地质学报2024，Vol.98Issue(1)：266-279,14.DOI:10.19762/j.cnki.dizhixuebao.2023038
珠江口盆地珠三坳陷文昌组有机质碳同位素异常成因
Origin of the abnormal carbon isotopic in organic matter of the Wenchang Formation,Zhu Ⅲ sub-basin,Pearl River Mouth basin
摘要
Abstract
The phenomenon of sapropelic organic matter with high carbon isotope values,coupled with an abnormally high abundance of total organic carbon and hydrocarbon potential,has been identified in certain offshore lacustrine basins in China and rifting basins in the Atlantic.In this paper,we aim to investigate the mechanism behind the positive deviation of carbon isotope values within the organic matter of the Paleogene Wenchang Formation.Our research approach involves analyzing the organic carbon content,pollen,major and trace elements,as well as the carbon isotope and gas chromatograph-mass spectroscopy(GC-MS)of saturated hydrocarbon in both source rocks and crude oils.We also consider the characteristics of pediastrum in modern lakes to gain insights into the sources of organic matter,ancient environmental conditions,and the preservation and transformation of organic matter.The carbon isotope anomaly observed in the Wenchang Formation appears to be closely linked to various ancient environmental factors,including paleoclimate,paleoproductivity,and flourishing algae in the Zhu Ⅲ sub-basin.However,paleobathymetry may be a non-negligible significant factor on the scale of the third-order sequence.The Rb/K ratio,indicating the water depth,exhibits an increasing trend with depth,which coincides with the variations observed in carbon isotope values and TOC content.Additionally,modern lake investigations confirm the distribution of pediastrum across different water depths.Therefore,the bloom of"deep water type of pediastrum"is considered a key factor contributing to the high carbon isotope values observed in source rocks within the 2nd Member of the Wenchang Formation in the Zhu m sub-basin.关键词
腐泥型有机质/碳同位素/古环境/盘星藻/珠三坳陷/珠江口盆地Key words
sapropelic organic matter/carbon isotope/paleoenvironment/pediastrum/Zhu Ⅲ sub-basin/Pear River Mouth basin引用本文复制引用
何智同,尹相东,陈世加,雷明珠,朱必清,刘杨,赵荣茜,刘宇阳..珠江口盆地珠三坳陷文昌组有机质碳同位素异常成因[J].地质学报,2024,98(1):266-279,14.基金项目
本文为国家自然科学基金项目(编号42002176,41872165,42072185)资助的成果. （编号42002176,41872165,42072185）
