石油实验地质2025，Vol.47Issue(6)：1329-1342,14.DOI:10.11781/sysydz2025061329
川南威远地区西缘下志留统龙马溪组黑色页岩沉积古环境及其对有机质富集的控制
Sedimentary paleoenvironment and its control on organic matter enrichment of black shale in Lower Silurian Longmaxi Formation on western margin of Weiyuan area,southern Sichuan Basin
摘要
Abstract
Current research on sedimentary paleoenvironments and the main factors controlling organic matter enrichment in the southern Sichuan Basin primarily focuses on the Luzhou subsag area,while studies on the Weiyuan area near the Leshan-Longnüsi paleo-uplift are relatively scarce.This has led to an unclear understanding of the main controlling factors of organic matter enrichment in the area.Accordingly,through a comparative analysis of the sedimentological and organic geochemical characteristics of the Lower Silurian Longmaxi Formation on the western margin of the Weiyuan area,the main controlling factors and formation models of organic matter enrich-ment were explored.The results indicated that during the LM1-LM5 sedimentary periods(Rhuddanian),the basin experienced flexural subsidence.Tectonic activity was stable,sea level was at its highest,terrigenous clastic input was low,and the water body was predominantly anoxic.Preservation conditions,terrigenous clastic input,and paleoproductivity collectively resulted in the highest organic matter content in this sedimentary period.In the LM6 sedimentary period(early Aeronian),the basin entered a flexural-migration phase.Tectonic activity intensi-fied,the barrier in the passive continental margin area of northern Chongqing began to open,ocean current activity strengthened,and the bottom-water environment was mainly anoxic to dysoxic.The deterioration of preservation conditions and the increased paleoproductivity were the main factors leading to only minor difference in total organic carbon(TOC)content compared with the LM1-LM5 sedimentary periods.During the LM7 sedimentary period(middle Aeronian),the barrier continued to open,sea level dropped further,bottom-water reducibility became worsened,and ocean current activity continued to intensity.The deterioration of preservation conditions and increased terrigenous clastic input were the main factors causing the decrease in organic matter content.During the LM8 sedimentary period(late Aeronian),ocean current activity reached its peak and paleoproductivity rose to its highest level.However,the bottom-water environment became dysoxic to oxic.The deterioration of preser-vation conditions was the main factor causing the organic matter content to drop to its lowest level.It is concluded that the continuous decrease in organic matter content within the study area is closely related to the sedimentary paleoenvironment evolution process,which was primarily controlled by paleogeomorphology and sea-level fluctuations.关键词
上升洋流/前陆挠曲演化/有机质富集/乐山—龙女寺古隆起/威远地区/四川盆地Key words
rising ocean current/foreland flexure evolution/organic matter enrichment/Leshan-Longnüsi paleo-uplift/Weiyuan area,Sichuan Basin分类
能源科技引用本文复制引用
李生美,沈均均,叶成林,白森,熊小林,谢锐杰,程辉,陈浩,孟江辉..川南威远地区西缘下志留统龙马溪组黑色页岩沉积古环境及其对有机质富集的控制[J].石油实验地质,2025,47(6):1329-1342,14.基金项目
国家自然科学基金面上项目"四川盆地下志留统埃隆阶页岩中钡的差异富集及其对有机质富集的启示"(42372168)资助. （42372168）
