Analysis on Geothermal Geological Condition of Xining Basin on the Basis of Characteristic of Geophysical Field

Based on the comprehensive explanation of controllable source audio frequency geo-magnetic sounding and previous geophysical prospecting data as gravity,earthquake,geo-magnetic sounding and direct current electric sounding,the tectonic framework of uplift with depression and features of Xining basin are obtained.According to distribution character of geothermal field,the geothermal reservoir type of Xining basin is discussed.It is indicated that the Xining depression in Xining basin is extensional and transtensile fault depression,characterized by higher geothermal field and geothermal gradient,it has both geothermal reservoir of fracture convection type and basin conduction type.While Datong and Pingan depression in Xining basin are compress-shear depressions,characterized by lower geothermal field and geothermal gradient,with reservior of basin conduction type.Xining depression is a favourable exploring region for geothermal resource.