岑巩页岩气区块牛蹄塘组黑色页岩稀土元素地球化学特征及沉积环境分析  

GEOCHEMICAL CHARACTERISTICS OF RARE EARTH ELEMENTS AND DEPOSITIONAL ENVIRONMENTS OF THE NIUTITANG FORMATION BLACK SHALE IN CEN′GONG SHALE GAS BLOCK

作　　者：毛瑞勇[1,2] 张杰[1,2] 冷济高 李鹏 王沙[1,2] MAO Rui-yong ZHANG Jie LENG Ji-gao LI Peng WANG Sha(Mining College of Guizhou University ,Guiyang 550025,China Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources,Guiyang 550025,China Tongren Sino-Energy Natural Gas Corporation , Tongren 554300,China)

机构地区：[1]贵州大学矿业学院,贵州贵阳550025 [2]贵州省非金属矿产资源综合利用重点实验室,贵州贵阳550025 [3]铜仁中能天然气有限公司,贵州铜仁554300

出　　处：《矿物岩石》2016年第4期66-73,共8页Mineralogy and Petrology

基　　金：贵州省科技厅重大应用基础研究项目(黔科合JZ字[2014]2005)

摘　　要：岑巩页岩气区块发育牛蹄塘组黑色页岩是一套优质烃源岩,是我国页岩气勘探开发亟待突破的重点层系之一。对该套黑色页岩采用电感耦合等离子体质谱仪(ICPMS)进行稀土元素(REE)测试分析,以揭示黑色页岩沉积环境。结果表明:总体上稀土元素总量较低(ΣREE为72.64×10^(-6)~156.98×10^(-6)),LREE相对富集(LREE/HREE为5.22~11.8),铕负异常较显著(δEu为0.40~0.58),铈呈弱负异常(δCe为0.74~0.98)。研究区黑色页岩母岩为先期沉积岩,形成于被动大陆边缘的相对较深的浅海斜坡环境;在早寒武世曾发生过一次明显的海侵-海退过程;沉积时水体为弱还原缺氧环境,沉积过程中有一个短暂的充氧期;沉积过程受到较强的热水作用的影响,上部和下部沉积速率低于中部;黑色页岩有机碳含量(TOC)与ΣREE存在较为明显的负相关性。对岑巩页岩气区块牛蹄塘组黑色页岩稀土元素地球化学分析,可为该区块进一步开展页岩气勘探开发工作提供参考。Niutitang Formation black shale in Cenrgong shale gas block is one significant stratum for Chinars shale gas and is a set of high quality source rocks. The rare earth elements of the black shale are analyzed by ICP-MS in order to reveal its depositional environment. It shows that the Niutitang Formation black shale is characterized by low rare earth elements content （∑REE ranges from 72. 64×10^-6 to 156. 98 ×10^-6）, relative enriched LREE （the LREE/HREE value from 5.22 to 11.8） ,obviously negative Eu abnormity （the δEu value from 0. 40 to 0. 58） ,and weakly negative Ce abnormity （the δCe value from 0. 74 to 0. 98）. The black shale develops in the relatively deep shallow-sea slope zone at passive continental margin,and their mother rocks are early sedimentary rock. The black shale is deposited in weak reduction hypoxie environment,and there is a short period of oxygenation in the deposition Process. Deposition is affected strongly by hot seawater and experienced a process of transgression-regression in the early Cambrian. The deposition rates of the upper and lower parts of the stratum are lower than those of the middle part. TOC and ∑REE of the black shale have obvious negative correlation, This study is helpful for the further exploration and development of Cen＇gong shale gas block.

关 键 词：牛蹄塘组 黑色页岩 稀土元素 地球化学 沉积环境 

分 类 号：TE121[石油与天然气工程—油气勘探] P595[天文地球—地球化学]