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A REVISION ON SIGNIFICANCE AND USING RANGE OF THE LAW OF SUPERPOSITION

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Scientia Geologica Sinica 2001年第2期 129-132页

作者： Zhang Shouxin institute of geology and Geophysics, chinese academy of sciences, beijing,100029, china

The law of superposition is not universal. Its use in stratigraphy has met challenges and puzzles in the past several hundred years. It is a truth only suitable to any local single section of lithostratigraphy, but it is unsuitable for a large region. The author makes four revisions for its significance and use range. Finally, the principle of diachronism suitable to large regions is proposed.

关键词： A REVISION ON SIGNIFICANCE AND USING RANGE OF THE LAW OF SUPERPOSITION rock

GRANITOIDS IN YUEXI OF EASTERN DABIE MOUNTAIN, china

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Scientia Geologica Sinica 1998年第4期 551-557页

作者： Jin Chengwei and Zheng Xiangsheng (institute of geology chinese academy of sciences, beijing 100029, china)

A lot of acid intrusions occur in Yuexi and are intruded in the North Dabie metamorphic Complex. Theycomprise monzo granite-syen ogranlie, granodion ie -quartz monzo di on ie and alkali granit e. Petrographi caland geochemical study of them indicates they were formed in the post-orogenic regimes. It is worthy tomention that an undeformed body ofgranodiorite-quartz monzodiorite is metaluminous (A/CNK, 0.8-0.9)and exhibits a smaller Eu anomaly (Eu/Sm 0.31). All granitoids in Yuexi district have early Cretaceousages of emplacement and negative εNd(0) (- 17 -26). They are plotted as a horizontal zone on εNd,(0)- εSr(0)diagram, indicating these granitoids may be derived from a older earth crust.

关键词： ppm rock china

Genesis of excess argon in phengite and significance of ^(40)Ar-^(39)Ar age spectra for omphacite:A case study on UHP eclogite of South Dabie Terrain,china

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chinese Science Bulletin 2000年第15期45卷 1345-1351页

作者： WANG Songshan, GE Ningjie, SANG Haiqing & QIU Ji1. institute of geology and Geophysics, chinese academy of sciences, beijing 100029, china 2. Department of Earth and Space Science, University of Science and Technology of china, Hefei 230026, china Correspondence should be addressed to Wang Songshan institute of geology and Geophysics Chinese Academy of Sciences Beijing China Department of Earth and Space Science University of Science and Technology of China Hefei China

The Ar-Ar dating of phengite and omphacite in ultrahigh-pressure (UHP) eclogite of Bixiling and Hengchong in the South Dabie Terrain shows that the content range of excess argon is as high as (0.4-1.3)×10 8 mol· g 1. The genesis of the excess argon is discussed. The Ar-Ar age spectra of omphacite could not support the opinion that the UHP metamorphism occurred in Caledon epoch and pre-Caledon epoch.

关键词： South Dabie Terrain ultrahigh-pressure metamorphics phengite omphacite excess argon.

Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

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chinese Science Bulletin 2003年第B6期48卷 37-41页

作者： GE Shulan~(1,2,3), SHI Xuefa~1 & HAN Yibing~1 1. Key Laboratory of Marine Sedimentology and Environmental geology, First institute of Oceanography, State Oceanic Administration. Qingdao 266061. china 2. institute of geology and Geophysics, chinese academy of sciences, beijing 100029. china 3. Graduate School. chinese academy of sciences, beijing 100039. china Key Laboratory of Marine Sedimentology and Environmental geology First Institute of Oceanography State Oceanic Administration Qingdao China institute of geology and Geophysics Chinese Academy of Sciences Beijing China Graduate School Chinese Academy of Sciences Beijing China

The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172 surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe *** L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East china Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are *** the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

关键词：中国黄海表面沉积物磁化率等值线长江黄河旋涡沉积区循环系统

Structural pattern of eastern Himalayan syntaxis in Namjagbarwa and its formation process

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Science china Earth sciences 2004年第2期47卷 138-150页

