Abstract
In the Tarim Basin, the largest petroliferous basin in China, a set of organic-rich deposition hosted in the lower Cambrian Yuertusi Formation is considered to be the main hydrocarbon source rocks. However, the limited and scattered distribution of the lower Cambrian constrains present studies mostly on some certain sections where samples are accessible, inhibiting a systematic understanding of characteristics of these source rocks and controls on organic matter enrichment. Here, we conduct a systematic study on a drillcore in northwestern margin of the Tarim Basin (Taxibei), integrated with previously published data from other available sections. These data show the Yuertusi Formation was mainly composed of mudstone/shale, carbonate and siliceous rocks, and distributed dominantly in the Taxibei, northern (Tabei) and eastern-northeastern areas of the Tarim Basin (Tadong-Tadongbei) with an increased thickness (mean 30 m to mean 60 m) towards the Tadong-Tadongbei areas. High total organic carbon (TOC) contents (up to 30%) were found in the mudstone/shale dominated intervals in both the Taxibei and Tabei areas, characterized by I-II kerogen and highly to over-matured thermal maturity. Paleo-redox reconstruction based on high V/(V + Ni) ratios (>0.6) and FeHR/FeT ratios (>0.38) suggests anoxic watermass conditions occurred during the deposition of the organic-rich intervals along with moderate sedimentation rate, providing consistently good preservation for organic matter accumulation. Based on a combined analysis, we infer primary productivity in surface waters exerted a key control on TOC contents of the organic-rich intervals, which was driven by nutrient supplies from hydrothermal activities with partial upwelling effects in the Taxibei area, and from upwelling waters in the Tabei area.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
