Sedimentary Environment and Organic Matter Enrichment Mechanism of the Lower Member of the Xingouzui Formation in the Jianghan Basin during the Early Eocene
Fan Xiaojie
Teng Xiaohua
Wang Chunlian
Zhang Jingyu
Lu Yangbo
Zhang Liang
Lu Yongchao
Li Long
Qin Zhanjie
Abstract：The potential of continental shale oil resources in China is enormous,and the lower member of the Xingouzui Formation(LXF)from the Early Eocene serves as the primary target for shale oil exploration in the Jianghan basin.Previous research has mainly focused on hydrocarbon generation potential and reservoir characteristics,while discussions regarding its depositional environment evolution and mechanisms of organic matter enrichment remain relatively scarce.This study takes the Early Eocene LXF from the SKD1 and CY1 boreholes as the main research object.Based on lithofacies,elemental,and isotopic geochemical analyses,it investigates the paleoenvironmental changes and organic matter enrichment mechanisms of the LXF.The results indicate that organic matter content in the LXF is relatively low,with an average total organic carbon(TOC)of 0.9%.During the Paleocene-Eocene Thermal Maximum(PETM),rapid warming and oxidative conditions accelerated the decomposition of organic matter,resulting in relatively low organic matter content,with a TOC of only 0.5%.In contrast,during arid climatic periods,increasing lake salinity led to the sequential deposition of evaporative minerals such as anhydrite and glauberite.Under high-salinity conditions,halophilic organisms contribute to part of the productivity.High salt and hypoxic environment promotes the production and preservation of organic matter,with average TOC increaing to 2.56%.These findings indicate that organic matter enrichment in the Jianghan basin during the Eocene was primarily controlled by synergy of productivity and preservation conditions.This study provides insights into the mechanisms of organic matter preservation in continental saline lacustrine basins under greenhouse climate conditions and provides a theoretical basis for identifying favorable stratigraphic intervals for future oil and gas exploration.
Keywords：Jianghan basinEarly Eoceneorganic matter enrichmentpaleoenvironmentelemental compositionsedimentologypetroleum geology
Publication Date：2025-05-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 1953-1967 )