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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, beijing 100081, china 2. Institute of geology, Chinese Academy of Geological Sciences, beijing 10003., china 3. Institute of geology and geophysics, Chinese Academy of Sciences, beijing 1.0029, china Institute of Geomechanics Chinese Academy of Geological Sciences Beijing 100081 China Institute of geology Chinese Academy of Geological Sciences Beijing 100037 China Institute of geology and{1. Chinese Academy of Sciences Beijing 100029 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 (1.-1. 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.

Forcing mechanism of the Pleistocene east Asian monsoon variations in a phase perspective

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Science china Earth Sciences 2005年第10期48卷 1708-1717页

作者： TIAN Jun1.2, WANG Pinxian1. CHENG Xinrong1. WANG Rujian1.& SUN Xiangjun1.3.1. State Key Laboratory of Marine {1., Tongji University, Shanghai 200092, china 2. Institute of {1. and {3., Chinese Academy of Sciences, beijing 1.0029, china 3. Institute of Botany, Chinese Academy of Sciences, beijing 1.0093. china State Key Laboratory of Marine geology Tongji University Shanghai{1. Institute of geology and{1. Chinese Academy of Sciences beijing{3. Institute of Botany Chinese Academy of Sciences beijing{1.

The deep sea records from the ODP Sites 1.43.and 1.44 in the northern and southern South{1. Sea (SCS), including foraminiferal δ 1.O and δ 1.0}, Opal% and pollen percentage, reveal that the variations of the east Asian monsoon have been closely correlated with the variations of the Earth’s orbital parameters (eccentricity, obliquity and precession) and the global ice volume on orbital scale. All the monsoonal proxies show strong 1.0 ka, 41.ka and 23.ka cycles. Although G. ruber δ 1.0} of Site 1.43.is coherent with the ETP (ETP= normalized (eccentricity + obliquity-precession) at eccentricity, obliquity and precession bands, most of the coherent relationship focuses on the precession band, and the other monsoonal proxies are coherent with the ETP only at the precession band, which indicate that precession dominates the Pleistocene tropical climate changes. The phase relationship of the monsoonal proxies with the foraminiferal δ 1.O implies that the global ice volume changes have played a significant role in modulating the east Asian monsoon climate, at least dominating the winter monsoon. This forcing mechanism of the east Asian monsoon is apparently different from that of the Indian ocean mon-soon. The variations of the east Asian monsoon at the precession band, at least that of the winter monsoon, have been controlled not only by the sensible heating but also by the latent heating of the surface water in the South{1. Sea.

关键词： South china Sea, ODP, east Asian monsoon, orbital forcing, global ice volume.

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,{1. Earthquake Administration, beijing 1.0081.{1. 2. Institute of geology,{1. Academy of Geological Sciences, beijing 1.003.,{1. 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 1.0 km to the 41.-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.

A preliminary study on seismic design criteria of offshore platforms in Bohai Sea of china

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Earthquake Engineering and Engineering Vibration 2010年第2期9卷 223-231页

作者： Peng Yanju1,Lu Yuejun1,Yan Jiaquan2,Tang Rongyu1,Wang Junqin3.and Li Jiagang3.1. Institute of Crustal Dynamics,china Earthquake Administration,beijing 100085,china 2. Institute of {3.,china Earthquake Administration,beijing 100081,china 3. {1. Research Center of china National Offshore Oil Corp.,beijing 100027,china Institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

This paper analyzes the seismicity in Bohai Sea,introducing a shape factor K to characterize the seismic risk distribution in sub-regions of the sea. Based on the seismic design ground motions for 46 platforms located in the Bohai Sea,a statistical analysis was performed for different peak ground acceleration (PGA) ratios at two different probability levels. In accordance with the two-stage design method,a scheme of two seismic design levels is proposed,and two seismic design objectives are established respectively for the strength level earthquake and the ductility level earthquake. By analogy with and comparison to the Chinese seismic design code for buildings,it is proposed that the probability level for the strength level earthquake and ductility level earthquake have a return period of 200 and 1.00 - 2500 years,respectively. The validity of these proposed values is discussed. Finally,the PGAs corresponding to these two probability levels are calculated for different sub-regions of the Bohai Sea.

