四川盆地及其周缘五峰组-龙马溪组细粒沉积的层序地层与岩相特征

以四川盆地及其周缘五峰组-龙马溪组一段页岩为研究对象，通过对页岩气测录井资料及岩心和露头样品分析测试数据的对比分析，开展了层序地层划分与对比、岩相分类与识别、沉积微相-岩相分布规律研究。研究认为，五峰组-龙马溪组一段页岩可划分为3个三级层序（SQ1，SQ2和SQ3），细分为7个体系域，优质页岩主要分布于3个层序的海侵体系域（TST），其中SQ2-TST优质页岩发育范围最广，其岩相类型主要为富有机质硅质页岩、高有机质含灰硅质页岩和中-高有机质含硅粘土质页岩等。同时明确了不同类型无机矿物的区域分布规律，靠近川中古陆和黔北隆起区域碳酸盐矿物含量相对较高，随着水体深度的增加，碳酸盐矿物含量逐渐降低，生物成因石英含量逐渐增加。以SQ2-TST为例，以3种主要矿物（石英、粘土和碳酸盐）含量等值线图、总有机碳含量（TOC）等值线图为基础，结合地球化学参数（Th/U）和地层厚度等参数等值线图，编制了SQ2-TST沉积相-岩相平面分布图。四川盆地及其周缘SQ2-TST沉积时期，在川中古陆、黔北隆起和川北古陆周缘，主要发育中-低有机质粘土质页岩和中-低有机质含灰硅质粘土质页岩，在川中古陆与黔北隆起所围限的川南深水陆棚亚相区主要发育富有机质含灰硅质粘土质页岩，而涪陵地区向川东北延伸区域主要发育富有机质硅质页岩。

Sequence stratigraphy and lithofacies characteristics of fine-grained deposits of Wufeng-Longmaxi Formations in the Sichuan Basin and on its periphery

This paper takes the shale samples from the Wufeng Formation and the first member of Longmaxi Formation in the Sichuan Basin and its periphery as the research subject. Through the comparative analysis of drilling data， core and outcrop analysis， and test data， a study on the sequence stratigraphic division and correlation， lithofacies classification and identification， and sedimentary microfacies-lithofacies distribution of the rocks is carried out. The results show that the fine-grained deposits of study interval can be divided into three third-order sequences （SQ1， SQ2， and SQ3）， which are subdivided into seven systems tracts. High-quality shales are mainly distributed in the transgressive systems tracts （TST） of the three sequences， of which high-quality shales of SQ2-TST are the most widely distributed. The lithofacies are mainly organic siliceous shale， organic-rich limy siliceous shale， and medium-high organic siliceous argillaceous shale. The regional distribution of different types of inorganic minerals is clarified. The contents of carbonate minerals are relatively high near the central Sichuan paleo-high and northern Guizhou Uplift. With the increase of water depth， the contents of clay minerals and quartz minerals gradually increase. The sedimentary-lithofacies of SQ2-TST is mapped by using the contour maps of the content of three terminal principal minerals （quartz， clay， and carbonate） and the content of total organic carbon （TOC）， in combination with the contour maps of parameters such as geochemical parameters （Th/U） and isopachous maps. On the periphery of the central Sichuan paleo-high， central northern Guizhou paleo-high， and northern Sichuan paleo-high， medium-low organic argillaceous shales and medium-low organic limy siliceous argillaceous shales deposited. In the deep-water shelf of southern Sichuan Basin enclosed by the central Sichuan paleo-high and central northern Guizhou paleo-high， organic-rich limy siliceous argillaceous shales are mainly deposited. organic-rich siliceous shales are mainly developed in the Fuling area extending to the northeast of the Sichuan Basin.