柴达木盆地北缘东部中新统上油砂山组沉积相特征及其与铀成矿关系OA

Recently,several Cenozoic sandstone-type uranium occurrences have been successively discovered along the northern margin of the Qaidam basin.Taking the Upper Youshashan formation of the Miocene series as the target horizon,this study integrates field mapping,core logging,sedimentary architecture and geochemical analyses to elucidate the sedimentological controls and metallogenic mechanism of uranium mineralization.The Upper Youshashan formation sandstones are predominantly lithic arkoses and feldspathic litharenites,formed during a depositional stage governed by a cold-arid paleoclimate.The sedimentary environment was dominated by braided river delta front deposits,and the sand bodies generally exhibit a positive cyclicity characterized by"coarse at the bottom and fine at the top".The subaqueous distributary channel microfacies,as well as the transitional microfacies between subaqueous distributary channels and interdistributary bays,provide favorable locations for the enrichment of uranium mineralization.Sand-body thickness and sedimentary microfacies dictate the spatial distribution of mineralization,whereas the high connectivity of the reservoir sandstones provided efficient conduits and traps for ore-forming fluids.This research result can provide a theoretical basis and practical reference for subsequent uranium resource exploration in the region.