作者： ZHANG Jinjiang, Jl Jianqing, ZHONG Dalai, DING Lin & HE Shundong1. Department of geology, Peking University, beijing 100871, china 2. institute of geology and Geophysics, chinese academy of sciences, beijing 100029, china Correspondence should be addressed to Zhang Jinjiang (email: zhjj@***) Department of geology Peking University Beijing China institute of geology and Geophysics Chinese Academy of Sciences Beijing China

The structural pattern of the eastern Himalayan syntaxis in Namjagbarwa consists of two series of structures with different styles. One series compiles the earlier ductile contractional and lateral-slip deformation system, formed by nearly north-south shortening within the syntaxis, left-lateral and right-lateral slipping along its western and eastern boundaries respectively. They were possibly produced by the indentation of the Indian continent into Asian continent after India-Asia collision. The peak deformation-metamorphic ages in these structures are 62-60 Ma, ~23 Ma and ~13 Ma. The other series is composed of ductile-brittle normal faults distributing concentrically and dipping toward the outsides of Namjagbarwa Peak. They were probably the collapse structures caused by rapid uplift in a later time and the beginning ages for the normal faulting are about 7.3-6.3 Ma. Keywords Namjagbarwa - eastern Himalayan syntaxis (EHS) - structural pattern - formation process - structural chronology

关键词： Namjagbarwa, eastern Himalayan syntaxis (EHS), structural pattern, formation process, structural chronology.

The crustal structure under Sanjiang and its dynamic implications:Revealed by seismic reflection/refraction profile between Zhefang and Binchuan,Yunnan

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Science china Earth sciences 2005年第9期48卷 1329-1336页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3, LI Jiliang1, LIU Yifeng1 & LIU Zhenkuan4 1. institute of geology and Geophysics, chinese academy of sciences, beijing 100029, china 2. institute of Geophysics, china Seismological Bureau, beijing 100085, china 3. institute of Deposition Resource, chinese academy of Geosciences, beijing 100037, china 4. School of Exploration and Information, china University of Geosciences, beijing 100083, china institute of geology and Geophysics Chinese Academy of Sciences Beijing China institute of Geophysics China Seismological Bureau Beijing China institute of Deposition Resource Chinese Academy of Geosciences Beijing China School of Exploration and Information China University of Geosciences Beijing China

The fault belts in Sanjiang mainly include Jinshajiang-Honghe fault, Lancangjiang fault and Nujiang fault (called Sanjiang faults) in western Yunnan Province, china. By interpreting the wide-angle seismic reflection/refraction profile between Zhefang and Binchuan, which crosses Tengchong and Baoshan blocks in Dianxi (western Yunnan) tectonic zone, we recon- struct the crustal structure with seismic traveltime tomography for crustal P-wave velocity and the seismic scattering image for crustal seismic reflection structure. In this paper, we firstly present the crustal structure images of P-wave velocity and seismic reflection under the wide-angle seismic profile. These results demonstrate that, the crustal velocity structure and seismic reflec- tion structure along the profile can be divided into 3 segments, and there is an obvious difference of crustal structure among the eastern, the western and the middle segment. Generally, crustal P-wave velocities in the Baoshan segment are 0.1―0.2 km/s slower and seismic reflection am- plitudes from Moho discontinuity are stronger than the other 2 segments. In the studied area, crustal thickness is about 40 km, and shows the thickening tendency from west to east along the profile. Additionally, it can be seen that there is one strong-amplitude seismic reflection event as bright points at the depths of 8―10 km, along the segment of 80―115 km of the profile (south- ward of Tengchong); and seismic reflection wave-field from Moho discontinuity varies obviously along the lateral direction. Finally, we make some discussions on the crustal thickening pattern in the Sanjiang fault belt, structural environment of earthquake development and the contact rela- tionship between the Tengchong block, Banshan block and Luxi trough.

关键词： Sanjiang area wide-angle seismic profile crustal structure.

