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Research On Seismotectonic Features In Xinjiang

Posted on:2009-04-22Degree:MasterType:Thesis
Country:ChinaCandidate:J B ChenFull Text:PDF
GTID:2120360245465335Subject:Structural geology
Abstract/Summary:PDF Full Text Request
By collecting of predecessors'research results, and on the basis of important research results(research on active faults in Urumqi, for example) in recent ten years and evaluation of seismic safety for more than 300 important engineering sites, new cognition and discovery of typical active faults in Xinjiang are made, such as Altai Mountain active faults, Northern Tianshan Mountain piedmont active faults, Urumqi active faults, Southern Tianshan Mountain Kuqa and Kalpin nappe tectonics belts of reverse faults, Taxkorgan fault belts of Western Kunlun and so on. Geometric characters of active faults are collated by means of highly precision and large-scale ETM satellite image data. Database for seismic faults, folds and Quaternary basins in Xinjiang are set up based on GIS software, and it can be updated. The research work provides new seimotectonic information for seismic disaster prevention, earthquake prediction and earthquake emergency and so on.Active faults of Xinjiang related closely to strong earthquakes mainly develop in the transitional zone between basins and mountains. For example, most active faults in Altai region are mainly reverse dextral strike-slip ones, most faults in Tianshan Mountains and West Kunlun region are mainly reverse faults or reverse strike-slip ones, most faults in Kala Kunlun region are mainly dextral strike-slip ones, and most faults in Altun Mountains region are mainly sinistral strike-slip ones. In the process of space development, the nature of active faults will change correspondingly along with stress field. Characters of active faults will change along with transformation of stress fields during the process of space development. There are 206 active faults in Xinjiang from Quaternary, with 88 Holocene active faults and 85 late Pleistocene active faults. These faults distribute widely in the piedmont of northern and southern Tianshan Mountains, Kunlun Mountains, Altun Mountains, Altai Mountains and east-west Junggar. And most of them are seismogenic structures of M≥6 earthquakes, seismic risk regions and potential seismic sources.Kunlun Mountain region can be divided into Pamir-west Kunlun northern margin, western Kunlun fold seimotectonic area and Altun seimotectonic area from west to east. Most of faults in the region are strike-slip ones, such as Kangxiwa fault and Altun fault, and others are reverse faults and normal faults. Fold-belts of reverse-faults develop in the piedmont of Kunlun Mountains with the characteristics of migration from north to south gradually, whose activities from Holocene are strong. And most faults are new ones. In addition, strong earthquakes occur in the active faults of en-echelon graben basin, such as Taxkorgan fault. Tianshan Mountain Region can be divided into four seimotectonic areas from west to east as fallows: southern Tianshan Mountain area, middle Tianshan Mountain area, northern Tianshan area and eastern segment of eastern Tianshan mountain area. The tectonic deformation of Tianshan Mountains is mainly thrust nappes in margin of piedmont and intermontane basin. Compresso-shear faults close to EW develop in the root of the nappes, such as Maidan fault and Beiluntai fault. Active faults mainly locate in the transitional belt of basin and Mountains body. And there are strike-slip faults with direction of NW, such as Boluokenu-Aqikkuduke fault.Altai mountain region can be divided into two parts from west to east, western and eastern seismotectonic areas along Keketuohai-etai fault. Most of faults in western part are reverse faults with NWW direction, such as Eeqis fault, and most of faults in eastern part are strike-slip faults with NNW direction, such as Keketuohai-two fault. Faults in the eastern part with NNW direction are main seismogenic tectonics in the west of Mongolia and Aertai of Xinjiang, most of which incise faults with NWW direction.Northern margin fault of west and east Junggar basin locates in the south of Altai Mountains. Faults of western Junggar basin are mainly sinistral strike-slip ones and normal ones, such as Daerbute fault and Tuoli fault. Ones of eastern Junggar basin which develop along intermountain basin, mainly include Kupu fault, Beitashan piedmont fault, Zhifang fault and Suhaitu fault and so on.
Keywords/Search Tags:Xinjiang, Seismotectonic, Active fault, Late Quaternary, Kunlun Mountains, Tian shan Mountains, Altai Mountains
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