Crust and upper mantle structure beneath western China from P wave travel time tomography
Crust and upper mantle structure beneath western China from P wave travel time tomography
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DOI：
10.1029/2001jb000402
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发表时间：
2002-10
影响因子：
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通讯作者：
Yi Xu;Futian Liu;Jianhua Liu;Hui Chen
中科院分区：
文献类型：
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作者：
Yi Xu;Futian Liu;Jianhua Liu;Hui Chen
[1]利用中国和吉尔吉斯斯坦地震台网记录的局地/区域和远震事件的P波到达时间，通过地震层析成像获得了中国西部地壳和上地幔的三维速度图像。在较浅的深度，相对于相邻的沉积盆地和前陆洼地的较低速度，大多数山带和构造隆起地区的成像速度较高。在中下地壳深处，吉尔吉斯天山为低速物质所覆盖，在中国天山东西部之间存在明显的南北低速带。与塔里木盆地北部和西部相比，塔里木盆地南部的莫霍线在西部昆仑前深度大于50 km。上地幔横向非均质性在深度71 ~ 571 km处较为明显。吉尔吉斯天山、阿勒泰、祁连和东昆仑的上地幔以低速物质为特征，可能与热地幔上涌有关。中国天山与邻近省份的深部耦合模式可分为岩石圈根部的嵌套、分离沉降和逆冲下推。
[1] Three-dimensional velocity images of the crust and upper mantle beneath western China are obtained through seismic tomography by using P wave arrival times of local/regional and teleseismic events recorded in Chinese and Kyrgyzstan seismic networks. At shallow depths, most mountain belts and tectonically elevated areas are imaged as higher velocities, relative to adjacent sediment-filled basins and foreland depressions with lower velocities. At mid-lower crust depths, the Kyrgyz Tian Shan is underlain by lower velocity material and a distinct low-velocity zone in the south-north direction is observed between the eastern and western parts of the Chinese Tian Shan. The Moho of the southern Tarim basin has a greater depth over 50 km in front of the western Kun Lun, compared to the northern and western Tarim basin. Lateral heterogeneity within the upper mantle is apparent at depths from 71 to 571 km. The uppermost mantle beneath the Kyrgyz Tian Shan, Altay, Qi Lian, and eastern Kun Lun is characterized by low-velocity material that is probably related to the upwelling of hot mantle. The lithospheric thickness varies from 120 to 170 km beneath the Chinese Tian Shan and northern Tibetan Plateau to 200–250 km beneath the Tarim basin. Deep coupling pattern of the Chinese Tian Shan with adjacent provinces can be classified into the embedding, detaching and sinking, and underthrusting of lithospheric roots. In addition, the lithosphere of the northern edge of the Tibetan Plateau seems to be thickened, in contrast to the central part of the northern plateau. North dipping low velocities exist in the upper mantle between the Tibetan Plateau and provinces to its north, which might indicate mantle flow from the Tibetan Plateau toward surrounding areas, but it has been blocked by the thick Tarim lithosphere.