重庆石柱中上二叠统沉积特征与层序地层

Sedimentary characteristics and sequence stratigraphy of the Middle-Upper Permian in Shizhu,Chongqing,China

重庆石柱地区中上二叠统碳酸盐岩发育。在野外实测及室内微观研究的基础上,详细分析了该区的沉积特征,并进行层序地层分析。结果表明,重庆石柱中上二叠统发育于滨岸、碳酸盐缓坡、碳酸盐台地和台盆四种沉积环境中,其中滨岸发育于吴家坪组底部,碳酸盐缓坡发育于吴家坪组中下部,碳酸盐台地发育于茅口组和长兴组,台盆发育于茅口组上部和吴家坪组的中上部。研究区中二叠统茅口组-上二叠统长兴组可划分为8个三级层序,其底界面类型多为Ⅱ型层序界面,多缺少SMST体系域;受东吴运动的影响,PSQ4底界面为Ⅰ型层序界面,为升隆侵蚀不整合界面,并发育了LST体系域。研究区台盆相的发育受控于华南大陆板块内部强烈的板内裂谷(裂陷)作用,其边缘为油气勘探的有利区块。

The marine stratigraphy is a key to the oil and gas exploration today in east of Sichuan Basin. Many research results show that the oil and gas reservoirs are located in bioherms and shoals on platform margins, which control the distribution of reservoir. Many types of carbonate rocks deposited in the Middle-Upper Permian of Shizhu of Chongqing belonging to the east of Sichuan Basin. Based on the field sections and microscope researches, the authors analyze the sedimentary characteristics and sequence stratigraphy of the Middle-Upper Permian. The results show that the Middle and Upper Permian have mainly deposited on the coast reefs, carbonate ramps, carbonate platforms and inter-platform basins. And coast reefs have developed on the bottom of the Wujiaping Formation, carbonate ramps on the lower part of the Wujiaping Formation, carbonate platform in the Maokou Formation and the Changxing Formation, and inter-platform basins on the upper part of the Maokou Formation and the Wujiaping Formation. The Middle-Upper Permian are divided into eight sequences. There have almost developed Type Ⅱ sequence boundaries and are lack of SMST （Shelf Margin Systems Tract）. With the influence of the Dongwu Movement, there have deposited Type Ⅰ sequence boundary and LST in PSQ4. It is implied that inter-platform basins are controlled by the intraplate rifting of South China. And available blocks of reservoirs are located the around interplatform basins.