重庆云阳石梁飞仙关组剖面特征及地质意义

重庆云阳石梁剖面位于上扬子板块北缘南大巴山冲断带位置，早三叠世飞仙关期处于城口-鄂西海槽西侧位置，对该剖面的详细研究，有利于恢复飞仙关期川东北碳酸盐台地东缘的沉积演化过程．研究认为，该剖面飞仙关组-段属于斜坡相沉积；二段下部继承碳酸盐台地东缘斜坡相，中部发育典型的台地边缘滩沉积，其顶部则演化为局限台地溺湖环境；三段由开阔台地及局限台地渴湖沉积构成；四段属于典型的局限台地潮坪沉积城口-鄂西海槽西侧飞仙关组由两个向上变浅的沉积旋回组成，通过与相邻位置的井剖面对比认为。相对海平面变化控制了城口-一西海槽西侧飞仙关期沉积相演化。台地边缘滩基本发育于相对海平面下降时期

Characteristics of the Section of the Feixianguan Formation at Shiliang,Yunyang, Chongqing,and Their Geological Significance

The geological section at Shiliang, Yunyang, Chongqing, is located on the southern Dabashan thrust belt on the northern margin of the upper Yangtze plate, and was located on the western side of the Early Triassic Chengkou-Western Hubei trough. Study of this section in detail is favorable to the reconstruction of the sedimentary history of the eastern side of the carbonate platform in northeast Sichuan Basin. Based on the measured section, the First Member of the Feixianguan Formation consists of slope facies. The lower part of the Second Member of the Feixianguan Formation consists of the slope facies on the eastern margin of the carbonate platform facies with shoal on edge of platform in the middle and restricted platform lagoon deposits in the top. The Third Member consists of open platform and restricted platform lagoon deposits, and the Fourth Member of belongs to restricted platform tidal fiat deposits. The Feixianguan Formation on the western side of Chengkou-west Hubei trough comprises two ascendingly shallowing depositional cycles. The results of section correlation show that the relative changes of sea level has obvious controlling effect over the evolution of sedimentary facies of the Feixianguan Formation. The shoal on edge of platform was almost developed in the sea level fall period.