湘中南地区中奥陶统烟溪组黑色页岩地球化学特征与有机质富集  

Geochemical Characteristics and Organic Matter Enrichment of Black Shale in the Middle Ordovician Yanxi Formation in Central and Southern Hunan

作　　者：蔡灵慧 余烨[1,2] 郭建华[3] 黄俨然[1,2] 郭原草 Cai Linghui;Yu Ye;Guo Jianhua;Huang Yanran;Guo Yuancao(Hunan Provincial Key Laboratory of Shale Gas Resource Utilization,Hunan University of Science and Technology,Xiangtan 411201,Hunan,China;School of Earth Science and Spatial Information Engineering,Hunan University of Science and Technology,Xiangtan 411201,Hunan,China;School of Geosciences and Info-Physics,Central South University,Changsha410083,China)

机构地区：[1]湖南科技大学页岩气资源利用湖南省重点实验室,湖南湘潭411201 [2]湖南科技大学地球科学与空间信息工程学院,湖南湘潭411201 [3]中南大学地球科学与信息物理学院,长沙410083

出　　处：《吉林大学学报（地球科学版）》2023年第5期1362-1379,共18页Journal of Jilin University：Earth Science Edition

基　　金：湖南省自然科学基金项目(2019JJ50151);湖南省教育厅科研项目(18C0374)。

摘　　要：为了研究湘中南地区中奥陶统烟溪组富含有机质的黑色细粒岩系的地球化学特征与富集模式,选取了宁远棉花坪(MHP)、双牌何家洞(HJD)、全州沙子塘(SZT)等剖面,测试样品的有机质丰度并对其主量、微量和稀土元素进行地球化学元素分析。结果表明:湘中南地区中奥陶统烟溪组有机地球化学指标较好,SiO_(2)质量分数高,属于优质烃源岩;黑色页岩有机质丰度比较高,w(TOC)平均值为2.12%,普遍高于2%,脆性矿物体积分数在50%以上,具有很好的生气能力。烟溪组内发育的大量硅质层主要为沉积成因,氧化还原参数U/Th,V/(V+Ni)等指标指示水体整体为贫氧的还原环境,烟溪组时期生产力较高;陆源物质输入、氧化还原环境、海平面相对变化和古生产力等方面因素共同影响着有机质的富集,烟溪组页岩有机质的富集主要受控于缺氧环境,属于“深水滞留盆地”的富集模式。In order to study the geochemical characteristics and enrichment patterns of the organic-rich black fine-grained rock series in the Middle Ordovician Yanxi Formation in the central and southern Hunan,samples from Ningyuan Mianhuaping(MHP),Shuangpai Hejiadong(HJD),Quanzhou Shazitang(SZT)and other sections are collected and analyzed for TOC,major elements,trace elements and rare earth elements.The results show that the organic geochemical index of the Middle Ordovician Yanxi Formation in the central and southern Hunan is good,and the SiO_(2) content is high,which belongs to the high-quality source rock;The organic matter abundance of the black shale is relatively high,the average w(TOC)is 2.12%,which is generally higher than 2%,and the brittle mineral content is more than 50%,so it has good gas generating capacity.The large number of siliceous layers developed in the Yanxi Formation are mainly of sedimentary origin.The redox parameter U/Th,V/(V+Ni)and other indicators indicate that the overall water body is an oxygen-limited reductive environment,and the productivity of the Yanxi Formation was high;The terrigenous material input,redox environment,relative changes of sea level,and paleoproductivity affect the enrichment of organic matter together.The enrichment of organic matter in the shale of Yanxi Formation is mainly controlled by the anoxic environment,which belongs to the enrichment model of“deep-water retention basins”.

关 键 词：湘中南地区 烟溪组 黑色页岩 地球化学 有机质 

分 类 号：TE122[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]