金塔盆地北缘野马井地区东部凹陷砂岩型铀成矿条件综合分析OA

The eastern sag in the Yemajing area of northern Jinta basin is a typical intermontane depression,where the uranium geological research is currently limited.To explore the uranium mineralization potential of small depressions surrounding uranium-rich pluton,this study systematically analyzed the sandstone-type uranium metallogenic conditions in this area using comprehensive techniques including geological profile surveying,ground gamma spectrometry,electromagnetic survey,areal soil radon gas measurement,trace element analysis,and scanning electron microscopy.The results show that uranium-rich Carboniferous monzogranites(surface grab samples uranium content up to 102×10-6)are widely exposed around the depression,and the Lower Cretaceous Xiagou formation itself exhibits pre-enrichment uranium characteristics,indicating superior uranium source conditions.The depression as a whole exhibits a synclinal structure developed within a"U"-shaped catchment configuration.The Xiagou formation has a"mud-sand-mud"sequence,with vertical sandstone thickness generally ranging from 40 to 260 m,and the epigenetic alterations are dominated by phreatic oxidation and surface leaching.The surface radioactivity is high(average uranium content of sandstone 91.9×10-6,maximum 217×10-6),and the soil radon anomaly is of extensive area.Uranium and associated minerals such as pitchblende,anatase,and thorianite can be identified in surface ores.The above findings confirm that this depression has favorable uranium metallogenic conditions,with the mineralization type being sedimentary-diagenetic plus phreatic oxidation(basal paleochannel type),but the mineralization scale may be limited.This research provide a reference for sandstone-type uranium exploration in similar small basins(depression zones)in northwestern China.