柴北缘冷湖砂岩型铀矿铀矿物赋存特征及成因机制

冷湖铀矿床是近年来在柴达木盆地北部新发现的具有工业价值的砂岩型铀矿床,为了研究该地区铀矿物的类型、成分特征、赋存形式及铀成矿作用,本文在野外地质调查的基础上,对下侏罗统小煤沟组相关蚀变矿物进行了矿相学、电子探针、背散射电子成像分析.研究发现,冷湖小煤沟组矿石主要包括杂砂岩型及碳质砂岩型两种,整体发育后生蚀变.铀矿物主要...

Genetic mechanism and occurrence characteristics of uranium minerals in the Lenghu sandstone-type uranium deposit, northern Qaidam Basin

Lenghu uranium deposit is a newly discovered in recent years and have industrial value sandstone-type uranium deposit in the northern part of the Qaidam Basin.In order to study the classification,occurrence and mineralization of uranium minerals in this area,this paper conducted the mineralogical,electron probe,backscatter electron imaging analysis of the altered minerals in Xiaomeigou Formation of Lower Jurassic on the basis of field investigation.These studies found that the ore types of Xiaomeigou Formation in Lenghu are mainly composed of complex sandstone-type and carbonaceous sandstone-type,which have occurred overall epigenetic alteration.It is found that the main uranium minerals are uranite,pitchblende and minor of lead selenite,which is closely associated with clay minerals,organic matter,and pyrite,and lie in the intergranular space of quartz,feldspar and other altered lithic mineral grains or in cleavage joints of altered minerals occurs in fine columnar,gel-like or irregular sawtooth shape.In late multiple fluid processes,U⁶⁺ occurred reduction-precipitation-adsorption uranium mineralization in the reduction environment provided by Fe²⁺.Based on the analysis of high Y and low Y-types uranium minerals,alteration sequence and environmental characteristics,it is inferred that uranium in uranium minerals was the residual of original uranium minerals,which is enriched and mineralized by multi-stage transformation of fluids with no Y element or very low Y element.