Characteristics of the section of the Feixianguan Formation at Xiangshui Village, Guang'an, Sichuan, and its geological significance

Abstract：The geological section of the Lower Triassic Feixianguan Formation at Xiangshui Village, Guang'an City, Sichuan Province, is tectonically located in the western limb of the Huaying Mountain anticline and was paleogeographically located on the western side of the Early Triassic eastern Sichuan carbonate platform. Studying this section in detail is favorable to the reconstruction of the sedimentary history of the western side of the carbonate platform. The First Member of the Feixianguan Formation consists of semi-restricted neritic shelf facies and open platform facies deposits with marlstone. The lower part of the Second Member of the Feixianguan Formation is slope facies on the western margin of carbonate platform facies and open platform facies, while its upper part is relatively stable open platform deposits. The Third Member of the Feixianguan Formation consists of oolitic bank and open platform deposits, and the Fourth Member of the Feixianguan Formation belongs to diamictic tidal flat deposits. The Feixianguan Formation on the western side of the eastern Sichuan carbonate platform comprises two upward-shallowing depositional cycles. The second depositional cycle was the main period of westward accretion of the carbonate platform and development of oolitic banks.