大地电磁法的应用综述:以川滇地区为例

Application of the magnetotelluric method in the Sichuan-Yunnan region—a review

大地电磁法(包括音频大地电磁、宽频带大地电磁和长周期大地电磁)是探测近地表至上地幔深度的地球物理方法之一,以其对低阻体的敏感性,在深部结构探测、地震孕育环境、地球动力学以及地热和资源勘探等领域发挥着重要作用。川滇地区处于特提斯构造域的东段,诸多(微)板块在此碰撞拼贴,是青藏高原内部物质东流或块体侧向挤出的重要通道。川滇地区受板块边界的断裂带或者说缝合带相互切割及影响,是解析区域构造变形、孕震环境以及物质迁移的重要窗口。在简要介绍大地电磁法理论的基础上,也介绍了近年来兴起的人工源极低频电磁方法,本文综述了大地电磁法在川滇地区的应用,主要包括在地震孕育、火山和地热活动、成矿活动、构造与动力学以及电磁同震效应方面的应用,以较全面的视角为地球科学相关领域的学者提供川滇地区大地电磁学领域开展的工作。

Magnetotelluric sounding(MTs,including audio-magnetotelluric,broadband-magnetotelluric and long-period-magnetotelluric)is a geophysical method to probe the near-surface to the upper mantle.Due to its sensitivity to low resistivity bodies,magnetotelluric plays an important role in deep structure,seismogenic environment,geothermal and resource exploration and geodynamics.The Sichuan-Yunnan region,located in the eastern section of the Tethys tectonic domain where many(micro)plates collide and merge,serves as an important channel for the eastward flow of materials and lateral extrusion of blocks within the Tibetan Plateau.The region is an important window to study the regional tectonic deformation,seismogenic environment and material migration due to the mutual cutting and influence of fault zones or suture zones of the plate boundary.This review first gives a brief introduction to the theory of magnetotelluric,then focuses on its application in the Sichuan-Yunnan region as well as the emerging CSELF(control source extremely low frequency)electromagnetic technique in recent years,and finally discusses the application of magnetotelluric in seismogenic environment,volcanic and geothermal activities,metallogenic activities,tectonic and dynamics,and electromagnetic coseismic effects.This review offers a comprehensive perspective on the application of magnetotelluric in the Sichuan-Yunnan region.