关键词： fixed offshore platform seismic design level seismic design objective return period Bohai Sea

Mesozoic-Cenozoic tectonic transition in Kuqa Depression-Tianshan,Northwest china:Evidence from sandstone detrital and geochemical records

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Science china Earth Sciences 2005年第9期48卷 1387-1402页

作者： LI Zhong1. GUO Hong2, WANG Daoxuan3.& LIN Wei1.1. Institute of {1. and {1., Chinese Academy of Sciences, beijing 1.0029,{3. 2. Tarim Oilfield Branch, CNPC, Korla 841.00,{3. 3. Hefei University of Industry, Tunxilu 1.3. Hefei 23.009,{3. 1. Institute of geology and{1. Chinese Academy of Sciences 100029 Beijing Chin 2. Tarim Oilfield Branch CNPC 841000 Korla China 3. Hefei University of Industry Tunxilu 193 230009 Hefei Chin

Similar to compositional evolution of sandstone modes and detrital heavy minerals from different profiles in the Kuqa Depression, Northwest china, major element analysis of whole sandstones from the same profiles shows four discontinuous depositional interfaces or periods, respectively corresponding to Lower Triassic\Middle Triassic, Upper Jurassic\Lower Cretaceous, Lower Cretaceous\Paleogene and Miocene\Pliocene, and indicates five-phase evolution during Mesozoic-Cenozoic: (1. From the first to fifth phase, a depositional suite changes from maroon and coarse clastic, through grey-dark grey and fine, red and coarse, red-mottled, interlayered by gypsum, to brown and coarse clastic assemblages, accompanying detrital component evolution in unstable-stable-unstable-very unstable-very unstable assem- blages. It is indicated that carbonate and complex detritus gradually dominate in sandstones in post-Late Jurassic, with rapid reduction of compositional maturity. (2) For major element geo- chemical parameters of whole sandstones, CaO and Fe2 O * {1.MgO contents show a change sequence in high-low-high-higher-highest values, with rapid increasing in post-Late Jurassic. ({1. Contra some aggregative indicators for weathering indexes of sandstone detrital component, Al2O{1.(CaO+Na2O) and ln(Q/(L+CE)), show a change sequence in low-high-low-lower-lowest ratios, with rapid decreasing in post-Late Jurassic. It is found that sandstone samples of the first, second and later three phases may be distinguished from the A-CN-K and A-CNK-FM diagrams respectively. Therefore, in the Kuqa Depression-Tianshan, the most important discontinuous depositional interface recording paleotectonic and paleoclimatic transition occurred in Early Triassic\Middle Triassic and Late Jurassic\Early Cretaceous, respectively, and, however, tec- tonic differentiations of basin-range system finally result in distinct depositional systems but similar detrital weathering indexes across the Lower Cretaceous\Paleogene

关键词： Tianshan, Kuqa Depression, basin-range, depositional record, tectonic transition, Mesozoic-Cenozoic.

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 {1. and {1., Chinese Academy of Sciences, beijing 1.0029,{3. 2. Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 71.075,{3. 3. Institute of Geomechanics, Chinese Academy of Geological Sciences, beijing 1.0081.{3. 1. Institute of geology and{1. 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 253.1.m sequence varies from 6 to 1.0}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.

Crustal structure of Gondwana-and Yangtze-typed blocks:An example by wide-angle seismic profile from Menglian to Malong in western Yunnan

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Science china Earth Sciences 2005年第11期48卷 1828-1836页

作者： ZHANG Zhongjie1. BAI Zhiming1. WANG Chunyong2, TENG Jiwen1. Lü Qingtian3. LI Jiliang1. SUN Shanxue1.& WANG Xinzheng1.1. Institute of {1. and {1., Chinese Academy of Sciences, beijing 1.0029,{3. 2. Institute of {1., Chinese Seismological Bureau, beijing 1.0081.{3. 3. Institute of Deposition Resource, Chinese Academy of Geological Sciences, beijing 1.003.,{3. 1. Institute of geology and{1. Chinese Academy of Sciences 100029 Beijing China 2. Institute of geophysics Chinese Seismological Bureau 100081 Beijing China 3. Institute of Deposition Resource Chinese Academy of Geological Sciences 100037 Beijing China

The wide-angle seismic profile between Menglian and Malong crosses the Baoshan block (Gondwana-typed), and Simao and southwestern Yangtze blocks (Yangtze-typed). By in-terpreting the wide-angle seismic data, we obtained the seismic crust/upper mantle structure of P-wave velocities together with the seismic reflections of these three blocks, Changning- Menglian and Mojiang suture zones among the mentioned three blocks. Our interpreting results demonstrate that the P-wave crustal velocity of Simao block is slower than that of Baoshan and southwestern Yangtze block and the crustal thickness gradually thickens from the Baoshan block, Simao to southwestern Yangtze block. Crustal reflection patterns of these three blocks have dis-tinct differences too. For the Gondwana-typed blocks, seismic reflections in the upper crust are well developed while in middle-lower crust they are very weak. The crustal reflections in the Yangtze block are very well developed. The crustal reflection patterns in Simao and southwest-ern Yangtze blocks are distinguishable. The average thickness of the crust in the studied area is about 40 km. And we make some discussions on the crustal thickening model of the three blocks in western Yunnan and tectonic setting of seismic developing and interaction of Gondwana and Yangtze blocks.

