteria, together with hematite plates made up the bacteria pelletal, bacteria silky, bacteria fibrous and clasty bacteria pelletal textural lamina. The bacteria pelletal laminae com-bined with other bacteria laminae to make up oncolite, stromatolite and laminate. The precipita-tion of iron oxide was accelerated due to iron and blue bacteria cohabiting on microbial film or mat. The Xuanlong iron ore deposits are microbial binding ore deposits of ocean source.

关键词： iron and blue bacteria, bacteria textural lamina, microbial ore deposits, Late Early Proterozoic.

Landscape evolution and precipitation changes in the Badain Jaran Desert during the last 3. 000 years

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chinese Science Bulletin 2000年第11期45卷 1042-1047页

作者： YANG Xiaopinginstitute of geology and geophysics, chinese academy of Sciences, {3. 100029, china institute of geology and geophysics Chinese Academy of Sciences Beijing China

On the basis of field expeditions into different parts of the Badain Jaran Desert, new evidence of landscape evolution and precipitation changes during the last 3. 000 years has been found from the geomorphological, sedimentological and geochronological studies of the megadune. Different cemented surfaces of palaeo-dunes have been observed in many localities, which are representatives of relatively moister environment. The chronological data show that four periods of more humid environment occurred in the past 3. 000 years. The stabilization of dunes in a large scale and the existence of many palaeo-lakes and lacustrine terraces confirm the periodic fluctuations of climate. It implies that the intensity of westerlies and Eastasian monsoons varied in the region of Alashan, and the periods of higher precipitation took place even in the times close to the last glacial maximum.

关键词： desert palaeo-dune lake global change Badain Jaran.

SHRIMP zircon U-Pb geochronology of early Mesozoic felsic igneous rocks from the southern Lancangjiang and its tectonic implications

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Science china Earth Sciences 2006年第10期49卷 1032-1042页

作者： PENG Touping1,2, WANG Yuejun1, FAN Weiming1, LIU Dunyi3. SHI Yuruo3.& MIAO Laicheng4 1. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou institute of Geochemistry, chinese academy of Sciences, Guangzhou 510640,{3. 2. Graduate University of chinese academy of Sciences, beijing 10003.,{3. 3. SHRIMP isotope Laboratory, chinese academy of Geological Sciences, beijing 10003.,{3. 4. institute of geology and geophysics, chinese academy of Sciences, beijing 100029,{3. Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Graduate University of chinese academy of Sciences Beijing China SHRIMP isotope Laboratory Chinese Academy of Geological Sciences Beijing China institute of geology and geophysics Chinese Academy of Sciences Beijing China

The SHRIMP zircon U-Pb geochronology of three typical samples, including two monzo nitic granites from the Lincang batholith and a rhyolite from the Manghuai Formation are presented in the southern Lancangjiang, western Yunnan Province. The analyses of zircons for the biotite monzonitic granites from the northern (02DX-13.) and southern (20JH-10) Lincang batholith show the single and tight clusters on the concordia, and yield the weighted mean 206Pb/23.U ages of 229.4 ± 3.0 Ma and 23..4 ± 3.6 Ma, respectively, representing the crystallized ages of these granites. The zircons for the rhyolitic sample (02DX-95) from the Manghuai Formation give a weighted mean 206Pb/23.U age of 23..0 ± 5.0 Ma. These data suggest that the igneous rocks from the Lincang granitic batholith and Manghuai Formation have a similar crystallized age. In combination with other data, it is inferred that both were generated at a narrow age span (~23. Ma) and were originated from the postcollisional tectonic regime. An early Proterozoic 206Pb/23.U apparent age of 1977±44 Ma is additionally obtained from one zircon from the biotite monzonitic granite (southern Lincang batholith), indicative of devel- opment of the early Proterozoic Yangtze basement in the region. These precisely geochronological data provide important constraints on better understanding the Paleozoic tectonic evolution of the Tethys, western Yunnan Province.

关键词： SHRIMP zircon U-Pb dating, Middle Triassic, Lincang granitic batholith, Manghuai Formation rhyolite, southern Lancangjiang.

Indosinian Foreland Fold-and-Thrust Belt Bordering Yunnan and Guangxi, china

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Acta Geologica Sinica(English Edition) 2001年第4期75卷 391-397页

作者： WU Genyao institute of geology and geophysics, chinese academy of Sciences, {3. 100029 chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

Recent discoveries of ophiolites indicate that there must be a Palaeotethyan geosuture zone bordering china and Vietnam, which separates the Vietbac block from the South china subcontinent. The Indosinian foreland fold-and-thrust belt bordering Yunnan and Guangxi provided further evidence for the palaeotethysides. The oceanic crust was subducted southwestwards while the magmatic arc migrated northeastwards, and the continent-arc collision occurred in the Late Triassic with the thrusting being extended towards the north or northeast. The features of thrust-nappe structure are discussed, which proved the continental margin of the Palaeotethyan ocean there to be a complicated one. A face-to-face collision occurred first along the NW-striking segment and then along the ENE-striking segment accompanied by transpression or oblique thrusting occurring along the NW-striking one.

关键词： thrust-nappe structure foreland fold-and-thrust belt palaeotethysides border between Yunnan and Guangxi

Vermiform trace fossils from the Precambrian Ruyang Group, western Henan

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chinese Science Bulletin 1997年第3期42卷 251-254页

作者： HU Jianmin, MENG Qingren and LI Wenhou1 Xi’ an College of geology, Xi’an 710054, china 2. institute of {3., chinese academy of Sciences, beijing 100101, china 3.Department of geology, Northwest University, Xi’an 710069, china Xi’an College of geology Xi’an China institute of geophysics Chinese Academy of Sciences Beijing China Department of geology Northwest University Xi’an China

THE origin and evolution of Precambrian lives has been a long-standing controversial problem. It is now generally accepted by most paleontologists that the origin of metazoa can be traced back to more than 1000 Ma, because the Ediacara and latest pre-Ediacara fauna, such as the Huainan fauna, are featured by their diversification of forms, complicated structures

关键词： Precambrian trace fossil Ruyang Group.