地质学报2018，Vol.92Issue(2)：215-231,17.
西藏那曲大地电磁数据反演与电性结构分析
Magnetotelluric Data Inversion and Conductivity Structure Analysis in Naqu, Tibet
摘要
Abstract
Tibet is located in the Qinghai-Tibet Plateau and characterized by complex geological structure and new intense tectonic activities.Tibet hosts abundant geothermal resources,ranking the first in national reserves of geothermal resources identified.The Qinghai-Tibet Plateau undergoes frequent tectonic activities due to strong north-south extrusion.Change of geological stresses resulted in formation of a series of structural belts.The observation station in Naqu of Tibet is placed on the secondary tectonic belt of Bangongcuo-Nujiang deep faulting in the northern part of Tibet,which are controlled by both near-NW-trending faulting and NS-trending faulting.Existing data show that new tectonic movement in the observation area was active,manifesting that the deep huge faulting is still active.To study the deep electric structure of the observation area,three magnetotelluric profiles were investigated to analyze spatial distribution features and formation mechanism of geothermal resources.The shallow strata of observation area are mainly presented by 1D/2D structure and deep strata by 2D/3D structure.2D and 3D magnetotelluric data inversion were also performed,yielding 2D and 3D electric models of for 3-km-deep shallow strata.This study carried out 2D magnetotelluric inversion using continuous media inversion method and 3D magnetotelluric inversion using REBOCC 3D inversion code,and comprehensively interpreted 2D and 3D electric structures based on hydrogeological investigation results.Research results show that horizontal electrical gradient belt of 2D geoelectric structure in the observation area reflects a fault,with distinct feature of vertical layering;low resistance layers in the high resistance layers reflect a deep complex structure in the observation area;local high resistance bodies of 3D geoelectric structure represent active range of intrusive rocks and low resistance area reflects spatial distribution of geothermal resources in the observation area.Geothermal resources results from infiltration of surface rivers along secondary fractures,and therefore,geothermal activities are controlled by faulting structure.关键词
西藏/地热/大地电磁/二维反演/三维反演/电性结构Key words
Tibet/geothermal/magnetotellurics/2D inversion/3D inversion/conductivity structures引用本文复制引用
徐志敏,汤井田,辛会翠,李晋,周聪,王显莹..西藏那曲大地电磁数据反演与电性结构分析[J].地质学报,2018,92(2):215-231,17.基金项目
本文为国家自然科学基金(41404111)、国家自然科学基金(41174105)和湖南省自然科学基金(2015JJ3088)联合资助的成果. （41404111）
