摘要
为了研究班公湖-怒江缝合带的壳幔电性结构及构造特征,并为其俯冲极性提供电性约束,对青藏高原中部申扎-双湖大地电磁测深剖面进行全面数据处理分析,获得了可靠的二维电性结构模型,研究表明:沿剖面上地壳分布的是规模不等的高阻体,底面埋深在10～25 km变化,高阻层之下发现由不连续的高导体构成的中下地壳高导层.通过对电性结构的分析,认为班公湖-怒江特提斯洋的俯冲消亡极性可能是双向的,随后拉萨-羌塘地体碰撞带处的上地壳高阻体发生拆沉,以上两次动力学事件可能共同作用于缝合带处的壳幔高导体,同时北拉萨地体的壳幔高导体还可能体现了构造作用、岩浆活动和成矿作用之间的关系.
To understand the crust-mantle electrical structure and the tectonic feature of Bangong-Nujiang suture, and offer the electrical constraints to its subduction polarity, the magnetotellurics data of the Shenzha-Shuanghu magnetotelluric profile in the central Himalaya-Tibetan Plateau was carefully processed and analyzed, obtaining a reliable 2-D electrical model. The study represents that there are some different scale resistors distributed along the profile in the upper crust and the bottom depth varying from 10 to 25 km, and meanwhile there is a middle-lower conductive layer composed of some discontinuous conductivities beneath the resistive layer. With the analysis of the electric structure, the study indicates that the subduction polarity of the Bangong-Nujiang Tethyan ocean may be double-sided, and subsequently the detachment of the upper crustal resistor was occurred, and so the twice dynamics above may contribute to the formation of the conductor within the suture. Furthermore, the conductor beneath the northern Lhasa terrane may also reflect the relation among the dynamics, magmatism and mineralization.