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662.
Distribution and dispersal pattern of clay minerals in surface sediments, eastern Beibu Gulf, South China Sea 总被引:3,自引:2,他引:1
Clay minerology of sediments are useful in determining distribution,sources and dispersal routes of fine-grained sediments.In the present paper,clay minerals of surface sediments throughout the eastern part of Beibu Gulf has been investigated to reveal sources and transport of detrital finegrained sediments.Four distinct clay mineral suites were observed from cluster analysis of clay mineral compositions of the samples.From the distribution pattern of clay minerals,we conclude that kaolinte in the eastern gulf is mainly derived from South China Landmass;Smectite could not be transported mainly by surface current from north-western Hainan Island,and maybe minor portion of it from Red River;Illite is mainly transported by the currents from South China Sea.Chlorite has two sources,namely South China Sea and South China Landmass.The Zhujiang River derived sediments could not be one of the sources for the clay mineral here,because of very different composition and ratios.The distribution pattern of clay minerals in the eastern Beibu Gulf is mainly controlled by fine-grained sediment source and local currents.The Silt/Clay,Smectite/Kaolinte,and Smetite/(Chlorite+Illite) ratios could be used as indicators of fine-grained sediment dispersal in the gulf. 相似文献
663.
The microaerobic iron-oxidizing bacteria in circumneutral environment produce extracellular polymeric substances(EPS)with unique morphologic features,such as stalks or sheaths,which can be regarded as geobiological signatures.The Archean and early Palaeoproterozoic oceans were anoxic with high soluble Fe(II)that were suggested to have been oxidized through the metabolism of Fe(II)-oxidizing bacteria.The precursor of the ultrafine hematite in banded iron formation(BIF),e.g.,ferrihydrite,was suggested to be the mineral record of microbial Fe(II)-oxidation at that time.However,both the biological materials and primary iron minerals were prone to being altered by diagenetic or low-grade metamorphic processes.This makes it difficult to interpret the genesis of Precambrian BIFs.Here,we report experimental simulation on the effects of diagenesis or low-grade metamorphism on neutrophilic microaerobic Fe(II)-oxidizing bacteria and their biomass.Stalks,sheaths,and iron oxide spheroidal aggregates are partially preserved after the 100 MPa/300°C treatments,which indicates the mixed organic matters and iron oxides could survive the diagenetic or low-grade metamorphic processes.Some organic-mineral mixing structures carry information on microbial processes,though they appear similar to pseudomorphs of fossilized bacteria. 相似文献
664.
Jie Li Qingxia Yue Jun Chen State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai China School of Civil Engineering Sh ong Jianzhu University Ji’nan China 《地震学报(英文版)》2010,(1):13-24
The modeling methodologies and calculation of dynamic response of underground structure under Rayleigh waves is investigated in this paper. First the free field responses under Rayleigh waves are analyzed and the numerical results agree well with the theoretical results. Then, the approximate Rayleigh waves are put forward based on the preliminary re-search, and Rayleigh wave field is obtained through fast Fourier transform technique. Taking a utility tunnel as an example, its dynamic responses under Raylei... 相似文献
665.
Ecological response to the climate change on the northern slope of the Tianshan Mountains in Xinjiang 总被引:7,自引:2,他引:5
CHEN Xi LUO Geping XIA Jun ZHOU Kefa LOU Shaoping & YE Minquan . Xinjiang Institute of Ecology Geography Chinese Academy of Sciences Urumqi China . Institute of Geographical Resources Sciences Chinese Academy of Sciences Beijing China . Urumqi Meteorological-satellite Land Station Urumqi China . Seismological Bureau of Xinjiang Uygur Autonomous Region Urümqi China Correspondence should be addressed to Chen Xi 《中国科学D辑(英文版)》2005,48(6):765-777
The relationship between the terrestrial ecosys-tems and the climate change is one of the importantfields in the study on global change,and the rela-tionship between vegetation and climate change is oneof the main research focuses[1―3].On the one hand,the high-amplitude global warming results in the increase of evaporation from the oceans and the waters on land and of precipitation in most parts of the oceans and theterrestrial regions,thus,the modern glaciers are seri-ously melted,the runoff … 相似文献
666.
