巫溪地区五峰组——龙马溪组页岩有机质沉积模式

发布时间：2018-01-05 19:17

本文关键词：巫溪地区五峰组——龙马溪组页岩有机质沉积模式　出处：《中国矿业大学学报》2017年05期 　论文类型：期刊论文

【摘要】：对巫溪地区田坝剖面五峰组—龙马溪组底部30件页岩样品开展了有机碳含量、微量元素地球化学等方面研究,分析了不同层段有机质富集特征及其控制因素,认为海平面升降控制着水体缺氧程度,从而影响该区有机质沉积富集程度.研究结果表明:1)五峰组—龙马溪组底部页岩中共识别出4个有机质沉积阶段,总有机碳(TOC)含量整体较高,TOC平均达到3.7%,但与古生产力(生源钡Babio含量)相关性不明显,指示着古生产力总体上不是该时期有机质沉积的主控因素;2)尽管不同有机质沉积阶段的水体氧化还原条件具有一定差异性,但与TOC变化总体上具有相关性,这表明这些时期有机质沉积主要受控于缺氧程度,其富集机理属于"保存模式";3)五峰组—龙马溪组早期有机质沉积模式为:海平面的升降控制着沉积水体的缺氧程度,海平面下降造成底水富氧,上升形成底水缺氧,从而控制着页岩中有机质富集程度.
[Abstract]:The organic carbon content and trace element geochemistry of 30 shale samples from Wufeng formation to Longmaxi formation in Tianba section of Wuxi area were studied. The enrichment characteristics and controlling factors of organic matter in different layers were analyzed. It is considered that sea level rise and fall control the degree of hypoxia in the water body, thus affecting the enrichment of organic matter in this area. The results show that the bottom shale of Wufeng formation and Longmaxi formation identifies four stages of organic matter deposition in the bottom of the Wufeng formation and Longmaxi formation. The total organic carbon (TOC) content of TOC was 3. 7%, but it was not correlated with paleoproductivity (biotic barium Babio content). It indicates that paleoproductivity is not the main controlling factor of organic matter deposition in this period. 2) although the conditions of water redox were different in different organic deposition stages, there was a general correlation with the changes of TOC, which indicated that the organic matter deposition in these periods was mainly controlled by the degree of hypoxia. The enrichment mechanism belongs to "preservation mode"; 3) the early organic matter deposition model of Wufeng formation and Longmaxi formation is as follows: the rise and fall of sea level control the degree of anoxia in sedimentary water, and the drop of sea level results in oxygen-rich in bottom water, and the rising results in anoxia in bottom water. Thus controlling the enrichment degree of organic matter in shale.
【作者单位】：国家能源页岩气研发(实验)中心;中国石油勘探开发研究院;东华理工大学地球科学学院;
【基金】：国家自然基金项目(41602119) 中国石油科学研究与技术开发项目(2016B-0302-01) 中石油勘探开发研究院项目(XN41601,XN41603)
【分类号】：P618.13
【正文快照】： 2.中国石油勘探开发研究院,北京100083;3.东华理工大学地球科学学院,江西南昌330013)页岩气作为非常规油气资源重要类型之一,资源潜力巨大[1-3],近10a以来已成为国内外地质勘探家们研究的热点领域[4-10].四川盆地及其周缘五峰组—龙马溪组富有机质海相页岩具有含气厚度大、成

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