青藏高原西缘壳幔电性结构与断裂构造: 札达-泉水湖剖面大地电磁探测提供的依据

青藏高原西缘札达至泉水湖剖面大地电磁探测结果表明, 研究区被雅江缝合带、班公-怒江缝合带划分为3个构造区域, 由南至北分别为喜玛拉雅地体、冈底斯地体和羌塘地体.研究区内普遍存在中下地壳高导层, 高导层的顶面埋深起伏较大, 冈底斯内的高导层埋深大, 羌塘和喜玛拉雅地体内的高导层埋深较浅.在班公-怒江缝合带南侧高导层埋深最大, 班公-怒江缝合带南北两侧高导层埋深存在一个约20km的错动.冈底斯地体内的地壳高导层呈北倾形态, 南羌塘的地壳具有双高导层.沿剖面的上地壳存在多组规模不等、产状不同的电性梯度带或畸变带, 反映了沿剖面地区的缝合带与断裂带分布情况.根据电性结构特征, 推断了雅江缝合带、班公-怒江缝合带以及龙木措、噶尔藏布等主要断裂的构造特征与空间分布. 

The Electrical Structure and Fault Feature of Crust and Mantle of Western Tibet Plateau: Based on Results of Magnetotelluric Survey along Profile Zhada-Quanshuihu

The research of magnetotelluric (MT) on the profile along Zhada-Quanshuihu on the west of the Tibetan plateau shows that the area is divided into three structural parts by Yalung Tsangpo suture and Bangong-Nujiang suture. From south to north they are Himalaya terrane, Gandese terrane and Qiangtang terrane. The area is widely distributed with high conductive layers, with fluctuating tops. The high conductive layer of Gandese terrane is deeper while that of Qiangtang terrane and Himalaya terrane is shallower. And the deepest high conductive layer is along the south of Bangong-Nujiang suture. The top surface of high conductive layer in the south Bangong-Nujiang suture is at the depth of about 20 km, which is lower than that in north of Bangong-Nujiang suture. The high conductive layer inside Gandese terrane extends northward and in the southern Qiangtang there exist double high conductive layers. In the upper crust along the profile there are groups of lateral electrical gradient zones or distortion zones of different scale and attitude, indicating the distribution of faults and sutures along the profile. According to the character of electrical structure, the structural characteristic and spatial distribution of Yalung Tsangpo suture, Bangong-Nujiang suture and the major faults of Longmucuo and Ger-Zangbo were inferred.