塔里木盆地北缘日达里克铀矿床后生蚀变特征及其铀矿成因意义

Alteration Characteristics and Its Genetic Significance of Ridalike Uranium Deposit in the Northern Tarim Basin

日达里克铀矿床为塔里木盆地北缘新近系铀矿找矿成果的典型代表,其成因研究可为相同地区、构造背景、层位的铀矿找矿工作提供借鉴。文章在介绍区域地质背景的基础上,对日达里克铀矿床及典型矿带进行详细解剖,对含矿主岩后生蚀变分带及其岩石地球化学特征进行研究,浅析后生蚀变成因,综合判断矿床成因类型。研究显示,日达里克铀矿床产出有多个矿带,各矿带赋矿砂体均可划分为发育高岭土化的灰白色岩石类型、发育褐铁矿化的褐黄色岩石类型及未见明显蚀变特征的灰色岩石类型。赋矿砂体岩性-地球化学分带自西向东可划分为氧化蚀变带、氧化还原过渡带及原生未蚀变带,其中氧化蚀变带包括灰白色岩石类型、褐黄色岩石类型,氧化还原过渡带包括褐黄色岩石类型、灰色岩石类型,原生未蚀变带包括灰色岩石类型。主要地球化学指标显示氧化还原过渡带高w(U)、w(Mo)、w(Se)、w(Ga)、w(V)、w(Re)、w(Fe)、w(C_(有))、w(S)及Fe^(3+)/Fe^(2+)值,氧化蚀变带相对高w(Mo)、w(Se)、w(Ga)、w(V)及Fe^(3+)/Fe^(2+)值,原生未蚀变带相对高w(U)、w(Re)、w(S)值,反映氧化蚀变带为后生氧化成因。研究表明,日达里克铀矿床岩性-地球化学分带与层间氧化型砂岩型铀矿一致,矿床成因应属层间氧化带型;下一步工作需在梳理以往地面调查、钻孔资料的基础上,沿走向追溯、垂直走向探索层间氧化还原过渡带。

Ridalik uranium deposit is a typical representative of uranium prospecting achievements in Neogene in the northern margin of Tarim Basin.Beginning with the regional geological background,this paper analyzed Ridalik uranium deposit and its typical ore belt in detail,studied the epigenetic alteration zoning of the host rock and its petrogeochemical characteristics,discussed the genesis of epigenetic alteration,and the genetic type of deposit.The research showed that there are several ore belts in Ridalik uranium deposit,and the ore hosting sand bodies in each ore belt can be divided into gray white rock types with kaolinization,brown yellow rock types with ferritization,and gray rock types without obvious alteration.The petrogeochemical zoning of ore hosting sand body can be divided into oxidation alteration zone,redox transition zone and original rock zone from the west to the east.The oxidation alteration zone includes gray white and brown yellow rock,the redox transition zone includes brown yellow and gray rock,and the original rock zone includes gray rock type.The main geochemical indicators showed that the redox transition zone is high in w(U),w(Mo),w(Se),w(Ga),w(V),w(Re),w(Fe),w(C_(has)),w(S),and Fe^(3+)/Fe^(2+);the oxidation alteration zone is relatively high in w(Mo),w(Se),w(Ga),w(V),and Fe^(3+)/Fe^(2+);the original rock zone in relatively high in w(U),w(Re),and w(S),reflecting that the oxidation alteration zone is of epigenetic oxidation origin.The study showed that the petrogeochemical zonation of Ridalik uranium deposit is consistent with the interlayer oxidation sandstone type uranium deposit,and the deposit genesis should belong to the interlayer oxidation zone type.The next exploration should trace along the strike and explore the interlayer redox transition vertical to the strike based on reviewing previous ground surveys and drilling data.