准噶尔盆地南缘楼庄子矿产地铀矿化特征及其成因指示OA

Louzhuangzi mineral occurrence is a newly recognized exploration discovery in recent years at the southern margin of Junggar Basin.No oxidized alteration zone has been found in Louzhuangzi mineral occurrence,and its uranium orebodies are all hosted within the grayish-white alteration zone,differing from the typical interlayer oxidation zone-type(or the roll-front type)sandstone-hosted uranium deposits.At least two different genesis models have been proposed,namely the"traditional interlayer oxidation zone-type mineralization with later strong uplift"and the"deep-sourced hydrocarbon-bearing fluid involvement plus two-stage mineralization".In this study,ore samples from four drill holes have been systematically collected,and thin-section petrographic observation,scanning electron microscopy(SEM),and electron probe microanalysis(EPMA)were performed,together with the whole-rock clay alteration analysis.The uranium minerals and their associated mineral assemblages have been summarized,and the characteristics of the grayish-white alteration and uranium mineralization were further analyzed and demonstrated.The results show that uranium in the Louzhuangzi mineral occurrence mainly occurs as two independent minerals—pitchblende and coffinite,together with abundant titanium-uranium mixtures.Uranium mineralization has a close spatial relationship with pyrite,carbonaceous debris,and bitumen,which exhibits both similarities and differences with the typical interlayer oxidation zone-type sandstone-hosted uranium deposits.At least a two-stage mineralization fluid activities,namely the traditional oxidized fluids and reduced hydrocarbon-bearing fluids are believed to take place in Louzhuangzi mineral occurrence.