鄂尔多斯盆地东北部塔然高勒地区侏罗系直罗组含铀地层地球化学特征分析  

Elemental Geochemical Characteristics of Jurassic Uranium-bearing Zhiluo Formation in Taran Gol Area,Northeastern Ordos Basin

作　　者：王善博 张超[1] 张天福 朱强 俞礽安 司庆红 WANG Shan-bo;ZHANG Chao;ZHANG Tian-fu;ZHU Qiang;YU Reng-an;SI Qing-hong(China Geological Survey,Tianjin Geological Survey Center,Tianjin 300170,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170

出　　处：《科学技术与工程》2021年第1期77-86,共10页Science Technology and Engineering

基　　金：国家重点基础研究发展计划(973计划)(2015CB453000);中国地质调查局地质调查项目(DD20160127)。

摘　　要：沉积岩的地球化学特征记录了岩石沉积时的重要地质信息,是研究沉积古环境、源区构造背景及源岩属性的有效手段。采用X衍射荧光光谱(XRF)、等离子体质谱仪(ICP-MS)和CMS350A型岩心扫描仪对鄂尔多斯盆地东北部塔然高勒地区中侏罗统直罗组地层岩心样品的主量元素、微量元素、稀土元素及黏土矿物含量进行测试分析,综合研究塔然高勒地区直罗组地层的沉积古气候特征、古水体氧化还原条件、古水体盐度及物源特征。研究表明:Sr/Cu、Rb/Sr、FeO/MnO、Mg/Ca及Al2O3/MgO、化学蚀变指数(CIA)以及黏土矿物组合特征等指标综合指示出,研究区中侏罗世直罗早期为干旱气候,到直罗中期气候逐渐湿润,而后到直罗晚期气候再次变得干旱。古水体环境整体为富氧的淡水-半咸水环境。结合常量、微量、稀土元素各种构造背景判别方法,认为研究区直罗组地层源区构造背景主要是与大陆岛弧相关的活动大陆边缘,源岩可能为盆地北部阴山造山带内古生代中酸性侵入岩和大青山-乌拉山-集宁地区前寒武纪变质岩。The geochemical characteristics of sedimentary rocks which recording important geological information during the process of rock deposition had been proven as an effective means to study thepaleoenvironment,the tectonic setting and the attributes of provenance.An comprehensive study of the paleoenvironment,the tectonic setting and provenance attribute of lower of Zhiluo Formation was carried out by testing and analyzing the content of major elements,trace elements,rare earth elements and clay minerals of the sandstone and mudstone samples collected from Middle Jurassic Zhiluo Formation at Taran Gol area in the northeast margin of the Ordos Basin using the method of X-ray fluorescence(XRF),inductively coupled plasma mass spectrometry(ICP-MS)and CMS350A core scanner.The research indicates that Sr/Cu ratio,Rb/Sr ratio,FeO/MnO ratio,Mg/Ca ratio,Al2O3/MgO ratio,chemical index of alteration(CIA)and clay mineral combination characteristics as well as other geochemical indexes suggest that drought-wetdrought paleoclimate of Zhiluo Formation,and the oxygen enrichment-secondary oxygen enrichment freshwater-brackish environments as the paleo-water conditions of it.The rare earth feature proves that the provenances of lower of Zhiluo Formation may derived mainly from the Paleozoic acid intrusive rock in Yinshan Orogenic Belt in Northern Ordos Basin and the Precambrian metamorphic rocks in Daqingshan-Wulashan-Jining area.The tectonic setting of provenance area is mainly related to the Continental edge and the Continental island arc.

关 键 词：元素地球化学 物源分析 古沉积环境 直罗组 砂岩型铀矿 鄂尔多斯盆地东北部 

分 类 号：P588.22[天文地球—岩石学]