| 藏北高原地壳及上地幔导电性结构——超宽频带大地电磁测深研究结果 |
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| 引用本文： | 魏文博,金胜,叶高峰,邓明,谭捍东,Martyn Unsworth,Alan G.Jones,John Booker,Shenghui Li.藏北高原地壳及上地幔导电性结构——超宽频带大地电磁测深研究结果[J].地球物理学报,2006,49(4):1215-1225. |
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| 作者姓名： | 魏文博 金胜 叶高峰 邓明 谭捍东 Martyn Unsworth Alan G.Jones John Booker Shenghui Li |
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| 作者单位： | 1.地质过程与矿产资源国家重点实验室和地下信息探测技术与仪器教育部重点实验室，北京 100083 2 中国地质大学(北京)地球物理与信息技术学院，北京 100083 3 University of Alberta, Edmonton, Canada 4 Dublin Institute of Advanced Studies, Dublin, Ireland 5 University of Washington, Seattle, USA |
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| 基金项目： | 教育部重大项目（重大0211）资助,国土资源部“十·五”青藏专项研究计划项目（2001010202）资助. |
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| 摘 要： | 为了研究西藏中、北部壳、幔导电性结构，讨论高原中、北部岩石圈热状态，1998年和1999年（INDEPTH（Ⅲ） MT）在西藏中、北部完成了德庆—龙尾错（500线）和那曲—格尔木（600线）超宽频带大地电磁深探测剖面的研究.研究结果表明，西藏中、北部以昆仑山断裂为界，其南北壳、幔电性结构有很大差异.昆仑山断裂以北地壳和上地幔为高阻区.而昆仑山以南，地壳和上地幔的导电性有明显的分层结构：地壳上部以不连续的高阻体为主，夹有局部低阻异常体，沿南北方向上地壳的电性结构复杂，具有不连续、分块的特点；但中、下地壳为大范围的高导异常区，区内发育有大规模、不相连续、产状各异的高导体，其电阻率均小于4Ωm；在班公—怒江和金沙江缝合带之下，壳内高导体都具有向上地幔延伸的趋势，存在连通壳、幔的低阻通道.根据西藏高原中、北部壳、幔电性结构的研究推断：如同藏南一样，这里也普遍存在部分熔融体和热流体，它们的成因主要与班公—怒江和金沙江缝合带的壳-幔热交换、热活动有关，这是两期形成的壳-幔热交换通道.其中，班公—怒江缝合带的壳-幔热交换通道形成时间比金沙江缝合带早.因此，研究区壳、幔的热活动是从南边和西边开始，向北、向东扩展，导致现今西藏中、北部地壳和上地幔的热流分布由西向东、由南向北增大.
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| 关 键 词： | INDEPTH MT 大地电磁探测 壳内高导体 壳-幔热交换 |
| 文章编号： | 0001-5733（2006）04-1215-11 |
| 收稿时间： | 2005-9-13 |
| 修稿时间： | 2005-09-132006-03-31 |
Conductivity structure of crust and upper mantle beneath the northern Tibetan Plateau: Results of super-wide band magnetotelluric sounding |
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| WEI Wen-Bo,JIN Sheng,YE Gao-Feng,DENG Ming,TAN Han-Dong,Martyn Unsworth,Alan G.Jones,John Booker,Shenghui Li.Conductivity structure of crust and upper mantle beneath the northern Tibetan Plateau: Results of super-wide band magnetotelluric sounding[J].Chinese Journal of Geophysics,2006,49(4):1215-1225. |
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| Authors: | WEI Wen-Bo JIN Sheng YE Gao-Feng DENG Ming TAN Han-Dong Martyn Unsworth Alan GJones John Booker Shenghui Li |
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| Institution: | 1.State Key Laboratory of Geological processes and Mineral Resources and Geo detection Laboratory ,Ministry of Education, Beijing 100083, China 2 School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China 3 University of Alberta,Edmonton, Canada 4 Dublin Institute of Advanced Studies, Dublin, Ireland 5 University of Washington, Seattle, USA |
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| Abstract: | To study the resistivity structure of crust and upper mantle beneath northern and central Tibet, furthermore, discuss thermal behavior of north and central Tibet lithosphere, super wide band magnetotelluric sounding profiles named line 500 and line 600 which belongs to INDEPTH(Ⅲ) were finished in 1998 and 1999. The line 500 is from Dêqên to Longwei Co, and the line 600 is from Nagqu to Golmud. The results show that the boundary between northern Tibet and central Tibet is Kunlun fault, and the conductive structures of crust and mantle beneath northern and central Tibet are very different. North to the Kunlun fault the crust and upper mantle are resistive. But south to the Kunlun fault, the conductive structure of crust and upper mantle is in layers: in the upper crust, there are lots of discontinuous resistive bodies, and between them are local conductive bodies. From south to north the conductive structure of the upper crust is very complex and discontinuous, while the middle and lower crust is very conductive. There are lots of continuous, huge conductive bodies with different shapes, and their resistivities are all smaller than 4Ωm. Below the Bangong Nujiang suture and Jinsha suture, the conductive bodies in the crust stretch into upper mantle, so they are conductive channels which connect crust and mantle. In northern and central Tibet there are also partial melted bodies ubiquitously related with heat transmission between crust and mantle below the Bangong Nujiang suture and Jinsha suture, which formed in different stages. Moreover, the heat transmission channel between crust and mantle below the Bangong Nujiang suture is older than that of the Jinsha suture. Therefore, heat activity in crust and mantle of Tibet began from south and west, spreading to north and east, which made the heat flow of crust and upper mantle of northern and central Tibet increase from west to east and from south to north. |
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| Keywords: | INDEPTH-MT Magnetotelluric sounding Conductive bodies in crust Heat transmission betweencrust and mantle |
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