藏北低速体存在的地震学证据——INDEPTH4宽频地震结果

位于青藏高原东北部的INDEPTH-IV地震探测剖面,始于柴达木盆地南缘,穿越东昆仑造山带、金沙江缝合线,终止于羌塘地体.本文作者利用天然地震体波完成了该区的三维走时残差反演,勾划出了青藏高原东北部的深部构造格局.研究区最显著的现象则是分布在昆仑地体、可可西里地体、羌塘地体北部下地壳、上地幔中的低速体.对其成因,有可能...

Seismological Evidence for the Existence of the Low-velocity Body in Northern Tibet: A Result from INDEPTH-IV Based Broad-Band Seismological Study

The INDEPTH-IV seismic profile, located in northeastern Qinghai-Tibetan Plateau, starts at the north end of Qaidam Basin, extends across East Kunlun Fault Zone, Jinsha Suture, and ends at Qiangtang Terrain. The authors implemented a 3-D travel-time residual reversion using body-wave from the natural earthquake, and outlined the pattern of the deep-seated structure underneath the northeast part of the Qinghai-Tibetan Plateau. The most notable phenomenon in the area of interest is the existence of low-velocity bodies distributed between the lower-crust and the upper-mantle beneath the Kunlun Terrain, Hoh Xil Terrain and the north part of Qiangtang Terrain, probably related to the hot mantle material derived from the collision between the northward thrusting Indian Plate and southward moving Eurasian Plate. The result obviously indicates that the South Kunlun Fault, Central Kunlun Fault and Jinshajiang Fault are all southward thrusting. It is then presumed that the upper -mantle beneath the Qaidam Basin is rigid, where there is no exchange of hot material.