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geological EVOLUTION AND OROGENY OF EAST KUNLUN TERRAIN ON THE NORTHERN QINGHAI—TIBET PLATEAU

地学前缘 2000年第S1期7卷 234-235页

作者： Xu Zhiqin, Yang Jingsui, Li Haibing(institute of geology,{2., beijing 100037,China)

The East Kunlun terrain is located on the northern Qinghai—Tibet plateau, composed of the East Kunlun Mountain and the Qaidam Basin and bounded by the Qilian terrain on the north and Bayanhar—Songpan Ganze terrain on the south. It is regarded as a composite orogenic belt characterized by having developed superimposed ductile tectonic regimes reflecting the collision orogeny during Early Paleozoic and Triassic periods. It has also experienced transformation from ductile to brittle deformation caused by the post orogeny, since Jurassic after the formation of the East Kunlun Mountain and the Qaidam Basin. A Paleozoic subduction complex zone was recently recognized along the north border of the East Kunlun terrain from Da Qaidam to Dulan (Xu,et al, 1 999). It is composed of ophiolite (of Early Paleozoic age?), tectonic melange and very high\|pressure metamorphic rocks with eclogite (\%p\%=2.2.Pa, \%t\%=72.℃) (Yang,et al.,1998) and garnet\|peridotite (\%p\%=2.5GPa, t =837℃). The Anyemaqin Triassic subduction complex zone trending in NWW\|SEE was developed along the eastern segment of the south border of the East Kunlun terrain. It is mainly composed of ultramafic and mafic rocks, pillow basalt, radiolaria\|bearing clastic rocks, tectonic melange and mylonite. The subduction complex zone contains a series of the southward overthrusting imbricated slices. Instead of this subduction complex zone, a 2.km\|wide sinistral strike\|slip ductile shear zone trending in E\|W was developed along the western segment. On the basis of macroscopic and microscopic studies on a series of structural sections, we divide the East Kunlun Mountain into four tectonic units as follows: (1) North Proterozoic Metamorphic Basement Zone; (2. South Early Paleozoic—Triassic Superimposed Fold Zone; (3) South Triassic Transpression Zone; (4) Anyemaqin Back\|Arc Decollement\|Thrust Zone.

关键词： East Kunlun terrain composite orogenic belt subduction compl ex zone transpression shear zone

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SHRIMP U-Pb dating and Hf isotopic analyses of Middle Ordovician meta-cumulate gabbro in central Qiangtang, northern Tibetan Plateau

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Science China Earth sciences 2010年第5期53卷 657-664页

作者： ZHAI QingGuo1 WANG Jun1, LI Cai2.& SU Li3 1 institute of geology,{2., beijing 100037, China 2.College of Earth sciences, Jilin University, Changchun 130061, China 3 The geological Laboratory Center and State Key Laboratory of geological Processes and Mineral Resources, China University of Geo- sciences, beijing 100083, China institute of geology Chinese Academy of Geological Sciences Beijing China College of Earth sciences Jilin University Changchun China The geological Laboratory Center and State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences Beijing China

Metabasites consisting of metamorphic ultra-mafic rocks, cumulate gabbro, gabbro (diabase), basalt, and plagiogranite are exposed at the Taoxinghu area in central Qiangtang, northern Tibetan Plateau. Zircon SHRIMP U-Pb dating for the cumulate gabbro yields a weighted mean age of 467±4 Ma, which is the oldest and most reliable magmatic age in this area. Zircon 176Hf/177Hf ratios range from 0.2.2.15 to 0.2.2.57, with εHf(t) values of 5.02.0.2., indicating that the cumulate gabbro was mainly derived from the depleted mantle. In addition, geochemical data of metabasites suggest that they have similar characteristics to those in the mid-ocean ridge basalts (MORB). The Taoxinghu metabasites may represent the fragment of Early Paleozoic ophiolite in the "Central Uplift" of the Qiangtang, northern Tibetan Plateau.

关键词： Qiangtang cumulate gabbro SHRIMP dating Hf isotope

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Late Precambrian Scissors--Type Opening--Closing Tectonics and Its Dynamics in South China

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Acta Geologica Sinica(English Edition) 1996年第2期70卷 109-122页

作者： Xu Zhigang institute of Mineral Deposits, chinese academy of geological sciences, {2. institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing

In this paper the author first reviews 6 major advances in the study of Precambrian geologyand tectonics of South China during the last decade, and then proposes the following new modelof Late Precambrian scissors-type opening-closing tectonic evolution in the region. (1) Besidesthe Middle-Late Proterozoic low-grade metamorphic basement, there existed a LateArchaean-Early Proterozoic medium- to high-garde metamorphic basement in South China;both of them formed the united Yangtze-Cathaysia (craton) at the end of the Early Proterozoic,with the Jiangxi-Anhui-Zhejiang palaeogulf extending into the inland and the Jiangxi-Anhui-Jiangsu Peninsula lying on the northern side of the palaeogulf.(2. From the Middle Proterozoic,the present Guangxi-Guizhou-Hunan area in the western-central oldland was subjected toextensional rifting and became a rift trough, thus resulting in counterclockwise rotation of the'Cathaysian block' and clockwise rotation of the 'Yangtze block'; moreover, the southwardcompression of the Dabie-Jiaonan block which split from the southern margin of the NorthChina plate and was accreted to the northern margin of the Jiangxi-Anhui-Jiangsu Peninsula ledto the scissors-type closing of the Jiangxi-Anhui-Zhejiang palaeogulf during the Middle-earlyLate Proterozoic, which further influenced the Early Palaeozoic tectonic evolution of the region.

