PROSPECÇÃO DE URÂNIO NO ESTADO DE GOIÁS

Resumo

Nuclam started in 1977 a reconnaissance project in central Goiás based on previous work carried out by CNEN and Nuclebrás. The main motivation has been the similarity in regional geology to areas of Canada and North Australia where some years ago important uranium deposits have been found. Systematic prospecting by means of various technics ranging from regional to detailed scale have been carried out from 1978 to 1980 with promising results. In the Northwestern part of the project area a pegmatite type Uranium mineralization has been localized, which is characterized by low grade and small tonnage. More favourable are the mineralizations encountered in the South and West of Campos Belos. They are related to faults and cataclastic schists, formed out of basement rocks by shear tectonics of the Uruaçuan orogenetic cycle (structure controlled mineralization). Another promising mineralization has been encountered recently, further to the West, in migmatitic rocks of the basement. The host rock is characterized mainly by a high amount of albite feldspar and only traces of quartz which points to Na-metasomatic events as source of uranium. The metasomatism apparently started during the Uruaçuan Cycle and has been still active post-tectonically. The lithologically and structurally controlled mineralization is spread out over an area of ca. 6 x 1,5 km. The field work is still in the preliminary phase, thus final results have not yet been obtained. The finding of the metasomatic mineralization type in Goiás is the first located in central Brazil.