地震层析对印度板块向北俯冲的认识  

Seismic Tomographic Constraint on the Northward Subduction of the Indian Plate

作　　者：薛光琦[1] 宿和平[2] 钱辉[2] 姜枚[2] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质学报》2006年第8期1156-1160,T0005,共6页Acta Geologica Sinica

基　　金：国土资源部"青藏高原的碰撞造山作用及其效应专项"项目(编号2001010206);中国地质调查局"中国重要成矿带找矿模型及技术方法"项目(编号1212010561605);美国NSF(编号EAR99-09609)资助的成果。

摘　　要：通过对中美合作Hi-CLIMB项目在尼泊尔境内及西藏萨嘎以南采集的宽频地震数据的分析研究,笔者用远震层析反演方法对喜马拉雅—西藏碰撞带之下一些关键地段的关键性深部信息进行探讨,进一步证实印度板块在向北俯冲时,引发最剧烈的构造变形发生在其前缘并展示了向北缓倾的主边界断裂(MBT)和3次出现在剖面上的主中央断裂(MCT)的赋存特征;另外,自尼泊尔南缘至雅鲁藏布江断裂处有一条向北缓倾的界面,南端深为10km左右,北端约为25km;由于俯冲、挤压和缩短造成了高喜马拉雅和特提斯喜马拉雅地壳增厚并由此造成了热地壳以及壳内局部熔融存在的现实。Based on a study on the broadband seismic data obtained by Hi-CLIMB project in Nepal and areas south to Saga, Tibet, the deep information over some key sections under the Himalayan-Tibetan Collision Zone is discussed in this paper, using teleseismic tomography. It is further approved that along with the northward subduction of Indian Plate, the strongest tectonic deformation occurs at its front edge, and the hosting state is also illustrated on the slightly north dipping Main Boundary Thrust （MBT） and the Main Central Thrust （MCT） presenting 3 times along the section. On top of that, a north flat-dipping interface is shown from southern border of Nepal through the Yarlung Zangpu Fault, with a depth of -10km at the south end and 25km at north. It is concluded that the crustal thickening over High-Himalayan and Tethys-Himalayan is caused by the subduction, extrusion and shortening, giving birth to a hot crust and partial melting in the crust.

关 键 词：喜马拉雅 逆冲断裂 地震 速度 

分 类 号：P542.4[天文地球—构造地质学]