滇西三江地区深部电性结构特征及其意义  

Deep electrical resistivity structure of Sanjiang Area of west Yunnan and its significance

作　　者：于常青[1] 张刚[2] 王绪本[3,4] 罗威[3,4] 李德伟[3,4] 蔡学林[4] 郭紫明[3] 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]西南科技大学环境与资源学院,四川绵阳621010 [3]成都理工大学地球物理学院,成都610059 [4]成都理工大学地球探测与信息技术教育部重点实验室,成都610059

出　　处：《地球物理学报》2017年第6期2385-2396,共12页Chinese Journal of Geophysics

基　　金：中国地质调查局"青藏高原东部及东南部地球物理探测"(1212011121273;1212011121266);国家高技术研究发展计划"长周期分布式大地电磁观测系统"(2014AA06A612);西南科技大学自然基金(15zx7135)资助

摘　　要：沿盈江一姚安布置了一条长约350 km的长周期大地电磁剖面,共观测宽频大地电磁测深点53个,长周期大地电磁测深点26个;利用多种数据处理方法对观测资料进行了预处理、定性分析和二维反演,得到沿剖面的地壳和上地幔电性结构模型.对主要地块和断裂带的电性结构进行了分析,电性结构模型揭示滇西三江地区广泛存在壳内低阻层,但沿剖面方向即东西向埋深和厚度不一,在保山地块和滇中地块地下存在较大规模的壳幔低阻带;腾冲地块地下埋深13~20 km,厚约10~17 km的壳内低阻层可能是岩浆囊的反映;初步将保山壳幔韧性剪切带作为印支地块挤出的深部东边界.A 350 km long-period Magnetotelluric profile is placed along Yinjiang-Yaoan. Altogether 69 broadband magnetotelluric sounding stations and 19 long-period magnetotelluric sounding stations were laid. After pre-treatment, qualitative analysis, and two-dimensional inversion of the observed field data by several data-processing methods, the crust and upper mantle electrical resistivity model along the profile is obtained. An analysis is made on the electrical resistivity structure of the main land blocks and faults, and the resistivity model reveals that there widely exist low resistivity zones in the crust in Sanjiang area at the Southeast edge of Qinghai-Tibet Plateau, the low resistivity zones differ in burial depth and thickness from east to west, and there exist massive crust-mantle low resistivity zones in Baoshan Block and central Yunnan Block. Under Tengchong block, there is a low resistivity zone in the crust with burial depth about 13~20 km and thickness about 10~17 km, which indicates there is magma chamber. Preliminarily, the ductile shear zone of Baoshan crust-mantle is taken as the deep east boundary of extrusion of the Indochina block.

关 键 词：滇西三江地区 大地电磁测深 电性结构 东边界 挤出块体 

分 类 号：P631[天文地球—地质矿产勘探]