Combination regularities of reef-beach and main controlling factors in Changxing-Feixianguan Formation of eastern Sichuan-northern Chongqing area

Key words:  eastern Sichuan-northern Chongqing area  Changxing Formation  Feixianguan Formation  reef-beach combination  controlling factors

Abstract:

Based on the analyses of important profile, drilling data and seismic facies of the eastern Sichuan-northern Chongqing area, and by combining with the identification of rock thin sections and the sedimentary facies signatures of petrologyand paleontology, the combination regularities of reef(beach)-beach and main controlling factors of the Upper Permian Changxing Formation-Lower Triassic Feixianguan Formation in the eastern Sichuan-northern Chongqing area are dissected in detail. The study area is divided into two types of complete reef-beach combination and incomplete reef-beach combination,and the two combination types are subdivided into five secondary combination types.Among them, the complete combination of the reef(beach)in Changxing Formation and the beach in Feixianguan Formation has more reservoir significance. In particular, the platform margin reef in Changxing Formation and the platform margin beach in Feixianguan Formation combination has the strongest dolomitization in the reef and beach crest, where the reservoir is most developed. The development type of reef-beach combination is usually controlled by sedimentary environment evolution, sea-level fluctuation, and paleo-tectonics.