THE CHARACTERISTICS AND EVOLUTION OF MESOCENOZOIC CONTINENTAL DOWNWARPED AND DOWN-FAULTED BASINS IN ANHUI PROVINCE

The Early Jurassic,Early Cretaceous,latest Cretaceous and late Tertiary were the most important periods of development and transformation of the Meso—Cenozoic continental downwarped and down-faulfed basins.The generation and development of the basins exhibited the multi-stage nature,which may be summarized as follows:the Early-Middle Jurassic were the period of the formation,the Late Jurassic-early Late Cretaceous were the period of their formation and development,the latest Cretaceous-early Tertiary were the period of culmination of their development,and the late Tertiary-Quaternary were the period of their decline.The basins were mainly controlled by the marginal-Pacific tectonic domain and secondarily by the near-E-W-trending faults.The development of the basins was closely related to the structure of their basement.If the basement was highly rigidified,the form of the basins would be regular and well closed;on the contrary,their form would be highly varied and poorly closed.