Climate as the dominant control on C_3 and C_4 plant abundance in the Loess Plateau: Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

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chinese Science Bulletin 2003年第2期48卷 1271-1276页

作者： GU Zhaoyan, LIU Qiang, XU Bing, HAN Jiamao, YANG Shiling, DING Zhongli & LIU Tungsheng institute of geology and Geophysics, chinese academy of sciences, beijing 100029, china Correspondence should be addressed to Gu Zhaoyan (e-mail: zgu@ ***) institute of geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Abundance of C3 and C4 photosynthesis plants can be inferred relatively from stable carbon isotopic composi-tion of organic matter in soils. The samples from five sequences of the last glacial-interglacial loess-soil in the chinese Loess Plateau have been measured for organic carbon isotopic ratios (d 13Corg). The organic carbon isotope data show that relative abundance (or biomass) of C4 plants was increased ca. 40% for each sampling site from the last glacial maximum (LGM) to Holocene optimum, and increased southeastward on the Loess Plateau during both periods of LGM and Holocene. Statistic analyses on the steady maximum d 13Corg values of Holocene soils and modern climatic data from the Loess Plateau and Inner Mongolia indicate that the C4 plant abundance increases with increasing temperature and decreasing precipitation. The C4 plant abundance is related much closer with mean April tem-perature and precipitation than annual. These results lead us to deduce following conclusions. First, temperature is the major factor for control on variations in C4 plant abundance in the Loess Plateau from the last glacial to interglacial. In the absence of favorable temperature condition, both of low moisture and low atmospheric CO2 concentration are insufficient to drive an expansion of the C4 plants in the plateau. Second, d 13Corg in the loess-paleosol sequences, as a proxy of the relative abundance of C4 plants in the Loess Plateau, could not be used as an indicator of changes in the summer monsoon intensity unless the tem-perature had changed without great amplitude. Since all C4 plants are grasses, finally, the increase of the C4 plants supports that forest has not been dominant in the ecosystem on the Loess Plateau during Holocene although precipitation and atmospheric CO2 were largely increased relative to those during LGM.

关键词： C3/C4 plants d 13Corg Loess Plateau LGM Holocene.

Nonlinear analysis on the coupling process of electromagnetic vibrator and earth

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Science china Earth sciences 2005年第8期48卷 1175-1182页

作者： CHEN Zubin1,2, TENG Jiwen2, LIN Jun1, ZHANG Linhang1 & JIANG Zhongjin1 1. institute of Intelligent Instrument & Measurement Control Technology, Jilin University, Changchun 130026, china 2. institute of geology & Geophysics, chinese academy of sciences, beijing 100029, china institute of Intelligent Instrument & Measurement Control Technology Jilin University Changchun China institute of geology & Geophysics Chinese Academy of Sciences Beijing China

The linear model based on the hydraulic pressure vibrator has been no longer adaptable to the electromagnetic vibrator. In order to realize the effective transmission of the limited energy from the vibrator to the ground, it is important to study the coupling model of the electromagnetic vibrator and the earth. In this paper, a nonlinear restore term was introduced to the coupling model because of the existence of a large amount of harmonics in the vibrator baseplate. The nonlinear vibration analysis was applied to the model by the multiscale method. In the course of energy transmission from the vibrator to the ground, ultraharmonic resonance was used to explain the generation of harmonics. An improved scheme was advanced to select the cross correlation reference signal in the vibrator seismic exploration. Good application results were obtained in field experiments.

关键词： vibrator, coupling model, electromagnetic, nonlinear vibration.

Geothermal Characteristics and Geological Implications of Major Tectonic Units in china

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Journal of Earth Science 2000年第3期19卷 152-157页

作者： Wang Yang Faculty of Earth sciences and Mineral Resources, china University of Geosciences, beijing 100083, china Wang Jiyang institute of geology and Geophysics, chinese academy of sciences, beijing 100029, china Deng Jinfu Faculty of Earth Scie

On the basis of more than 900 heat flow data in china and the surrounding seas, the authors study the geothermal characteristics of major tectonic units in china. The spatial pattern of heat flow and other thermal parameters for lithosphere exhibit significant lateral variation, originating from the Cenozoic tectonothermal activities related to the subduction of the Pacific plate and the collision between India and Asia. The mechanical strength of the crust and the seismicity of tectonic units were strongly affected by geothermal characteristics of units. The crustal heat production rate also shows the lateral heterogeneity, implying the significant lateral variation of bulk composition of the crust in china.

关键词： heat flow effective elastic thickness heat production rate of crust china.