Research on Sedimentary Facies of the Upper Ganchaigou Formation in the Southwestern Qaidam Basin

Sedimentary facies of the upper Ganchaigou Formation in the southwestern Qaidam Basin is studied based on the analysis for a lot of drilling,logging profiles and phase marks,combined with previous research results.Studies show that lake facies,braided river delta and lake floor fan facies developed in the study area,in which the shallow lake subfacies is the main type which is composed of shallow lake sandbar,shallow lake mud,shallow lake plaster,algal limestone,shallow lake oolitic bank and storm deposit..The main type of braided river delta is braided delta front subfacices which can be further divided into the underwater distributary channel,underwater natural barrier,the tributary bay and mouth bar microfacies.Sublacustrine fan facies mainly developed in Qige-Quan area,including typical turbidite strata sequence.