桂中坳陷中北部下石炭统寺门组层序与沉积相分析

通过对桂中坳陷中北部下石炭统寺门组水源塘现剖面、中渡长盛剖面等20条野外露头剖面和东塘1井等钻井岩心资料的详细观察,结合岩石薄片、粒度分析及前人研究等资料,对研究区寺门组碎屑岩沉积相类型及沉积演化特征进行了深入研究。研究表明:①桂中坳陷中北部寺门组可划分出1个三级旋回,4个四级旋回。②寺门组广泛发育碎屑滨岸相沉积,发育潮坪亚相沉积,局部地区发育有泻湖亚相沉积。砂坪微相沉积主要发育在环江以北、柳州以东地区,混积坪微相全区较为发育;泥坪微相主要发育在南丹以西、宜州周缘、柳城以北和象州周缘等地;泻湖亚相主要发育在柳州地区。③下石炭统晚期研究区寺门组发育一种沉积模式,区内广泛发育滨岸相。研究结果揭示研究区寺门组沉积演变规律,为油气资源勘探提供地质依据。

Analysis of Sequence and Sedimentary Facies in Simen Formationin of Lower Carboniferous in the North-central Guizhong Depression

Based on the detailed observation of 20 field outcrop profiles of Shuiyuan Tangxian bisect and Zhongdu Changsheng bisect,and the data of the borehole of Dongtang 1 in the north-central Guizhong depression,this paper,combined with the data of rock sheet,granularity analysis and previous studies,researches the types and its evolution characteristics of the clastic rocks sedimentary facies in the research area.The results show that:①The Simen formation can be divided into one third-order cycles of sedimentation and four fourth-order cycles of sedimentation in the north-central Guizhong depression.②Clastic onshore-tidal flat deposits are widely developed in the Simen formation.There are some lagoon microfacies deposits in some areas.The Shaping microsedimentary deposits are mainly developed in the north of Huanjiang and east of Liuzhou.The microfacies of the Hunjiping is more developed in the whole area.The Niping microfacies is mainly developed in the west of Nandan,the periphery of Yizhou,the north of Liucheng and the edge of Xiangzhou.③In the late Lower Carboniferous,a sedimentary model has been developed in Simen formation of the study area,the onshore-tidal flat phase being widely developed.The above studies revealed the sedimentary evolution rule of Simen formation and meanwhile provided a geological basis for oil-gas exploration.