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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, beijing 10002. Institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 [?]2wu Genyao Male born in 1946 graduated from the Department of geology Peking University in 1968 obtained a DSc degree in 1985 now a research professor with the Institute of geology and geophysics Chinese Academy of Sciences. His main research interest is regional tectonics and he has been working on the tethysides in South China and adjacent areas since 1987. Tel: (010) 62008118 Fax: (010) 62010846 E-mail: dizhikx@***

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

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, chinese 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

General regularity of dynamic responses of slopes under dynamic input

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Science china(Technological sciences) 2003年第z1期46卷 120-132页

作者： QI Shengwen, wu Faquan & SUN Jinzhong Institute of geology and geophysics, chinese academy of sciences, beijing 10002., china College of Engineering Technique, china University of Geosciences, beijing 100083, china chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China china Univ Geosci Coll Engn Techn Beijing 100083 Peoples R China

Through lots of numerical simulations with FLAC3D, dynamic responses of slopes are comprehensively studied in this paper and the general regularities of the isoline of the coefficient of the displacement, velocity and acceleration of the slope section are reached. Given a certain material slope, if the height of the slope is less than a certain value, the displacement, velocity and acceleration linearly enlarge with elevation in the vertical direction; if the height of the slope surpasses the certain value, the displacement,velocity and acceleration do not linearly enlarge with elevation any more, on the other hand, they fluctuate with a certain rhythm. At the same time, the rhythm appears in the horizontal direction, and the displacement, velocity and acceleration of the slope surface enlarge near the slope surface. The distribution form of the isoline of the coefficient of displacement, velocity and acceleration in the section of the slope is remarkably affected by the slope angle. In the certain area near the slope surface, the isoline of displacement,velocity and acceleration is parallel to the surface of the slope; in the mean time the strike direction of the extremum area is parallel to the surface of the slope, too. The charts of the slope dynamic responses can be depicted with two indexes, one is the strike direction of the isoline, and the other is the number of the rhythm extremum area of the direction parallel to the surface of the slope.

关键词： slope, dynamic response, regularity, rhythm.

The upper mantle structure of the Tibetan Plateau and its implication for the continent-continent collision

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Science china Earth sciences 2005年第8期48卷 1158-1164页

作者： wu Qingju1, ZENG Rongsheng1 & ZHAO Wenjin2 1. Institute of geophysics, china Earthquake Administration, beijing 100081, china 2. Institute of geology, china academy of Geological sciences, beijing 100037, china 1. Institute of geophysics China Earthquake Administration 100081 Beijing China 2. Institute of geology China Academy of Geological Sciences 100037 Beijing China

The upper mantle structures of Himalayas-Tibet have been obtained from the mi-gration of receiver functions of the teleseismic events recorded by INDEPTH-III. The result of migration imaging shows a dipping interface subducting northward from the depth of 100 km to the 410-km discontinuity underneath southern Tibet. It indicates that the lithospheric mantle of the Indian continent had been detached from the crust and deeply subducted to the upper mantle of Eurasia during the Indo-Eurasian collision. This kind of continent-continent collision process is fundamentally different from the oceanic collision.

关键词： Tibetan Plateau, receiver function, upper mantle structures, Indo-Eurasian collision, dipping interface.

Rainfall-induced landslide stability analysis in response to transient pore pressure——A case study of natural terrain landslide in Hong Kong

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Science china(Technological sciences) 2003年第z1期46卷 52-68页

作者： LAN Hengxing, ZHOU Chenghu C. F. LeeWANG Sijing & wu Faquan State Key Laboratory of Natural Resources and Environmental System, Institute of Geographical Sci-ences and Natural Resources Research, chinese academy of sciences, beijing 100101, china Department of Civil Engineering, Hong Kong University, Hong Kong, china 3. Institute of geology and geophysics, chinese academy of sciences, beijing 10002., china chinese Acad Sci State Key Lab Nat Resources & Environm Syst Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China Univ Hong Kong Dept Civil Engn Hong Kong Hong Kong Peoples R China chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

Transient pore pressure in response to short intense rainfall process plays an important role in shallow landslide occurrence. Using GIS technology, we carry out the rainfall-induced landslide stability analysis in response to transient pore pressure by means of transient and unsaturated rainfall infiltration modeling. A case study is performed on the shallow landslide stability analysis in Hong Kong. Detailed analysis and discussion reached some useful conclusions on the tempo-spatial behavior and characteristics of slope stability response and pore pressure response to typical rainfall process. Comparison analysis is performed on some important issues including landslide stability response in different types of slopes with different hydraulic properties, antecedent rainfall and landslide stability, and the nature of pore pressure response time. These studies might give us an important insight into landslide tringgering mechanism and the hydrological process in response to rainfall, and provide systematic information and evidences for effective risk assessment and warning system establishment.

