Abstract: A new MT study was conducted along the profile EHS3D-3(Xiachayu of Tibet-Qingshuihe of Qinghai)in 2007.The preferred 2-D model suggests that:1)the upper crust consists of separated resistive blocks;2)in mid-lower crust there is an extensive conductor beneath Lhasa block and Qiangtang terrain respectively due to aqueous fluids and/or partial melts and are inferred to as crustal flow channels at depth of Tiebtan Plateau;3)Yarlun-Zangbo and Bangonghu-Nujiang sutures are indicated by two conductive layers dipping to the north;4)Jinshajiang Fault might be a fracture belt of upper crust that was thinned and destructed by the upwelling of the hot/conductive body at depth.

Key words: magnetotelluric sounding, EHS3D, mid-lower conductor, flow channel, the eastern Tibetan Plateau

摘要： 主要介绍青藏高原东部下察隅—清水河(EHS3D-3)剖面的大地电磁(MT)探测结果。根据2007年沿该测线观测的MT数据,经过资料处理、分析和二维反演,得到了研究区岩石圈的电性结构。结果表明:沿剖面电阻率分布具有纵向成层,横向分区的特征;上地壳由不同大小的高阻体构成;拉萨地块和羌塘地体中下地壳分别存在一个大范围的低阻体,初步认为这2个低阻体由深部流体以及部分熔融所致,可能是高原东部环绕东构造结的2个物质流通道,同时也是高原南北两侧的2个主要剪切走滑带;雅鲁藏布缝合带和班公-怒江缝合带均表现为向北逐渐加深的相对低阻带,可能是俯冲板片表面低阻物质的反映;金沙江断裂深部表现为强烈的低阻体异常,但与该区其它缝合带的电性特征区别较大。

关键词: 大地电磁测深, EHS3D, 电性结构, 通道流, 青藏高原东部