关键词： Yangtze-Cathaysia Jiangxi-Anhui-Zhejiang palaeogulf Late Precambrian scissors-type opening-closing tectonics

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PALEOMAGNETIC ESTIMATE OF THE MESOZOIC—CENOZOIC LATITUDINAL DISPLACEMENT OF TERRENES IN THE QINGHAI—TIBET PLATEAU AND ITS SIGNIFICANCE

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地学前缘 2000年第S1期7卷 325-326页

作者： Li Pengwu, Cui Junwen, Li Li(institute of geology,{2., beijing 100037, China)

The Mesozoic—Cenozoic latitudinal displacement amounts of terranes (or blocks) in the Qinghai—Tibet plateau were calculated in paleomagnetism. These terranes (or blocks) include Tarim and Qaidam blocks, East Kunlun, Baryan Har, Qiangtang, Lhasa and Himalaya terranes. The calculated results are listed in table 1. These results show that:(1) There was the latitudinal displacement difference between central area and southwestern area in the Tarim southern margin since the lower Cretaceous. There was a southward latitudinal movement from the beginning of middle Jurassic or upper Jurassic (Zhou Qingjie, 1992.. The northward movement amounts of the Tarim northern margin since the Paleocene are greater than that of the Tarim southern margin. Tarim southern margin has moved northward about 1100km since the Paleocene, Tarim northern margin has done about 1700km. Qaidam has moved northward about 3100km since lower\|middle Jurassic. The northward displacement amount of Qaidam since Paleocene is about 810km, near to that of the central area, Tarim southern margin.

关键词： Qinghai\|Tibetan plateau paleomagnetism latitudinal displacement

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Quantitative Evaluation of the Sea-level Drop at the End-Permian: Based on Reefs

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Acta Geologica Sinica(English Edition) 2003年第1期77卷 95-102页

作者： WU Yasheng and FAN Jiasong institute of geology and Geophysics, {2. academy of sciences, beijing 10002. chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

The amplitude of pre-Quaternary sea level drop, H, can be calculated by usingthe formula H = D + To, where To is the original thickness from the top of the tidal deposits onthe reef core to the bottom of the tidal deposits on the reef front, or to the bottom of the ancientmeteoric vadose zone, or to the edge of the mixed-water dolostone zone. The identity and similaritybetween the sea-level drop amplitudes calculated from different reefs far away from each otherindicates that such sea-level changes are eustatic rather than relative changes. Evidence of anend-Permian sea-level drop has been found on the Changxingian (i.e. the end of the Palaeofusulinazone) reefs at Ziyun in South China, including algal laminated deposits, sabkha-related dolostone,desiccation cracks, dissolution collapse breccia. According to calculation based on the meteoricdissolution zone of the reef-core sequence at Ziyun, Guizhou province, the amplitude of thesea-level drop at the end-Permian is about 89.3 m. Calculation via the dolomitized upper part of theChangxingian reef in Lichuan, Hubei Province, yields an 88.9 m amplitude of the sea-level drop atthe end-Permian. Comparison shows that the sea-level drop recorded in the two distantly locatedreefs may be of eustatic type. So the amplitude of the sea level drop of the Tethys Sea at theend-Permian might be at least 89.3 m.

关键词： sea-level drop eustatic reef Permian Changxingian

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Algebraically explicit analytical solu-tions for the unsteady non-Newtonian swirling flow in an annular pipe

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Science China(Physics,Mechanics & Astronomy) 2006年第4期49卷 396-400页

作者： CAI Ruixian1 & GOU Chenhua1,2.1. institute of Engineering Thermophysics, chinese {2. of sciences, beijing 100080, China 2. Graduate School, chinese {2. of sciences, beijing 100080, China institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

This paper presents two algebraically explicit analytical solutions for the incompressible unsteady rotational flow of Oldroyd-B type in an annular pipe. The first solution is derived with the common method of separation of variables. The second one is deduced with the method of separation of variables with addition developed in recent years. The first analytical solution is of clear physical meaning and both of them are fairly simple and valuable for the newly developing computational fluid dynamics. They can be used as the benchmark solutions to verify the applicability of the existing numerical computational methods and to inspire new differencing schemes, grid generation ways, etc. Moreover, a steady solution for the generalized second grade rheologic fluid flow is also presented. The correctness of these solutions can be easily proven by substituting them into the original governing equation.

关键词： analytical solution, Oldroyd-B type fluid, swirling flow, non-Newtonian.

