Study on Sedimentary Facies of the Quaternary in Sanhu Area of Qaidam Basin

The Quaternary of the Sanhu area in Qaidam Basin is subdivided into 5 sequences from bottom to top.The comprehensive analysis of outcrop,core,drilling,logging,seismic and analysis testing data indicates that in the area are developed the facies types such as alluvial fan,fan delta,delta and lake facies,with the lake facies being predominant.The alluvial fan can be subdivided into three subfacies as root,middle part and extremity.The front is predominant in the fan delta and the delta.The lake facies can be subdivided into three subfacies as the shore lake,shallow lake and half-deep lake.In different sequence periods there are different scales of facies.Various facies distribute regularly in space.The alluvial fan and the fan delta facies develop in the southern slope and northern Yaba'er and Quanji areas.The delta facies develop in Yanhu and Qarhan areas.And other areas are all occupied by the lake facies.Each plane distribution of sedimentary facies in each sequence indicates that the depositional places of the half-deep lake and the depositional center have the migration trend from west to east.Finally,on the basis of the comprehensive analysis on various results,the sedimentary model in the studied area is built.And it is pointed that the favorable exploration regions in the studied area are located in Senan-Jinda area and the structure development zones in the northern slope such as Tuoxi,Taidong and Sedong uplifts.