Lacustrine carbonate rocks of the Paleogeneand Neogene in western Qaidam Basin are mainly distributed from the upper member of the Xiaganchaigou Formation to Youshashan Formation,and more developed in the  upper member of the Xiaganchaigou Formation and Shangganchaigou Formation There are three types of carbonate rocks,including  micrite limestones,algal limestones and grain limestones in western Qaidam BasinThe diamictites resulting from the mixing of lime,dolomite and terrigenous clastics are widely distributed Carbonate sedimentary facies include lime mud flats and algal flats in littoral lake,grain banks in shallow lake,algal mounds in shallow lake and marls in semideep lakeetc The typesof carbonate rocks of limemud flats in littoral lake mainly include micritic limestones,micrite limestones with terrigenous clastics and marls with terrestrial clasticsetc Those of algal flats in littoral lake mainly include algal micrite limestones and algal laminar limestones and algal micrite limestoneswith terrestrial clasticsThose of grain banks in shallow lake mainly include ooid limestones with spar or micrite,bioclastic limestones,intraclastic limestones and grain limestones Those of algal mounds in shallow lake mainly include algal stromatolitic limestones, algal clast limestones, algal micrite limestones and algalmicrite limestones with terrestrial clastics Those of marls facies in deep lake mainly include micrite limestones, marls, micrite limestones or marls with little mud and silt Carbonate sedimentary facies show a strong migration trend from southwest to northeast