Time, crustal evolution and generation of uranium deposits

In the 35 years following the awakening of interest in uranium and its uses major deposits of the element have been identified in several distinctly different geological environments. Numerous geological descriptions of these major types of uranium deposits have been provided, as well as many discussions and interpretations of the processes that are involved in their genesis. It is not so well recognized, however, that these deposits and genetic processes have undergone time-dependent evolutionary changes from Archaean to Caenozoic time. The purpose of this paper is to review briefly the descriptive geology of these deposits and the current views concerning their origin, and particularly to outline the evolutionary changes that have controlled their distribution in space and through time. Especially emphasized are the evolutionary changes in source of uranium, uranium transport mechanisms and depositional processes that have shaped the different major types of uranium deposits throughout the geological record. (author)