喜马拉雅西构造结区深部地球物理场特征剖析

本文基于喜马拉雅西构造结地带区的重力场、电磁波场和地震波场特征，从不同学科的角度对喜马拉雅西构造结区深部地球物理场做了分析.不同学科的研究成果表明，西构造结区不仅存在着令人瞩目的中、深源地震，而且其重力场、电磁波场和壳、幔地震速度结构存在着高度的非均匀性.这不仅表明其在不同演化阶段和不同物质组成先后参与了岛弧与大陆、大陆与大陆碰撞的造山过程及其导致的横向结构特征的显著差异上，同时也反映出这种复杂过程在对深层演化进程所带来的影响，故导致了西构造结区的形成和长期演化的复杂过程.显然西构造区的介质属性、构造格局和深层过程均制约着、并强烈影响着高原西北缘及其西部的深、浅构造组构和运动学与动力学响应.故在青藏高原的动力学模型构建中占有着重要地位.由于西构造结区深部结构和动力学研究工作尚少，而又因自然条件和政治环境的制约，故该区深部物质与能量的交换和其物理-力学过程等核心问题尚有待于加强研究和探索.

Features of the deep geophysical field beneath the Western Himalayan Syntaxis

Based on characteristics of the gravity field, electromagnetic field and seismic wave field in the Western Himalayan Syntaxis area, deep geophysical fields of this region are analyzed from various subject views. Studies of different subjects show that not only intermediate and deep focus earthquakes oceur in this region, high heterogeneity also exists in its gravity field, electromagnetic wave field and crust-mantle velocity structure. This demonstrates that the apparent horizontal structure variations are the results of multiple orogenic events through the collision between the island-arc and continent, or between the continents, as well as the striking evolution process in deep layers affected by the complicated orogenic movements. Such variations in properties further indicate the complexity of the formation processes and evolution in Western Himalayan Syntaxis zone over long geological periods. Obviously, the medium properties, tectonic framework and deep process of the Western Himalayan Syntaxis strongly restrict and influence the tectonic structure and kinematic-dynamics responses in the north western margin and the western region of the Tibetan Plateau, and so that play an important role in the Tibetan dynamic model. Since there are few studies on deep structure and dynamics progress of the Western Himalayan Syntaxis region, and also restricts from natural and political conditions, further studies and exploitations are needed on such key problems as the exchange of matter-energy at depth and its physical-mechanical process.