沉积盆地源汇过程及其演化对砂岩型铀矿成矿的制约--以新疆伊犁盆地南缘蒙其古尔铀矿床为例

摘要

笔者以新疆伊犁盆地南缘蒙其古尔铀矿床为例，探讨了物源、铀源及两者的汇集过程对铀成矿的控制，揭示沉积盆地源汇过程及其演化对砂岩型铀矿成矿的制约。通过分析蒙其古尔铀矿区目的层岩石中的重矿物组合、稀土元素配分型式并与蚀源区典型岩石进行对比，查明目的层物源区岩石主要为以花岗岩为主的酸性火成岩，其中活性铀含量较高，为本区的铀源体。沿目的层沉积路径，铀矿体优先产于砂体厚度急剧减薄、泥质夹层增多和砂岩粒度由粗变细等岩性突变部位。沿氧化带前锋方向，铀矿体主要定位于氧化砂体变薄或尖灭部位，矿体走向及平面展布形态与氧化带发育方向基本一致。%Provenance ,uranium source and their convergence process in Mengqiguer uranium deposit in the southern margin of Yili basin ,Xinjiang was discussed to show their restriction on the uranium metal‐lization in sandstone.By comparing the heavy mineral assemblages , the REE distribution patterns of the sediments in target layer and the typical rocks in provenance area , the sediment sources of target layer was discovered mainly acidic granite with high active uranium which acted as the uranium source. Along the sedimentary path of target layer , uranium orebody occurs firstly at the location where there is an ab‐rupt change of sandbody thichness , increase of muddy intercalation and grain size from coarse to fine etc. Along the direction of oxidation front movement , the uranium ore body was mainly located at place where the oxidized sand being thin and the orebody strike was similar to the movement direction of oxida‐tion zone.