Upper Southern Siltstones Of Lower Permian Strata And Sedimentary Facies Study

This article comprehensive use the theory and method of sequence stratigraphy, sedimentology and other disciplines, by comprehensive analysis of mud logging, logging, core, thin slice, this article give a depth study to low Permian strata and sedimentary facies features in southern part of central Sichuan.The research show:in the South Central Sichuan Basin, low Permian is divided into7third order sequences and2second order sequences, and stablish the corresponding relationship of lithostratigraphy and sequence stratigraphy. The Liangshan group for the sequence1(PSql); The Qixia group contains two third order sequences, they are sequence2(PSq2), sequence3(PSq3), sequence4(PSq4); The Maokou group is divided into three third order sequences, respectively is:sequence5(PSq5)、sequence6(PSq6)、sequence7(PSq7). Granular rock has apparent Layer allelism, sequence Ⅲ, Ⅳ(Qiyi A sub-group, Qier group) and sequence Ⅶ(Maoer C sub-group, Maosan group) is the main development period of granular rock, followed by the sequence Ⅱ(Qiyi B sub-group). granular rock contain bioclastic limestone, algal limestone and sand limestone. In addition, Qier group develop dolomite granular rock.The area of southern part of central Sichuan, The Liangshan group in low Permian strata has the characteristic of developing clastic littoral facies. Qixia-Maokou group mainly developed open platform facies and semi restricted platform facies in land surface sea carbonate rock, including inner platform beach, open sea, semi restricted lagoon and sea among beachs four subfacies, which include ten or more microfacies. on the basis of grainstone, the ratio of single factor map from grainstone/strata thickness, we give the the planar facies analysis of all purpose layer section, and point out that the first section of Qixia group grainstone beach is mainly developed in Anping1well、Tong4well and Nvshen5well area; the seond section of Qixia group grainstone beach is mainly developed in Huaxi1well-Lai1well area and northern Baolong1well area; the second section of Maokou group grainstone beach is mainly developed in Moshen1well、Gaoke1well、Guangshen1well、 Guangcan2well、Guang3well and Hechuan12well area; the third section of Maokou group grainstone beach is mainly developed in Lai1well area and the east zone of Guangcan2well.