矿业科学学报2024，Vol.9Issue(3)：315-326,12.DOI:10.19606/j.cnki.jmst.2024.03.001
川东北地区陡山沱组页岩地球化学特征与古环境分析
Geochemical characteristics and paleoceanic environment analysis of black shale in Doushantuo Formation in northeastern Sichuan Basin
摘要
Abstract
The shale in Doushantuo Formation is the main source rock of the Ediacaran in Sichuan Basin and the major hydrocarbon source layer of the ancient marine strata for natural gas exploration in recent years.Forty-six samples were collected from two outcrops(Baibaoxi and Shiping)in Chengkou county in northeastern Sichuan Basin.We analyzed the change of the sedimentary environment of the Member Ⅱ and Ⅳ of Doushantuo Formation in terms of their organic geochemical characteristics(total organic carbon,rock pyrolysis,kerogen carbon isotopes)and element geochemical characteristics(major elements,trace elements and rare earth elements).Results show that the shale of Doushantuo Formation in northeastern Sichuan Basin exhibit a high abundance of organic matter,with TOC content ranging from 0.19％to 20.38％(mean value is 4.76％).The dominant type of organic matter is type Ⅰ kero-gen,and it has reached over-maturity stage.High 8Eu anomalies and abnormally richness in V,Mn,Mo,Ba and U elements of the black shale revealed strong hydrothermal action during this period.The distri-bution pattern of rare earth elements and various redox indexes indicated that the redox fluctuates re-peatedly under the conditions of anaerobic-anoxic-sulfidic environment during the depositional period of the Member Ⅱ.The water environment of Member Ⅳ changed from anoxic to anaerobic-sulfidic environ-ment.In general,the water connectivity of the basin is strong,the depositional rate is relative high.The nutrients carried by upwelling from hydrothermal sources proliferate productivity,which promotes the formation of organic shale.关键词
川东北/陡山沱组/黑色页岩/古海洋环境/有机质富集Key words
northeastern Sichuan Basin/Doushantuo Formation/black shale/palaeomarine environment/organic matter enrichment分类
矿业与冶金引用本文复制引用
郭楚媛,胡国艺,田连杰,李贤庆,郭谨豪,张天怡..川东北地区陡山沱组页岩地球化学特征与古环境分析[J].矿业科学学报,2024,9(3):315-326,12.基金项目
国家自然科学基金(U22B6002) （U22B6002）
中国石油科技项目(2021DJ0601) （2021DJ0601）
