玛曲—北川MT大剖面及川西北地壳结构初探

Maqu-Beichuan MT Profiling and Preliminary Investigation of Crustal Structure in Northwest Sichuan,China

摘要:

通过玛曲-北川MT勘探大剖面,揭示了沿线上地壳、下地壳、上地幔的空间展布与构造特征。认为上地壳盖层与基底之间存在一个自华北地块向龙门山方向的巨型推覆构造;上地壳,尤其是结晶基底的厚度制约了地块的稳定性;壳内低阻层起伏、莫霍面的隆坳与地块的稳定性相关。

Abstract:

The Magnetotelluric exploration profile of Maqu-Beichuan shows the extent and structure characters of upper crust,lower crust and upper mantle along the sections.First,there exists a large nappe structure from north China block to Longmenshan tectonic belt between the overlying strata of upper crust and basement.Second,the thickness of upper crust,especially the one of crystalline basement,limits the stability of blocks.Third,the relief of low-resistivity layer in the crust and the swell or sag of Moho are close correlative to the stability of blocks.