柴达木盆地北缘马海地区砂岩型铀成矿条件及找矿方向  

Metallogenic Conditions and Prospecting Targeting of Sandstone-type Uranium Mineralization in Mahai Area,Northern Qaidam Basin

作　　者：赵兴齐[1] 崔守凯 蔡亚[2] 卢冲 杨鲜鲜 张勇[2] 王伟 史清平[1] ZHAO Xing-qi;CUI Shou-kai;CAI Ya;LU Chong;YANG Xian-xian;ZHANG Yong;WANG Wei;SHI Qing-ping(CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing Research Institute of Uranium Geology,Beijing 100029;PetroChina Qinghai Oilfield Company,Dunhuang,Gansu 736202)

机构地区：[1]核工业北京地质研究院,中核集团铀资源勘查与评价技术重点实验室,北京100029 [2]中国石油青海油田公司,甘肃敦煌736202

出　　处：《地球学报》2021年第5期593-604,共12页Acta Geoscientica Sinica

基　　金：中国铀业有限公司科研项目“柴达木盆地砂岩型铀矿成矿环境分析及远景预测”(编号:201829-2);“柴达木盆地西部砂岩型铀矿成矿环境及远景评价研究”(编号:202118-3);国家重点基础研究发展计划(973计划)(编号:2015CB453004)联合资助。

摘　　要：通过对柴达木盆地北缘马海地区铀源条件、构造-建造特征、水文地质特征、后生蚀变特征及铀矿化特征进行系统分析,认为该区渐新统上干柴沟组及中新统下油砂山组具有较好的砂岩型铀矿找矿前景,是该区主要找矿目标层位。区内赛什腾山及绿草山铀源条件丰富,发育两翼产状较为平缓的背斜构造及沟通深部烃源岩及浅部砂体的深大断裂;辫状河、三角洲沉积体系发育,发育多套稳定的泥-砂-泥结构,地下水补-径-排体系完善。发育潜水氧化带型、潜水-层间氧化带型及层间氧化带型铀矿化,具水化异常、土壤氡气高异常及“两高夹一低”的铀矿找矿标志;铀成矿主要经历了沉积成岩预富集阶段、古潜水-古层间氧化成矿阶段、改造保矿三个阶段。马海背斜两翼斜坡构造带及马仙断裂附近的渐新统上干柴沟组和中新统下油砂山组辫状河河道亚相及三角洲平原分流河道亚相发育部位是马海地区砂岩型铀矿找矿的重点方向,找矿类型应以层间氧化带型和潜水-层间氧化带型为主,次为潜水氧化带型。Based on the systematic analysis of uranium source conditions,tectonic features,hydrogeological features,epigenetic alteration features and uranium mineralization features in Mahai area of Northern Qaidam Basin,the authors infer that the Upper Ganchaigou Formation of Oligocene period and the Lower Youshashan Formation of Miocene period have a good prospect for exploration of sandstone-type uranium deposits in this area.With two relatively gentle anticlines and deep faults connecting deep source rocks and shallow sand bodies and well-developed sedimentary systems of braided river and delta,Saishitengshan and Lücaoshan area has abundant uranium sources.A number of stable mudstone-sandstone-mudstone structures have been developed,with a perfect complement-runoff-drainage system of groundwater.Furthermore,phreatic oxidation zone,phreatic-interlayer oxidation zone and interlayer oxidation zone uranium mineralizations are developed,which are characterized by uranium prospecting indicators with hydration anomaly,high soil radon anomaly and“two high and one low”feature.The uranium mineralization process mainly experienced three stages:sedimentary-diagenetic pre-enrichment stage,paleo-phreatic water and paleo-interlayer oxidation stage,and transformation and preservation stage.It can be suggested that,near Maxian fault and slope structural belt of Mahai anticline,the braided channel subfacies and delta plain distributary channel subfacies of Upper Ganchaigou Formation of Oligocene period and Lower Youshashan Formation of Miocene period constitute the key prospecting directions of sandstone-type uranium deposits in Mahai area,and the main prospecting types are interlayer oxidation zone and phreatic-interlayer oxidation zone,followed by phreatic oxidation zone.

关 键 词：砂岩型铀矿 成矿条件 找矿方向 古近系—新近系 马海地区 柴达木盆地 

分 类 号：P612[天文地球—矿床学]