鄂尔多斯盆地北部古水文地质条件与铀成矿前景分析

Analysis on paleohydrogeologic conditions and prospects of uranium metallogenesis northern part of Ordos basin

本文分析了鄂尔多斯盆地的古水文地质、古气候及地质构造的演化过程 ,认为现在为开放式盆地的鄂尔多斯盆地在渐新世以前具典型的渗入盆地特征。突破了前人认为该盆地为开放式盆地 ,不利于铀成矿的评价结论。其古水文地质条件、古气候条件及地质构造条件对发育区域层间氧化带非常有利 ,层间氧化带的发育期和主成矿期自中侏罗世晚期至始新世末 ,持续时间达 115Ma。圈定的古层间氧化带前锋线 ,经钻探验证 ,具良好的含矿性 ,未来该地区有望成为我国一个新的铀矿资源基地。

The evolution of paleohydrogeology, paleoclimate and geologic structure of the Ordos basin show that it is an infiltration basin before Pliocene time, though it is an open basin now. This point of view is different from the previous conclusions that regarded the Ordos basin as an unfavorable one for the formation of uranium oredeposits. Actually, paleohydrogeologic conditions, paleoclimatic environments and geologic structure of the basin were quite favorable for the development of regional interlayer oxidation zone. The development time of paleo interlayer oxidation zone and main uranium ore formation period continued from the late stage of Middle Jurassic up to the end of Eocene with the time interval of 115 Ma. The inferred paleo redox front has been verified by drilling and it shows good uranium mineralization. The area expects to be a new base of sandstone hosted uranium resources in China.