关键词： rainfall-induced landslide, transient pore pressure, landslide stability in response to rainfall, GIS.

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 Geological sciences, beijing 100081, china 2. Institute of geology, chinese academy of Geological 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 207Pb/206Pb 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.

Slope Reinforcement for Housing in Three Gorges Reservoir Area

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Journal of Mountain Science 2011年第2期8卷 314-320页

作者： wu Faquan LUO Yuanhua CHANG Zhonghua Institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China Office of Three Gorges Project Construction Committee the State Council of China Beijing 100038 China

The Three Gorges Project of the Yangtze River is the largest hydropower-complex project under construction in the world. Under the largescale relocation projects, 2874 engineered slopes are formed along with the construction of new towns. In this paper, the cutting slopes are mainly soil slopes and rock slopes. Soil slopes include residual soil slopes, colluvial accumulation slopes, swelling soil slopes, and artificial earth fill slopes, etc. Rock slopes include blocky structure rock slopes, layer structure rock slopes, and clastic structure rock slopes, etc. Varied protection measures have been used for slope protection in the reservoir area including shotcrete concrete-anchor bars, frame beams, retaining walls, slope stabilizing piles, sheet-pile walls, anchorage anti-shear tunnels, flexible protection grids, and drainage, etc. Besides, slope deformation monitoring systems have been set up to monitor deformation failure and the stability state of slopes. The protection measures have guaranteed slope safety and maintained a harmony with the urban environment and surrounding landscape.

关键词： Slope reinforcement Housing for resettlement Three Gorges Reservoir

Dating of the Karakorum Strike-slip Fault

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Acta Geologica Sinica(English Edition) 2001年第1期75卷 10-18页

作者： ZHOU Yong, XU Ronghua, YAN Yuehua, PAN Yusheng,Tsanyao Frank YANG, Wei LO and wu Chunming Laboratory of Lithosphere Tectonic Evolution, Institute of geology and geophysics, chinese academy of sciences, beijing 10002.Department of geology, National Taiwan University, 245 Choushan Road, Taipei 106-17, TaiwanDepartment of geology, chinese Culture University, Hwa-kang, Yang-Ming-Shan, Taipei, Taiwan Institute of geology, chinese academy of Geological sciences, beijing 100037 Laboratory of Lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 Department of geology National Taiwan University 245 Choushan Road Taipei 106–17 Taiwan Department of geology Chinese Culture University Hwa-kang Yang-Ming-Shan Taipei Taiwan Institute of geology Chinese Academy of Geological Sciences Beijing 100037 [?]5Zhou Yong Male born in 1968 graduated from Chengdu College of geology with a master's degree in 1991. From 1991 to 1995 he focused on ore deposit investigation. Since 1995 he has studied structural geology associated with the Qinghai-Tibet plateau. Tel: (010) 62008438.

This paper mainly discusses the timing of the Karakorum strike-slip fault, and gives a brief introduction of its structures, offset, and deformational style. This fault strikes NNW-SSE. Asymmetrical folds, stretching lineation, S-C fabrics, feldspar and quartz s?-porphyroclasts, domino structure, shear cleavages and faults in the fault zone are products of tectonic movements. They all indicate a dextral slip sense of faulting. Mylonitic bands are widely developed along this fault. Phengite appears, indicating rather high deformational pressure. Geochronological data indicate that the Karakorum strike-slip faulting occurred from 6.88±0.36 to 8.75±0.25 Ma. The cumulative displacement from Muztag Ata to Muji is about 135 km.

关键词： Karakorum fault kinematics timing displacement

The Yadong-Golmud Geoscience Transect in the Qinghai-Tibet Plateau

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Acta Geologica Sinica(English Edition) 1990年第2期64卷 115-127页

作者： wu Gongjian Xiao Xuchang Li Tingdong chinese academy of Geological sciences, beijing Jia Zhongpeng chinese academy of Geological sciences Beijing 1This project was financially supported by the National Natural Science Foundation of china and the Min-istry of geology and Mineral Resources.

On the basis of abundant geological and geophysical data. 6 terranes have been distinguished on theQinghai-Tibet Plateau. The plateau is a single integrated lithospheric unit although it is divided into blocks.With Amdo as a boundary. the crust may be divided into two parts with different crustal structures. The struc-ture in the southern part is complex, while that in the northern part is simple. The current study has revealedthat 8 factors such as slab subduction. overthrust and superimposition are responsible for crustal shorteningand thickening in the region. The uplift of this region is possibly due to northward compression of the Indianplate and southward compression of the Eurasian plate with the former predominating. The compression led tothe asthenospheric movements which were also influenced by thermal activity caused by doming at the bound-ary between the core and mantle.

关键词： The Yadong-Golmud Geoscience Transect in the Qinghai-Tibet Plateau