Abstract:

Based on the study of oceanic array magnetotelluric sounding data and the data of geophysical survey and well log,the geological texture and structural property of the beach area in Liaodong Bay were analysed with 2-D finite element method.The results indicate that Tanlu fault zone caused considerable effect on the area.The fault zone has four big fractures in Liaodong Bay,the Ejiegou-Jiezhoutan fracture among them cut deep into the crystal palaeobasement;another fracture,Dawa-Nanhai fracture,controlled the distribution of the Middle and Upper Proterozoic.The Middle and Upper Proterozoic were confined within the two sides of the fracture.What's more,as a whole,Tanlu fault also controlled the distribution of Mesozoic volcanic rocks,the volcanic rocks on the west side of the fault developed well than that on the east side.Besides,the superiority of great depth of electromagnetic sounding was also used to probe the deep texture of the globe.The result suggests that the depth of high conductive layer of the mantle is about 60 km,and that the undulation of the asthenosphere show distinct mirror relation;the depth of intracrustal high conductive layer is about 20 km.This is the reflection of detachment zone formed in earth crustal extension.

Key words: oceamic array magnitotelluric sounding, intracrutal high conductive layer, intramantle high conductive layer, principal fracture