Abstract: Permian to lower Triassic isolated carbonate platform depositional systems in Pingguo area is studed in detail in this thesis. Permian sedimentary facies of Pingguo ancient carbonate platform can be divided into carbonate platform center facies; platform margin facies and platform slop-trough facies, and lower Triassic sedimentary facies can be divided into carbonate platform facies area and classic trough facies area. Petrological and paleobiological characteristics of these facies are described and the original of various scdiments is analysed.Some problems about their distribution,tectonic control and sedimentation are discussed.According to the viewpoint of system theory,the difference between platform facies and trough facies,and the influence among them are summerized,and their evolution model is found in this paper.

Key words: Depositional facies, Ancient geography, Permian to lower Triassic, Pingguo area of Guangxi