湖北兴山大峡口中-上二叠统沉积与演化特征

Sedimentary facies characteristics and evolution of Middle and Upper Permian in Daxiakou section of Xingshan County,Hubei Province

湖北省兴山大峡口地区,中-上二叠统出露良好,特征明显,详细的野外剖面测量和室内微相分析表明,此剖面岩相主要由生物碎屑颗粒灰岩、泥晶灰岩、砂屑灰岩、砾屑灰岩、硅质岩等组成,文章就岩相与沉积相的关系做了详细论述。沉积相分析表明,中二叠统主要为碳酸盐斜坡沉积,上二叠统主要为台地沉积,其次为滨岸和盆地沉积,中二叠世和晚二叠世分别构成2个大的海侵海退旋回,呈现出持续稳定沉降的局面。

Middle and Upper Permian in Daxiakou section of Xingshan County,Hubei Province is well exposed and has obvious characteristics.According to the strata study of the field outcrops and the laboratory microfacies study of marine carbonate,five kinds of lithofacies can be recognized including bioclastic grainstone,mudstone,micrite calcisiltite,bcalcirud and silica.The relationship between lithofacies and sedimentary facies is also studied.The results of sedimentary facies analysis show that Middle Permian mainly deposits on the carbonate slope,and Upper Permian mainly on the carbonate platform.The coastal and basin sediments are in the second place.The sedimentary evolution indicates that two sedimentary cycles of transgression and regression occur in the Middle Permian and Upper Permian respectively,and the subsidence is continued,widespread and stable.