Abstract: The carbonate rocks of the Upper Carboniferous Chuanshan Formation in the Jurong area consist mainly of cryptite, fine crystalline limestone, bioclastic cryptite, micrite bioclastic limestone, clastizoic cryptite and clastizoic oncolite limestone, in which several platform carbonate depositional facies, including tidal flat, open platform, platformal trough, shoalreef and organic reef, can be identified. The carbonate succession of the Chuanshan Formation is composed of three thirdorder deposition sequences: TypeⅠ sequence S1, and TypeⅡ sequences S2 and S3. Based on lithology, sedimentary facies, paleontology and geochemistry characteristics, the relative sealevel change curve was established, indicating there were three relative sealevel changes during the evolution of the Chuanshan Formation. These relative sea level changes controlled the development of sequences. S1 comprises the lowstand systems tract (LST) of conglomerate of shore limestone and crystalline limestone of tidal flat, transgressive systems tract (TST) of clastizoic cryptite and cryptite developed in platformal trough, and highstand systems tract (HST) of clastizoic oncolite limestone developed in shoal. S2 is made of TST of micrite bioclastic limestone in reef, bioclastic cryptite, clastizoic cryptite and cryptite in open platform, and HST of clastizoic cryptite in open platform. S3 composes TST of cryptite in open platform, HST of clastizoic oncolite limestone in shoal, and crystalline and clumpy limestones in tidal flat. In general, the carbonate platform of the Chuanshan Formation in the Lower Yangtze region developed in a shallow environment with relatively stable tectonic background; there also existed shoal and trough in the platform. Limestones in the open platform and platformal trough are highquality source rocks while shoal reef limestones are good reservoir rocks.

Key words:  Lower Yangtze region, Chuanshan Formation, Jurong, carbonate rock, sedimentary facies, sequence, relative sea level change