Analysis on Sedimentary Facies in the Qixia Formation,Middle Permian at Huaying Xikou Section

Based on numerous previous researches and a lot of field surveys,the Qixia Formation of Middle Permian at Huaying Xikou section has been divided into two sections,with total thickness of 115.11 m.The rock types of this section are simple,dominated by limestones,with minor dolomites and siliceous rocks.The limestones can be further divided into bioclastic microcrystalline limestone,micritic limestone,microcrystalline bioclastic limestone and micritic bioclastic limestone.Based on the field section, microscopic analysis and a comprehensive analysis on the background of the regional deposition,it is believed that the depositional environment of the lower of the first section of Qixia Formation is upper part of deep ramp,the upper part is upper zone of shallow ramp,the top of the first section is lagoon face on restricted platform,the second section of Qixia formation is considered as open platform,including bioclastic beach microfacies and depression facies in platform.