塔里木盆地柯坪地区奇格布拉克组古环境研究  

Study on the paleoenvironment of Qigbulak Formation in Keping area,Tarim Basin

作　　者：冯琳[1] 杨欢 李乐 彭丽[1] 杨果[1] 王晓雪 FENG Lin;YANG Huan;LI Le;PENG Li;YANG Guo;WANG Xiaoxue(Tarim Oilfield Company,PetroChina,Korla 841000,China;Hubei institute of Geosciences,Wuhan 430034,China)

机构地区：[1]中国石油塔里木油田公司,新疆库尔勒841000 [2]湖北省富硒产业研究院,湖北武汉430034

出　　处：《断块油气田》2024年第5期802-809,共8页Fault-Block Oil & Gas Field

摘　　要：埃迪卡拉纪—寒武纪地层因缺乏岩浆岩和可靠的年代学数据,导致地层划分与对比存在争议。文中以埃迪卡拉纪—寒武纪的奇格布拉克组地层为研究对象,利用塔西北什艾日克露头采样,精细分析岩石学特征,对碳酸盐岩的碳、氧同位素采样数据进行有效性评估,开展古海水盐度和古海水温度的研究,并讨论该组地层的碳同位素正异常的原因,为埃迪卡拉纪—寒武纪的奇格布拉克组地层划分和对比提供参考。结果表明:1)奇格布拉克组下部以混合沉积为主,表现为微生物白云岩、混积岩、碎屑岩的薄互层;中上部主要发育中—厚层状微生物碳酸盐岩;2)奇格布拉克组沉积期海水呈现出温度逐渐升高、盐度逐渐降低的规律,且盐度变化趋势相比温度更加显著;3)奇格布拉克组下部的碳同位素正异常与沉积环境密切相关。陆源输入促进初级生产力的提升,贫氧条件则进一步使有机碳埋藏量增大,海水中的δ^(13)C升高,形成奇格布拉克组下部的正异常。The division and correlation of Ediacaran-Cambrian stratum are controversial due to the lack of magmatic rocks and reliable chronological data.In this paper,the Qigbulak Formation of the Ediacaran-Cambrian is taken as the research object,detailed analysis of petrological features are conducted,and the validity of the carbon and oxygen isotope sampling data of carbonate rocks is evaluated by using the samples taken from the outcrop in Shiersk,northwest of Tarim Basin.The study of paleo-seawater salinity and temperature is carried out,and the causes of the carbon isotope positive anomalies in this formation are discussed,providing a reference for the stratigraphic division and correlation of Qigbulak Formation in the Ediacaran-Cambrian.The results show that:(1)The lower part of Qigbulak Formation was dominated by mixed sediments,which are thin interlayers of microbial dolomite,mixed rock and clastic rock.The middle and upper part mainly developed medium to thick bedded microbial carbonate rocks.(2)During the sedimentary period of Qigebulak Formation,the seawater temperature gradually increased and the salinity gradually decreased,and the salinity trend was more significant than that of temperature.(3)The carbon isotope positive anomaly in the lower part of Qigbulak Formation were closely related to the depositional environment.Terrigenous input promoted the increase of primary productivity,and the oxygen-poor condition of seawater further increased the amount of organic carbon buried and increased theδ^(13)C in seawater,forming a positive anomaly at the bottom of Qigbulak Formation.

关 键 词：碳同位素 氧同位素 古海洋环境 奇格布拉克组 塔里木盆地 

分 类 号：TE122[石油与天然气工程—油气勘探] P597[天文地球—地球化学] P532[天文地球—地质学]