海相油气地质2025，Vol.30Issue(1)：17-29,13.DOI:10.3969/j.issn.1672-9854.2025.01.002
塔河地区下寒武统玉尔吐斯组沉积环境及有机质富集机理
Sedimentary environment and organic matter enrichment mechanism of the Lower Cambrian Yuertusi Formation in Tahe area,Tarim Basin
摘要
Abstract
The Lower Cambrian Yuertusi Formation is an important source rock layer in Tarim Basin.The research on the organic matter enrichment mechanism could provide valuable guidance for the exploration of ultra-deep marine oil and gas reserves.Based on data of mineral petrology,inorganic geochemistry,and elemental analysis of Well A,combined with data of Well LT1 cited from reference,this study explores the sedimentary paleoenvironment of the Yuertusi Formation source rock in Tarim Basin and its control on organic matter enrichment,with integrated element geochemical indicators such as paleoproductivity,redox conditions and others.The results show that:(1)Yuertusi Formation in the Tahe area has high organic matter content,and the organic matter quality of the lower section,with an average TOC of 6%,is superior to the upper section.(2)Paleoproductivity level(P/Ti,Babio),water retention degree(Mo/TOC,Co·Mn),terrigenous detrital input(Ti/Al)and anoxia degree(Ni/Co,U/Th,V/Sc)show a gradual decreasing trend from early to late period of Yuertusi Formation.(3)Closely corresponded with variations in the sedimentary paleoenvironment induced by sea level fluctuations,the organic matter enrichment in the Yuertusi Formation is jointly influenced by preservation conditions,weak hydrothermal activity,and upwelling currents.In the early stage of Yuertusi,under a sea level of relatively low,a medium-high water retention developed,and the weak hydrothermal activity made the bottom seawater being in an anoxic state,and the long-term anoxic and sulfidation environment was conducive to the preservation of organic matter,thus the lower section of Yuertusi Formation with high TOC formed.In the late stage of Yuertusi,the sea level experienced fluctuating rise and gradual decline,the water retention degree reduced under the high sea level,and when the sea level decreased significantly,the environment gradually changed from anoxic to oxygen-poor,which may lead to the oxidation and decomposition of some organic matter,thus the upper section with low TOC formed.关键词
地球化学特征/古环境/有机质富集/玉尔吐斯组/寒武系/塔河地区/塔里木盆地Key words
geochemical characteristics/paleoenvironment/organic matter enrichment/Yuertusi Formation/Cambrian/Tahe area/Tarim Basin分类
石油、天然气工程引用本文复制引用
张文文,徐勤琪,尚凯,张楠,廖启丰,林静文,李帅..塔河地区下寒武统玉尔吐斯组沉积环境及有机质富集机理[J].海相油气地质,2025,30(1):17-29,13.基金项目
本文受中国石化科技项目"塔北-塔中震旦系—寒武系成藏条件与区带优选"(编号:P22123)资助 （编号:P22123）
