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美国已开采的大多数铀矿石都沉积于河相砂岩的还原一氧化界面上,这是由于黄铁矿碳质相经受氧化的结果。在成矿过程中形成大的氧化蚀变舌状体,其范围从地表向下延伸到还原相。地表上的放射性和点状矿化反映深部有矿体存在,但在没有这种显示的地区,在红色或淡褐色砂岩露头中能测得的其他特征,也能用来评价矿石的有利性。天然残余磁性的特性(如异常磁极的方向或者在始新世或古老河相红色砂岩层中不存在残余磁性)可反映导致深部成矿的较新近的氧化作用。在新近氧化砂岩中未观察到磁铁矿和磁赤铁矿,这是由于在成矿过程中,这些铁的氧化物被还原或淋滤。地表的石膏,全岩样或地下水中稀见的硫酸盐硫的负δ~(34)S值可以指示深部有与铀矿共生的富含~(32)S的黄铁矿存在。
Most uranium ore mined in the United States has been deposited on the reduced-oxidation interface of fluvial sands due to the oxidation of the pyrite carbonaceous phase. In the process of mineralization, a large oxidized alteration tongue is formed, extending from the surface down to the reduction phase. Radioactive and point mineralization on the surface reflects the presence of deep ore bodies, but in areas without this indication other features that can be measured in red or light brown sandstone outcrops can also be used to assess the ore’s benefits. Properties of the natural residual magnetism (such as the direction of anomalous poles or the absence of residual magnetism in Eocene or paleo-sands red sandstone layers) may reflect the more recent oxidation leading to deep mineralization. Magnetite and maghemite were not observed in newly oxidized sandstones because of the reduction or leaching of these iron oxides during mineralization. The negative δ ~ (34) S values of the rare sulphate sulfur in surface gypsum, whole rock sample or groundwater can indicate the existence of ~ (32) S rich pyrite enriched in uranium deposits.