天水地区大地电磁测量及深部电性结构

MT SURVEY AND DEEP ELECTRIC STRUCTURE IN TIANSHUI AREA

摘要:

天水地区的大地电磁测量结果表明,在43km左右的深度上普遍存在高导层,这可能是壳幔过渡带的反映。岩石圈厚度大约95-110km。在天水太京附近可能存在一条大型近东西向地壳-岩石圈构造带,在秦安以北的叶堡和陇城附近可能也存在一条近南北向的大型地壳-岩石圈构造带,它们都是不同构造单元的分界线。1654年天水8级大震可能与深部热异常引起的热应力有关。

Abstract:

The MT survey in Tianshui area shows that there is a high conductivity layer in the depth of 43 km,which may be the reflection of the crust-mantle transition zone. The lithospheric thickness is about 95-110 km. There might be a large crust-lithosphere tectonic zone nearly in EW direction around Taijing, Tianshui, and there might be also a large crust-lithosphere tectonic zone nearly in NS direction mear Yebu and Longcheng,Qin an,The two zones are all the boundary lines of different tectonic units.The Tianshui M8.0 earthquake in 1654 probably related to the thermal stress caused by the deep heat anomaly.