The main geological types of uranium deposits in Argentina

Full text: The uranium-related activities in Argentina begun in the 1950s and, as a result of the systematic exploration, several types of deposits have been discovered since then: volcanic and caldera-related, sandstone-hosted, vein spatially related to granite (intragranitic and perigranitic) and surficial. The deposits those which have been objectives of the most important uranium exploitations are the ones that belong to the volcaniclastic type, which are localized in Permian formations associated with synsedimentary acid volcanism in the Sierra Pintada district (Mendoza province). The current identified resources are 4 420 t U recoverable at a cost below US$130/Kg U. Several important uranium mineralisations have been identified in Cretaceous fluvial sandstones and conglomerates, among which the most relevant is the Cerro Solo deposit (Chubut province). The mineralized levels there are 0.5 - 6 meters wide and 50 - 130 meters deep. The identified resources totalise 11 220 t U at 0.4 % U, included in the < US$130/Kg U cost category. The uranium mineralisations in veins and disseminated episyenites within peraluminous leucogranites of the Sierras Pampeanas (Cordoba and San Luis provinces) represent other types of existing deposits. These granites are Devonian - Carboniferous and the related deposits are comparable to those from the Middle European Variscan chain. There is also another vein-type uranium deposit located in a metamorphic basement in the periphery of high potassium calcalkaline granites (Las Termas deposit, Sierras Pampeanas Noroccidentales, Catamarca province). The mineralization control is mainly structural and the speculative resources have been evaluated in 1 500 t U at a grade of 0.3% U. More recently, the pedogenetic calcrete type has been studied in the area of Laguna Sirven (Santa Cruz province). The speculative resources there are about 1 000 - 1 500 t U at 200 ppm U. Finally, it can be pointed out that the existence of favourable basins and different uranium mineralization models configure promising conditions to develop new uranium resources. In this context, the uranium deposits related to continental sandstones appear as the most interesting exploration targets in the country. (author)