钱家店铀矿床多期叠加改造成矿的关键制约因素OA

[Objective]Research on the metallogenesis of sandstone-type uranium deposits often focuses on interlayer oxidation,while neglecting the roles of synsedimentary environments and post-mineralization superimposed transformation.This poses significant challenges to uranium exploration and in-depth understanding of regional metallogenic regularity.The Qianjiadian uranium deposit is a typical multi-stage metallogenic deposit,providing an excellent case for studying the key ore-controlling factors in different metallogenic stages.[Methods]In view of this,this study identified the key factors related to the formation of this deposit,including sedimentary environment,interlayer oxidation,and hydrothermal activity,through core observation,polarizing microscopy,scanning electron microscopy(SEM),and grain size analysis.The main uranium-bearing rock series of the Qianjiadian uranium deposit are dominated by a braided river delta sedimentary system.[Results]In the northeastern part of the mining area,there are long-term waterlogged interdistributary bays,characterized by the concentrated development of dark mudstones.Epigenetic oxidation in interlayer oxidation is represented by red sandstones and yellow sandstones,with uneven red coloration that often cuts through bedding.Along the direction of interlayer oxidation,the rock types appear in the following order:red sandstone → yellow sandstone → gray-white sandstone → gray ore-bearing sandstone→primary gray sandstone.Hydrothermal activity is represented by the occurrence of hydrothermal mineral assemblages such as scheelite-brannerite-chalcopyrite-sphalerite-galena-ankerite in uranium reservoirs.On this basis,the relationships between sedimentary environment,interlayer oxidation,hydrothermal activity,and uranium metallogenesis were discussed.It is pointed out that the sedimentary environment exerts a certain degree of constraint on uranium metallogenesis,and uranium orebodies are mainly distributed in the transition zones from braided distributary channels and crevasse deltas to long-term waterlogged interdistributary bays.Interlayer oxidation has an obvious constraint on uranium metallogenesis,and the uranium orebodies are mainly concentrated in areas where the ratio of oxidized sand bodies ranges from 10％to 20％.Hydrothermal activity related to basic rock intrusion is involved in uranium metallogenesis,leading to the enrichment of uranium.The Qianjiadian uranium deposit has experienced three stages:synsedimentary oxidation pre-enrichment stage,interlayer oxidation convergence metallogenic stage,and hydrothermal superimposed enrichment stage.[Conclusions]Long-term waterlogged valley depressions or interdistributary bays,redox transition zones and,areas affected by hydrothermal activity related to basic rocks are targets for prospecting high-grade orebodies.The research results lay a foundation for the study of the metallogenesis of the Qianjiadian uranium deposit and regional uranium metallogenic regularity.