关键词： Gondwana blocks,Yangtze blocks,wide-angle profile,crustal structure,tectonic setting

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

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Science china Earth Sciences 2005年第7期48卷 1025-1039页

作者： HUANG Fei1. Kealhofer Lisa2, XIONG Shangfa3.& HUANG Fengbao1.1. Nanjing Institute of {1. and Paleontology,Chinese Academy of Sciences,Nanjing 21.008,china 2. Anthropology and Sociology Department,Santa Clara University,CA 95053.USA 3. Institute of {1. and {3.,Chinese Academy of Sciences,beijing 1.0029,china Nanjing Institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States Institute of geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium Chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 1.000 and 8720 a BP, the Aneurolepidium Chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 8720 to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 4200?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3.00 and 21.0 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 21.0 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

Seismic wave propagating in Kelvin-Voigt homogeneous visco-elastic media

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Science china Earth Sciences 2006年第2期49卷 147-153页

作者： YUAN Chunfang1. PENG Suping1. ZHANG Zhongjie2 & LIU Zhenkuan3.1.{1. University of Mining & Technology, {1. 1.0083.{1. 2. Institute of {3., Chinese Academy of Sciences, {1. 1.01.1.{1. 3. Exploration and Development Research Institute of Daqing Oilfield, Daqing 1.3.1.,{1. 1. china University of Mining & Technology Beijing 100083 China 2. Institute of geophysics Chinese Academy of Sciences Beijing 100101 China 3. Exploration and Development Research Institute of Daqing Oilfield Daqing 163712 China

This paper studies, under a small disturbance, the responses of seismic transient wave in the visco-elastic media and the analytic solution of the corresponding third-order partial differential equation. A plane wave solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differ-ential equation with a pulse source is obtained. By the principle of pulse stacking of particle vibration, the result is extended to the solution of Kelvin-Voigt homogeneous visco-elastic third-order partial differential equation with any source. The velocities of seismic wave propagating and the attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are discussed. The velocities of seismic wave propagating and the coefficient of attenuation of seismic wave in Kelvin-Voigt homogeneous visco-elastic media are derived, expressed as functions of density of the media, elastic modulus and visco-elastic coefficient. These results can be applied in inversing lithology parameters in geophysical prospecting.

关键词： Kelvin-Voigt visco-elastic velocity attenuation seismic wave.

Dehydration melting of solid amphibolite at 2.0 GPa: Effects of time and temperature

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Science china Earth Sciences 2005年第8期48卷 1120-1133页

作者： ZHOU Wenge1. XIE Hongsen1. LIU Yonggang1. ZHENG Xiaogang1. ZHAO Zhidan2 & ZHOU Hui3.1. Laboratory of Material in the Earth’s Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002,{1. 2. Department of {1.,{1. University of Geosciences, {3. 1.0083.{1. 3. Department of {1., Peking University, {3. 1.0871.{1. 1. Laboratory of Material in the Earth’s Interior Institute of Geochemistry Chinese Academy of Sciences 550002 Guiyang China 2. Department of geology China University of Geosciences 100083 Beijing China 3. Department of {1. Peking University 100871 Beijing China

Two sets of dehydration-melting with a natural solid amphibolite, collected from North Himalayan structure zone, Tibet, have been carried out in multi-anvil apparatus at 2.0 GPa and 800―1.00℃, for 1.―200 h. One is keeping the pressure at 2.0 GPa and the annealing time of 1. h, changing the temperature (800―1.00℃). The other is keeping the pressure at 2.0 GPa and temperature at 850℃, varying the annealing time (1.―200 h). The products are inspected with microscope and electron probe. The results indicate that at 2.0 GPa, annealing time of 1. h, garnets, melts and clinopyroxenes occur in amphibolite gradually with increasing temperature and the chemical compositions of melt vary from tonalite to granodiorite, and then to tonalite. However, at 2.0 GPa and 850℃, with the annealing time increasing, the garnets, melts and cli-nopyroxenes also occur in amphibolite gradually and the chemical compositions of melt vary from tonalite to granodiorite. In both cases, melts interconnect with each other when the contents of melt are over the 5 vol.%. the viscosities of the melt produced in amphibolite at temperature higher than 850℃ are on a level with 1.4 Pa·s. The interconnected melt with such a viscosity may segregate from the source rock and form the magma over reasonable geological time. Therefore, it is believed that at the lower part of the overthickened crust, the tonlitic and grano-dioritic magma may be generated through the dehydration melting of amphibolite.

关键词： solid amphibolite, high pressure, high temperature, time, partial melting.