什么是 Unconformity-related and roll-front uranium deposits？

An unconformity-related uranium deposit is a body of pitchblende and uraninite filling fractures and breccias in metamorphosed carbonaceous pelites and in the quartz arenites above them, below, above or across an unconformity between Early and Middle Proterozoic rocks in an intracratonic basin. A roll-front uranium deposit is a crescent-shaped body of uranium minerals that cuts across the bedding of a feldspathic or tuffaceous sandstone at the boundary between oxidized and reduced ground, where uranium was deposited in a locally reduced environment, among pyrite.