钱家店铀矿床表生含氧含铀流体与深层酸性含烃流体的耦合成矿作用——来自岩心蚀变矿物填图的证据

以岩心光谱蚀变矿物填图为主要研究手段,结合野外地质编录、偏光显微镜、扫描电镜、电子探针能谱分析、氢氧同位素测试等方法,对开鲁盆地钱家店砂岩型铀矿床85个有效钻孔岩心开展了系统的蚀变矿物填图和矿物学研究。结果表明:①主要含矿层上白垩统姚家组蚀变矿物主要有黏土矿物(高岭石、蒙脱石、伊利石、伊/蒙混层及局部绿泥石)、铁的三价氧化物、黄铁矿、碳酸盐(方解石、白云石、铁白云石)等,它们呈现明显的分带特征:氧化带为高含量的"高岭石+Fe³⁺氧化物"组合、过渡带为中等含量的"高岭石+蒙脱石(伊/蒙混层)"+高含量的"黄铁矿+铁白云石"组合;还原带则主要为高含量的"蒙脱石(伊/蒙混层)+伊利石+黄铁矿"组合,矿体主要分布在氧化-还原过渡带和高岭石变化的梯度带上,并见有明显的高岭石、黄铁矿、铁白云石富集。②含氧含铀流体主要来自于WS、WN方向,其次为ES方向(也可能是WS向流体的分支),酸性含烃流体主要来自于NE向的断裂构造,流体温度介于40～120℃,两种不同性质流体的耦合作用是该地区的主成矿作用。③主成矿事件应发生在白兴吐"天窗"构造隆升之后,构造天窗在成矿系统中主要承担着还原...

Uranium Mineralization of Coupled Supergene Oxygen-Uranium Bearing Fluids and Deep Acidic Hydrocarbon Bearing Fluids in the Qianjiadian Uranium Deposit,Kailu Basin

A systematic alteration mineral mapping and mineralogical studies were carried out on 85 borehole cores from the Qianjiadian sandstone-type uranium deposit in the Kailu Basin by using core spectrum scanning technique,combining with field geological logging,microscopy,scanning electron microscopy,electron probe energy spectrum,hydrogen and oxygen isotope analyses.The hydrothermal minerals in the upper Cretaceous Yaojia Formation show zoning signature and are dominantly composed of clay minerals(kaolinite,smectite,illite,illite/smectite mixed layers and a small amount of chlorite),ferric oxide,pyrite,and carbonate(calcite,dolomite,ankerite).The oxidation zone is characterized by high content of kaolinite and ferric iron oxide,while the transition zone is featured by kaolinite and smectite(illite/smectite mixed layers)and high contents of pyrite and ankerite.On the contrary,the reduction zone consists primarily of smectite(illite/smectite mixed layers),illite,and pyrite.The uranium ore bodies mainly occur in the oxidation-reduction transition zone and the kaolinite gradient zone with significant accumulation of kaolinite,pyrite,and ankerite.The oxygen-and uranium-bearing fluids dominantly sourced from WS and NW,and less from ES(which can be considered as branch of WS fluid).Acidic hydrocarbon bearing fluids mainly channeled through NE-oriented fracture structures.Fluid temperatures are inferred to be 40–120℃.The coupling of the two different types of fluids is the main factor triggering the mineralization in this area.The main stage of ore mineralization likely occurred subsequent to the uplift of the Baixingtu structural inlier.The Baixingtu structural inlier acted as a reduction barrier and controlled the groundwater drainage.