上扬子地台北缘下寒武统牛蹄塘组页岩稀土元素特征及其地质意义  

REE characteristics of shale in upper Cambrian Niutitang Formation at north margin of Upper Yangtze platform and the geological significance

作　　者：王宁 许锋 王喆 高骏 李华兵 WANG Ning;XU Feng;WANG Zhe;GAO Jun;LI Huabing(Shaanxi Mineral Resources and Geological Survey,Shaanxi Institute of Geological Survey,Xi’an 710068,Shaanxi,China)

机构地区：[1]陕西省地质调查院陕西省矿产地质调查中心,西安710068

出　　处：《地质找矿论丛》2024年第2期232-239,共8页Contributions to Geology and Mineral Resources Research

摘　　要：本文对上扬子地台北缘上寒武统牛蹄塘组页岩野外露头剖面采集的样品进行稀土元素测试分析,以探讨页岩的物质来源和沉积环境。研究结果表明:(1)牛蹄塘组页岩样品稀土总量较高,轻重稀土元素分异程度较高,呈现轻稀土元素富集、重稀土元素相对亏损的特征,配分曲线在轻稀土段右倾,重稀土段较为平坦,δEu和δCe分别呈现轻微的负异常和正常;(2)Ce_(anom)值总体反映沉积时的海水介质主要为缺氧的还原环境,有利于有机质的保存和富集,形成优质的烃源岩;(3)研究区东部、西部和中部沉积速率呈较快增加趋势,说明中部受汉南古隆起影响物源供给更加充沛;(4)物源构造背景为大陆岛弧切割的岩浆弧类型,研究区东、西部物源可能存在多源性,中部物源主要为沉积岩和大陆拉斑玄武岩。REE of samples collected from shale of Upper Cambrian Niutitang Formation at the northern margin of the Upper Yangtze platform along the field outcrop section are analyzed to discuss its material source and sedimentary environment.The total amount of rare earths of the sample is relatively high,and differentiation degree of LREE and HREE relatively high.LREE are enriched and HREE depleted.The REE pattern shows that LREE curves lean to right and those of HREE flat with slight negative δEu anomaly and slight positive δCe anomaly.The Ce_(anom) value generally reflects main anaerobic reducing environment of the seawater during deposition which is conducive to the preservation and enrichment of organic matter and favorable for formation of high-quality hydrocarbon source rocks.From east and west to central part of the study area deposition rate increases indicating that the central part is supplied with abundant material from Hannan paleo-uplift.The structure background of material source is a magma arc cut by continental island arc.Material source of the east and west parts may multiple.Sedimentary rocks and continental tholeiite are the main source of the central part.

关 键 词：稀土元素 牛蹄塘组 页岩 沉积物源 上扬子地区 

分 类 号：P595[天文地球—地球化学]