四川广安市响水飞仙关组剖面特征及地质意义

四川省广安市桂兴镇响水村下三叠统飞仙关组地质剖面,位于华蓥山背斜的西翼,其古地理位置位于早三叠世川东碳酸盐台地西侧。对该剖面的详细研究,有利于恢复飞仙关期川东碳酸盐台地西侧的沉积演化过程。响水剖面飞仙关组一段属于半局限浅海陆棚和开阔台地含泥灰岩沉积。飞仙关组二段下部为碳酸盐台地西缘斜坡相及开阔台地相;其上部为较稳定的开阔台地沉积。飞仙关组三段是碳酸盐台缘鲕滩和开阔台地沉积。飞仙关组四段属于典型的混积台地潮坪沉积。川东碳酸盐台地西侧飞仙关组由两个向上变浅的沉积旋回组成,第2个沉积旋回是碳酸盐台地向西增生和鲕滩发育的主要时期。

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

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.