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The Early Evolution of the Acanthomorphic Acritarchs in China and Their Biostratigraphical Implication

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Acta Geologica Sinica(English Edition) 1996年第2期70卷 193-206,219-220页

作者： Yin Chongyu and Gao Linzhi institute of geology,{2., beijing institute of geology Chinese Academy of Geological Sciences Beijing

On the basis of a study of the acanthomorphic acritarchs discovered in the Late Proterozoicto Early Cambrian Meishucunian Stage in different regions of China, especially in southernShaanxi and the Yangtze Platform, coupled with a study of the assemblages, morphological cor-relation, microstructure, and evolutional relations of the acanthorphic acritarchs, as well as awide correlation with those found in different regions of the world, the authors discuss the earlyevolutionary stages of the acanthomorphs, features of their assemblages in various stages, theirbiostratigraphical significance, and their evolutionary trend in China.

关键词： acanthomorphic acritarch Late Proterozoic evolutionary stage biostratigraphy

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Mesozoic thrusts and extensional structures in the Daqingshan orogen, Inner Mongolia, and their temporal and spatial relationship

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Progress in Natural Science:Materials International 2007年第2期17卷 177-186页

作者： QI Guowei, ZHANG Jinjiang , WANG Xinshe and GUO Lei ( Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, China School of Earth and Space sciences, Peking University, beijing 100871, China {2. of geology, chinese academy of geological sciences, beijing 100037, China) Key Laboratory of Orogenic Belts and Crustal Evolution MOE School of Earth and Space Sciences Peking University Beijing 100871 China institute of geology Chinese Academy of Geological Sciences Beijing 100037 China

Three large-scale thrusts developed in the Daqingshan orogen, Inner Mongolia, with a northeast-east trending from Louhuashan to Suletu are described in this paper. These northwest-directed thrusts, together with the four tectonic belts (or tectonic sheets) separated by these faults, formed a typical thrusting system. The originally defined Hohhot metamorphic core complex may be a tectonic sheet, making the uppermost tectonic unit of the thrusting system and truncated by the Daqingshan detachment fault on top. The existing tectono-chronological studies showed that the thrusting of this region possibly happened at the same time as the extension along the top detachment fault. This presents that the contraction and extension in Daqingshan orogen were probably simultaneous. The structural pattern of the Daqingshan orogen can be correlated to the Himalayan orogen, and models for simultaneous thrusting and detachment in Himalaya may give a hint for explaining the development of the Daqingshan orogen.

关键词： Daqingshan thrust metamorphic core complex detachment fault contraction-extension transform Himalaya.

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Discovery of eclogite and its geological significance in Qiangtang area, central Tibet

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Science Bulletin 2006年第9期51卷 1095-1100页

作者： LI Cai1, ZHAI Qingguo2. DONG Yongsheng1 & HUANG Xiaopeng11. College of Earth sciences, Jilin University, Changchun 130061, China 2. institute of geology,{2., Bei- jing 100037, China College of Earth sciences Jilin University Changchun China institute of geology Chinese Academy of Geological Sciences Beijing China

Eclogite is first discovered from Qiang- tang area, central Tibet, which occurs as a lens in the high-pressure metamorphic belt comprising glauco- phane-muscovite schist and garnet-muscovite schist, along the south margin of Lungmu Co-Shuanghu Paleo-Tethys suture. A glaucophane 40Ar/39Ar age of 2.0 Ma and a phengite 40Ar/39Ar age of 2.1.9 Ma have been obtained from blueschists associated with eclogite. The rock consists of garnet, omphacite, amphibole, phengite, and rutile, etc, and the jadeite content in omphacite ranges from 32.7% to 38.95%. It is estimated that the temperature of the eclogite is 2.35 GPa. The discovery of Qiangtang ecologite fur- ther supports that there is a suture zone of Indo- chinese epoch in central Qiangtang area, and is very important for discssing the evolution of the pa- leo-ocean and paleo-plate tectonics in this area.

关键词： Qianghai-Tibet Plateau Qiangtang eclogite tectonics.

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New Research Results on Mechanism,Surface Rupture,Deep Controlling Factors and Stress Measurements of the Wenchuan Earthquake—Earth Scientists' Post-quake Actions

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Acta Geologica Sinica(English Edition) 2009年第4期 3-8页

作者： DONG Shuwen chinese academy of geological sciences,beijing {2.,China

It has been a year since the devastating Wenchuan earthquake struck Sichuan Province, China on May 12.2.08,which caused tremendous casualties,geological disasters and economic *** a deep feeling of grief at the sight of the shattered world in quake-stricken areas,geologists and geophysicists once again profoundly felt their heavy responsibilities for geo-hazard prevention and reduction,and resolved to make their due contributions-what we,as scientists,could do for the quake relief efforts and post-quake reconstruction and what scientific explanations we could offer to the public for the occurrence of the devastating natural disaster.

关键词： Earth Scientists New Research Results on Mechanism,Surface Rupture,Deep Controlling Factors and Stress Measurements of the Wenchuan Earthquake Post-quake Actions

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