叶涛^1,,
黄清华^1,,,
陈小斌²
1. 北京大学地球物理学系, 北京 100871
2. 中国地震局地质研究所地震动力学重点实验室, 北京 100029

基金项目: 国家自然科学基金（41574104，41661134014）以及国家喜马拉雅计划地震专项（201108001）联合资助


详细信息

作者简介: 叶涛, 男, 1989年生, 博士.研究方向为地球深部电性结构研究.E-mail:yetao@pku.edu.cn

通讯作者: 黄清华, 男, 教授, 1990年毕业于中国科学技术大学, 1999年获日本大阪大学博士学位, 主要从事地球电磁学、地震物理学方面的教学与科研工作.E-mail:huangq@pku.edu.cn

中图分类号: P319;P541

收稿日期:2018-05-15
修回日期:2018-08-06
上线日期:2018-11-05

Three-dimensional deep electrical structure and seismogenic environment of Nantinghe fault zone in southwestern Yunnan, China

YE Tao^1,,
HUANG QingHua^1,,,
CHEN XiaoBin²
1. Department of Geophysics, Peking University, Beijing 100871, China
2. Institute of Geology, China Earthquake Administration, Beijing 100029, China


More Information

Corresponding author: HUANG QingHua,E-mail:huangq@pku.edu.cn

MSC: P319;P541

--> Received Date: 15 May 2018
Revised Date: 06 August 2018
Available Online: 05 November 2018


摘要
摘要:南汀河断裂带为滇西南地区活动断裂体系中规模最大的一条北东向断裂，其构造活动及地震危险性一直备受关注.本文基于覆盖云南境内南汀河断裂带的大地电磁测深宽频带阵列数据，利用大地电磁三维反演解释技术，首次获得了南汀河断裂带的精细三维深部电性结构.在上地壳深度，南汀河断裂带西南段与中段的电性结构表现出沿构造走向的高导条带特征，北东段表现为高阻结构.该高阻结构可能为临沧—勐海花岗岩体的电性反映，指示南汀河断裂可能未切穿该花岗岩带.在中下地壳深度，南汀河断裂带西南段存在大范围高导层，北东段则表现为整体性的高阻地壳，因此南汀河断裂北东段可能具有发生强震的介质结构背景.南汀河断裂带西南段的耿马地震区深部呈现北东向与北北西向的"X"型高导构造样式，该高导结构以南存在一个显著高阻异常体，1988年耿马M_S7.2地震以及2015年沧源M_S5.5级地震均发生于该高阻体与"X"型高导条带的电性边界.青藏高原东南缘绕东构造结流入滇西地区的中下地壳流可能受到南汀河断裂北东段中下地壳高阻体的阻挡而呈分流式分布于保山地块以及澜沧江断裂以东.
关键词: 南汀河断裂带/
大地电磁测深(MT)/
2015沧源地震/
1988耿马地震/
中下地壳流

Abstract:The Nantinghe fault zone is the largest northeast-trending fault of the active fault system in southwestern Yunnan. Its tectonic activity and seismic hazard have attracted much attention. Based on broadband magnetotelluric array data covering the Nantinghe fault zone in Yunnan, this paper obtained the fine three-dimensional electrical structure of the Nantinghe fault zone using three-dimensional MT inversion interpretation. In the upper crust, the southwestern and middle segments of the Nantinghe fault zone show the feature of banded conductive structure along the strike direction, while the northeastern segment exhibits high resistive feature. The electrical resistive feature of the northeastern section may be a reflection of the electrical property of the Lincang-Menghai granite, indicating that the Nantinghe fault may not cut through the granite belt. In the mid-lower crust, there is a large-scale high conductivity layer in the southwestern segment of the Nantinghe fault zone, while the northeastern segment presents an overall resistive crust. Therefore, the northeastern segment of the Nantinghe fault has potential seismogenic background of a strong earthquake. In the southwestern Nantinghe fault zone, the deep part of the Gengma earthquake zone presents an X-shaped high-conductivity pattern. There is a significant resistive anomaly to the south of the above X-shaped high-conductivity structure. The 1988 Gengma M_S7.2 earthquake and the 2015 Cangyuan M_S5.5 earthquake both occurred at the electrical boundaries between the high resistivity body and the X-shaped high-conductivity structure. The branch of mid-lower crust channel flow, which flows from the southeastern margin of the Tibetan Plateau into western Yunnan, may be blocked by the mid-lower crustal resistive body in the northeastern Nantinghe fault, and bifurcated into the Baoshan block and the eastern Langcanjiang fault.
Key words:Nantinghe fault/
Magnetotelluric (MT)/
2015 Cangyuan earthquake/
1988 Gengma earthquake/
Mid-lower crust channel flow



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