石油实验地质2025，Vol.47Issue(5)：1003-1016,14.DOI:10.11781/sysydz2025051003
塔里木盆地柯坪地区玉尔吐斯组同位素地层学研究
Isotope stratigraphy of Yurtus Formation in Keping area,Tarim Basin:chemical stratigraphic correlation and age constraints based on Carbon and Strontium isotopes
摘要
Abstract
The Late Neoproterozoic to Early Cambrian represents a critical period in geological history.In the Keping area of the Tarim Basin,Xinjiang,the Ediacaran to Cambrian strata are well-exposed,but research on chemostratigraphy is relatively limited.This study selected the Lower Cambrian Yurtus Formation in the Xiaoerbulake Xigou and Kungaikuotan sections in the Keping area as the research subject.Carbon and Strontium isotope geo-chemistry were used to establish regional and global stratigraphic correlations and constrain the depositional age of the Yurtus Formation.The geochemical characteristics of the samples,including δ13Ccarb-δ18Ocarb crossplots,δ18 Ocarb,and Mn/Sr ratios,confirmed that the δ13 Ccarb and87 Sr/86 Sr of most samples were not altered by later diagenesis and preserved the seawater characteristics at the time of deposition.Crossplots of 87 Sr/86 Sr versus Sr content and Rb content of the samples indicated that there was no significant addition of silicate components during the dissolution process.The inorganic carbon isotope results showed that two negative carbon isotope excursions were recorded in the carbonates from the Yurtus Formation in both sections,located at the base of limestone and shale interbeds and in the upper argillaceous limestone member,respectively,which could be correlated with other sections in the Keping area.The 87 Sr/86 Sr ratios of Yurtus Formation carbonates exhibited a"decline-rise"pattern,which could be correlated with the 87 Sr/86 Sr variations in the Tommotian Stage of Morocco and southeastern Siberia.The global positive carbon isotope excursion ZHUCE event was not identified within the Yurtus Formation.Combined with 87 Sr/86 Sr variation characteristics and paleontological data,it is inferred that there was a sedimentary hiatus within the formation,resulting in the absence of the middle and lower Stage 2 strata.Based on carbon and stronti-um isotope stratigraphic correlations combined with previous studies,it is concluded that the middle dolomite member of the Yurtus Formation lies near the Fortunian and Stage 2 boundary,and the upper limestone and shale interbeds to the top of the Yurtus Formation belong to the late Stage 2 and early Stage 3 of the Cambrian.关键词
碳同位素/锶同位素/地层对比/玉尔吐斯组/塔里木盆地Key words
carbon isotope/strontium isotope/stratigraphic correlation/Yurtus Formation/Tarim Basin分类
能源科技引用本文复制引用
吕心雄,杨涛,朱碧..塔里木盆地柯坪地区玉尔吐斯组同位素地层学研究[J].石油实验地质,2025,47(5):1003-1016,14.基金项目
国家自然科学基金重点项目(41830425)和中国科学院战略性先导科技专项B类子课题(XDB26000000)联合资助. （41830425）
