鄂尔多斯盆地砂岩型铀矿深穿透地球化学勘查方法实验  

Pilot study of deep-penetrating geochemical exploration for sandstone-type uranium deposit,Ordos Basin

作　　者：姚文生[1] 王学求[1] 张必敏[1] 徐善法[1] 申伍军[1] 杜雪苗[1] 

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000

出　　处：《地学前缘》2012年第3期167-176,共10页Earth Science Frontiers

基　　金：国土资源部行业专项"深部探测技术与实验研究"第四项目第三课题"盆地深穿透地球化学探测技术"(SinoProbe-04-03)

摘　　要：鄂尔多斯盆地尚未开展区域化探扫面工作。文中以东胜砂岩型铀矿区为例,开展深穿透地球化学勘查方法实验。东胜铀矿床产于侏罗系直罗组下段,为隐伏矿床。研究发现,富含细粒级地表结层是半干旱盆地砂岩型铀矿区域地球化学勘查的有效采样介质。在东胜砂岩型铀矿区及周边2 000km2的方法实验中,每4km2采集一个样品,过筛后取-200目进行全量分析,在矿化出露区及隐伏矿区圈出了铀及相关元素的地球化学异常。对元素比值R=lnU/(lnCe+lnY+lnZr+lnNb)在不同区域分布特征的研究表明,样品中活动态铀是形成铀异常的主要原因,提取细粒级土壤组分进行全量分析,可作为区域深穿透地球化学的砂岩型铀矿找矿指标。在矿床尺度深化穿透地球化学勘查方法中,因实验区地形特点使得富含细粒级地表结层样品不易普遍取得,地表土壤的全量分析不能满足勘查要求,需要采用铀专属性强的提取试剂进行元素活动态分析。文中采用作者研制的MML-U活动态提取剂,在东胜铀矿区孙家梁矿段剖面实验中,成功探测到矿体上方土壤中的U、Mo、V等元素的活动态异常。Ordos Basin contains concealed sandstone type uranium deposits in the lower Jurassic Zhiluo Formation.The study of the deep-penetrating geochemical methods will contribute to uranium exploration in the basin.The study shows that the collection and analysis of the clay-rich micro-surface soil provides a special application to regional geochemical exploration of sandstone type uranium deposit in the semi-arid terrains.Pilot geochemical mapping project covering 2000 km2 around Dongsheng uranium deposit area with the sampling density of 1 sample per 4 km2,successfully delineated the clear geochemical anomalies at the redox frontier zone and the concealed deposit belts.The study of the distribution patterns of R=lnCe＋lnY＋lnZr＋lnNb shows that the mobile forms of uranium should be the key factor causing the variation of the total content in surface soil samples.The soil sieving operation can be deemed to be the procedure of physical extraction of the deep-penetrating information for the concealed deposit.The content of uranium in the surface soil can be used as the key indexes for geochemical exploration of sandstone type uranium deposits in the basin.Due to the terrain features,the clay-rich micro-surface soil samples can be applied as the media for delineating the regional geochemical anomalies,but it cannot be always obtained in the exploration stage of locating the concealed orebodies.The application of the extractant of MML-U to selectively leaching the mobile forms of elements from soil along traverses over the Sunjialiang section of Dongsheng uranium deposit well delineated the U,Mo and V anomalies over the concealed orebodies.

关 键 词：鄂尔多斯盆地 砂岩型铀矿 细粒级样品 活动态提取剂 深穿透地球化学 

分 类 号：P619.14[天文地球—矿床学] P632[天文地球—地质学]