Electrical resistivity structure of Longmenshan crust-mantle under sector boundary
Electrical resistivity structure of Longmenshan crust-mantle under sector boundary
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发表时间：
2013
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通讯作者：
Wang Xu
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作者：
Wang Xu
为研究龙门山及邻区壳幔电阻率结构，完成了一条沿着碌曲-龙门山-合川的长周期大地电磁剖面，采用了系统合理的扇形边界下二维反演算法，该剖面的结果显示出龙门山如尔盖壳幔高阻带，龙门山壳幔高阻块体在龙门山逆冲带之下呈向北西伸展的楔形高阻块体，由于龙门山壳幔高阻块体的双阻作用，龙门山壳幔高阻块体在龙门山逆冲带之下呈向北西伸展的楔形高阻块体。青藏高原东缘和上扬子板块的定向挤压作用，松潘-甘孜造山带的地壳物质向龙门山逆冲，中下地壳和上地幔向西南方向滑动，上扬子板块西缘呈楔形插入青海东缘，松潘壳幔韧性剪切带最初被认为是中新生代以来上扬子板块西缘深部边界。
A long peroid magnetotelluric profile along the Luqu-Longmenshan-Hechuan has been finished which helps to study the crust-mantle electrical resisitivity structure in Longmenshan and its adjacent area,Institutive and reasonable 2-D inversion algorithm under sector boundary was adopted.The results of this profile has shown the crust-mantle high resistance belt in Ruergai,Longmenshan,central Sichuan and low resistance belt in Songpan from northwest to southeast.Longmenshan crust-mantle high resistance block shows up as wedge-shaped high resistance block stretching to northwest under the Longmenshan thrust belt.Due to bi-directional compression of East margin of Qinghai-Tibet plateau and upper Yangtze plate,Crust materials of Songpan-Ganzi massifs thrust to Longmenshan,and middle-lower crust and upper mantle slides toward southwest,presenting a trend that west margin of upper Yangtze plate in shape of wedge inserting into east brim of Qinghai-Tibet Plateau.It was initially thought that Songpan crust-mantle ductile shear belt is regarded as the west margin deep boundary of upper Yangtze plate since Mesozoic-Cenozoic Era.