成都理工大学学报（自然科学版）2025，Vol.52Issue(4)：643-657,15.DOI:10.12474/cdlgzrkx.2024111102
四川盆地北部茅口组孤峰段拉张海槽演化过程与沉积条件
Sedimentary conditions of the Gufeng member of the Maokou Formation in northeastern Sichuan Basin and their implications for the formation of the extension trough
摘要
Abstract
Significant tectonic activity during the late stage of the Maokou Formation in Sichuan Basin resulted in an NW-SE trending trough in the NE Sichuan Basin.The beaches in the western margin of the trough have become a realistic field for conventional natural gas exploration,while the organic-rich mudstone and marl in the trough are potential fields for unconventional natural gas exploration.However,to date no detailed study on the formation conditions of the black siliceous limestone and argillaceous limestone in the Gufeng member,including the sedimentary process,has been performed.To address this,we carry out a detailed petrological and geochemical study of the black siliceous mudstone and argillaceous limestone of the Gufeng member for three field outcrop sections in the trough:The Xibeixiang,Qiaoting,and Xuebaoshan sections.The results from our sedimentary analysis suggest that the Gufeng member can be subdivided into two transgressive-regressive cycles;i.e.,upper and lower ones.In the lower part of the Gufeng member,there are two extensions in the southeastern and the northwestern parts of Sichuan Basin.The Gufeng member was generally sub-reduced to a reduced hypoxia state.From the lower part to the upper part,the degree of reduced hypoxia state strengthened,from suboxic-reduction conditions to reduction-sulfurization conditions,and the water in the Xuebaoshan section,located in the southeastern trough,was more reduced than that in the northwestern trough.The Gufeng member formed during generally perennial upwelling conditions within an overall reducing environment.During the sedimentary process of the lower part of the Gufeng member,the water body in the northwest section was more accessible to the open sea than in the southeastern trough.The water body was restricted and stagnant in the Qiaoting section in the upper part of the Gufeng member,due to a drop in sea level during this period,making it overall less accessible to the open sea.关键词
茅口组/孤峰段/氧化还原/沉积条件/四川盆地Key words
Maokou Formation/Gufeng member/redox/sedimentary conditions/Sichuan Basin分类
天文与地球科学引用本文复制引用
XIE Jingping,LI Yaxi,ZHANG Xihua,PENG Hanlin,GAO Zhaolong,LI Tianjun,ZHU Jianchao,HU Guang..四川盆地北部茅口组孤峰段拉张海槽演化过程与沉积条件[J].成都理工大学学报（自然科学版）,2025,52(4):643-657,15.基金项目
国家社会科学基金重大项目(24&ZD164). （24&ZD164）
