Commercial Types of Uranium Deposits
The term “commercial deposits” means the deposits which are stable suppliers of uranium feedstock and account for at least 1% of the world uranium output.
Pursuant to IAEA classification developed in 1988 — 1989 all known uranium deposits are divided into 16 geologic and commercial types (GCT), three of which today dominate in uranium production:
- arenated deposits where uranium mineralization is associated with ancient continental and littoral sea sands and sandstones (deposits in Kazakhstan, Namibia, Niger, USA, Uzbekistan);
- “unconformity” type where mineralization is associated with zones of structural and stratigraphic unconformity between sedimentary rock of late Proterozoic age and intentsively altered rock of crystalline basement of Archaean age and early Proterozoic age (Canada, Australia);
- breccia type where ores are uranium rich hematite breccias of igneous and intrusive rocks (Australia).
About 60% of the world measured resources of uranium are concentrated within deposits of the abovementioned commercial types. However, other types of commercial deposits play a substantial role in the resource base in some countries — conglomerate in the South African Republic, igneous in Russia, intrusive in Namibia.
Classification of commercial types offered by IAEA is convenient for practical purposes but is inconsistent with the systemic principle. In Russia there are endogenous and exogenous deposits of uranium whose GCT are classified on the basis of the principle of deposit association with certain types of continental structures of the Earth crust. There are the following main geological and commercial types of deposits:
- uranium deposits in the areas of orogenetic activation of Pre-Cambrian shields (Ukraine, Namibia, Russia);
- gold-nickel-uranium deposits in the zones of carbonate-magnesian metasomatism close to surface of unconformity of various structural lifts (Canada, Australia);
- deposits occurring in structures of orogenetic activation of folded areas (Kazakhstan, Germany, Czech Republic);
- deposits in igneous tectonic structures of late orogenic or activated stages of development of folded areas (Russia);
- deposits occurring in marine clays of platform mantle (Kazakhstan);
- deposits occurring in permeable strata of platform mantle (Uzbekistan, Kazakhstan, Russia, Ukraine, USA);
- complex uranium bearing deposits (SAR, Brazil, Australia).