SEDIMENTARYFACIES ON THE UPPER PALEOZOIC OFTHE ORELAND BASIN OF THE WESTERN MARGIN OF THE ORDOS, INJIANG

Analysis of sedimentary facies was carried out on the Paleozoic along the overthrusting structure zone of the western margin of the Ordos. Six sedimentary facies had developed in the area.: carbonate tidal-flat sedimentary facies, sand barrier-lagoon facies, estuarine facies, fluvial facies, lake facies and delta facies. According to the five second-order sequences identified in the Upper Paleozoic, the distribution of these sedimentary facies has been a subject of great speculation. This paper summarizes the sedimentary evolution of the basin. It developed in three stages: filling of rift. , filling of epiric sea and filling of continental downwarping due to the reactivation of the aulacogen. The controlling factors of sedimentary facies evolution in this area have been analyzed in relation to structure, source supply, marine transgression, and paleoclimate.