Abstract:

The sedimental facies of 3 m thick around the roof and bottem of the green-bean rock（altered tuff）between the Early and Middle Triassic can bedivided into 9 kinds of rock association,belonging to 5 sedimental facies zones respectively in the Upper Yangtze Plat form and its adjacent areas.The westpart of the studied region is a extensive sabkha platform,the facies zones aredistributed in circles.The outer part is constituted by purphish red clastic rock and massive dolomite of the sabkha;the middle circle consists of striped dolomite and anhydrite rock,striped magnesite,anhydrite intercalated with nodular polyhalite of salt playa;the inner one is made up of striped argillaceous anhy-drite rock.The sedimental facies of the east part are distributed as parallelribbon,which consists of striped argillaceous anhydrite rock,lamellar mudstoneand marl of desiccation bay in the west side,and massive gypsum microdolomite,micrite intercalated with oolitic limestone,dolomite of sabkha salt marsh andshallow sea in the east side.δ¹³C-value indicates that negative abnormal region of low value corresponds to paleodepression within the platform,and is considered to be salt lake or saltswamp;the one of the high value is corresponding to sabkha salt marsh or saltflat of the paleo-uplift within the platform;the normal region is considered tobe the open sea of south Guizhou and west Yunnan Provinces.