天然气勘探与开发2025，Vol.48Issue(3)：1-13,13.DOI:10.12055/gaskk.issn.1673-3177.2025.03.001
川北地区陡山沱组烃源岩地球化学特征与沉积环境
Geochemical characteristics and sedimentary environment in source rocks of Doushantuo Formation,northern Sichuan Basin
摘要
Abstract
That some strategic breakthroughs in natural-gas exploration have been made recently in the Upper Sinian Dengying Formation,Moxi-Gaoshiti area,central Sichuan Basin,urges geologists to fix on deep,ancient,and organic-rich shale domain.To figure out both geochemical characteristics and sedimentary environment in source rocks of the Upper Sinian Doushantuo Formation will be momentous for deep to ultra-deep oil and gas exploration in the whole basin.Therefore,taken typical outcrop individually from Qingping town of Mianzhu city,Yangpingguan town of Ningqiang county,Xiaoyangba village of Zhenba county,and Gaoyan town of Chengkou county in northern basin as examples,such rocks were discussed from aspects of geochemical characteristics and redox conditions during source generation,as well as the effect of both paleoproductivity and hydrothermal activity on organic-matter accumulation by means of kerogen's microscopic examination,trace-element analysis and elemental-ratio test.Additionally,an extension model was investigated for the source rocks of Doushantuo Formation.Results show that(i)these source rocks whose extension is conditioned by sedimentary facies are featured by the thickness ranging from 8 m to 493 m,the total organic carbon(TOC)content from 0.71%to 2.60%,and the carbon-isotope value between-25.5‰ and-36.2‰ in kerogen presenting some characteristics of sapropelic-humic hybrid;(ii)apparently influenced by tectonic-sedimentary differentiation,the rocks exhibit strong heterogeneity and great difference in planar extension.Among which,waterbody deposited in basinal facies is formed in anoxic setting with notable hydrothermal impact and the average TOC of 2.6%,indicating these source rocks in high quality;and(iii)the accumulated organic matter in Doushantuo Formation of northern basin is mainly controlled by redox conditions,and partially contributed to hydrothermal activity,but the paleoproductivity effect is ill-defined.关键词
四川盆地北部/震旦系上统陡山沱组/烃源岩/地球化学特征/沉积环境/氧化还原条件/热液活动Key words
Northern Sichuan Basin/Upper Sinian Doushantuo Formation/Source rock/Geochemical characteristic/Sedimentary environment/Redox condition/Hydrothermal activity引用本文复制引用
邓剑,杜崇娇,张雷,刘栩,李龙龙..川北地区陡山沱组烃源岩地球化学特征与沉积环境[J].天然气勘探与开发,2025,48(3):1-13,13.基金项目
中国石化科技部项目(编号:P24235). （编号:P24235）
