塔里木盆地古城地区蓬莱坝组白云岩稀土元素地球化学特征及其指示意义  

Rare earth element geochemistry of the dolomite in the Penglaiba Formation of the Gucheng area, Tarim basin and its implications

作　　者：郭春涛 陈继福[3] GUO Chuntao;CHEN Jifu(School of Mining and Civil Engineering, Liupanshui Normal University, Liupanshui 553004, China;Postdoctoral Research Station of Daqing Oilfield, CNPC, Daqing 163453, China;College of Architecture and Surveying Engineering, Shanxi Datong University,Datong 037003, China)

机构地区：[1]六盘水师范学院矿业与土木工程学院,六盘水553004 [2]中国石油天然气集团公司大庆油田博士后科研工作站,大庆163453 [3]山西大同大学建筑与测绘工程学院,大同037003

出　　处：《海洋地质与第四纪地质》2019年第4期66-74,共9页Marine Geology & Quaternary Geology

基　　金：国家自然科学基金青年项目“库车坳陷冲断构造带下侏罗统阿合组砂岩沉积—成岩结构与储层形成机制”(41802171)

摘　　要：塔里木盆地塔东低隆起中下奥陶统白云岩成因众说纷纭,严重阻碍了该区油气勘探步伐。基于岩芯、薄片、阴极发光等观察,针对塔东低隆起古城构造带中下奥陶统蓬莱坝组,对各种粒度白云岩、缝洞方解石、泥晶灰岩进行了系统的稀土元素地球化学特征的测试。各种粒度白云岩、缝洞方解石测试结果用泥晶灰岩稀土元素含量进行标准化。结果表明,样品稀土元素配分曲线可分为三种类型。综合白云岩岩石学特征和地球化学特征发现,较细粒白云岩及缝洞充填物呈现明显的负δCe特征,表明其形成于蒸发环境;较粗粒白云岩和缝洞充填物则分为负δEu型、正δEu型两种,其中负δEu型样品形成于埋藏环境,而正δEu型样品形成于热液环境。而早期形成的白云岩在埋藏过程中可能受到埋藏流体、热液流体的再作用。Disputes have occurred for a long time on the forming mechanism of the dolomite in the Lower Ordovician Penglaiba Formation in the Gucheng area of Tadong low uplift, Tarim Basin, that have seriously hindered oil and gas exploration there. This time, based on the observation of cores, thin sections and cathodoluminescence results, the geochemical characteristics of rare earth elements from various forms of dolomite, such as sparite, cave filling and micrite, are systematically analyzed. All the testing results are standardized by the rare earth elements in micrite. There observed three types of REE distribution patterns which suggest three kinds. The first kind of dolomitization is the buried dolomitization by fluids;the second kind of dolomitization formed in a hydrothermal environment, and the third kind driven by evaporative pump. Some dolomite formed earlier may be further modified and/or reformed by other kinds of dolomitization fluids later on.

关 键 词：白云岩 稀土元地球化学特征 塔里木盆地 蓬莱坝组 

分 类 号：TE122[石油与天然气工程—油气勘探]