SUN Zhongshi DENG Jun JIANG Yanguo WANG Jianping WANG Qingfei & WEI Yanguang .Department of Earth Sciences Jilin University Changchun China .Department of Geosciences Mineral Resources China University of Geosciences Beijing China .Weihai Gold Institute Shandong Weihai Gold Bureau Weihai China Correspondence should be addressed to Sun Zhongshi 《中国科学D辑(英文版)》2004,47(11):995-1007
The tectonic activities during late Archaean-earlyProterozoic is the crisis during the process of crustevolution. The tectonic kinematical mode and dynamicprocess of metamorphic complexes formed is the keyproblem in geosciences[1—7], related to many importantgeological events, such as the substitute of dynamicalsystems and the corresponding relationship betweendeep crust-mantle structure and upper regional stressfield. The predecessors have made a great deal ofstudy on this topic and achieved… 相似文献
667.
1. IntroductionThe development of global climate and weathermodels requires accurate monitoring of atmospherictemperature and moisture profiles, as well as the con-tents of trace gases and aerosols. It is quite difficultto monitor continuously these parameters on a globalscale.Until recently. AIRS (Atmospheric InfraredSounder) offers a new opportunity to improve globalmonitoring of temperature, moisture, and ozone distri-butions and changes therein. The high spectral resolu-tion (v/Δv ? 12… 相似文献
668.
ZHANG Shifeng LIU Changming XIA Jun TAN Ge LI Lin LIU Caitang ZHOU Changqing & GUO Lei . Institute of Geographic Sciences Natural Resources Research Chinese Academy of Sciences Beijing China . College of Water Resources Hydropower Engineering Wuhan University Wuhan China 《中国科学D辑(英文版)》2005,48(3):417-428
The driving actions are varied during the rain-fall-runoff process in a catchment. The impacts on therunoff process, caused by human activities or climatechange, can be attributed to two aspects: the charac-teristics of rainfall process and ground pad changes.To clarify their impacts on hydrological cycle is thefoundation of mechanism research of scientific hy-drology. So far, all of the research results, domestic andabroad, indicate that the advances on the understand-ing of hydrologica… 相似文献
669.
Song Ruolong Ma Jun Wang Kexie 《应用地球物理》2005,2(4):216-222
The nonsplitting perfectly matched layer (NPML) absorbing boundary condition (ABC) was first provided by Wang and Tang (2003) for the finite-difference simulation of elastic wave propagation in solids. In this paper, the method is developed to extend the NPML to simulating elastic wave propagation in poroelastic media. Biot's equations are discretized and approximated to a staggered-grid by applying a fourth-order accurate central difference in space and a second-order accurate central difference in time. A cylindrical twolayer seismic model and a borehole model are chosen to validate the effectiveness of the NPML. The results show that the numerical solutions agree well with the solutions of the discrete wavenumber (DW) method. 相似文献
670.
An Early Aged Ophiolite in the Western Kunlun Mts., NW Tibetan Plateau and Its Tectonic Implications
XIAO Xuchang WANG Jun SU Li JI Wenhua SONG Shuguang Institute of Geology Chinese Academy of Geological Sciences Beijing Geological Lab Center China University of Geosciences 《《地质学报》英文版》2005,79(6):778-786
1 Introduction The Kuda ophiolite occurred in the western Kunlun Mountains, which lies about the intersection of longitude 77°10′ E and latitude 36°45′ N (Figs. 1, 2). The upper portion of the ophiolite mainly consists of a thick layer of basaltic pillow lavas, which was well exposed along the high way from Xinjiang Uygur Autonomous Region to the western Tibetan Plateau, and the middle-lower part, the mafic-ultramafic cumulates and upper mantle rocks occur at the top of the mountain n… 相似文献