THE BRASÍLIA FOLD BELT AGROMINERAL (P/K) DEPOSITS: GEOLOGY, CARACTERIZATION AND POTENTIAL
Verdete, Coromandel Deposit type, Vazante Group, Bambuí Group.
Due to the high human fertilizers consumption need, it is necessary to expand the geological knowledge about these deposits, especially those of phosphorus and potassium. Nowadays, Brazil heavily depends on the external importation of these inputs, which are of high economic and strategic value, and this dependence represents one of the greatest weaknesses of the national agribusiness sector. Within the national production scenario, the potential of deposits associated with Proterozoic basins, especially those hosted in the Brasília Fold Belt, lacks more specific studies aimed to characterizing the deposits and proposing metallogenetic models that allow the discovery of new favorable exploratory areas. Thus, the present work has as main objectives the evaluation of the metallogenesis and potential of the phosphatic deposit of Coromandel-MG region and potassic deposit of Cedro do Abaeté-MG, which were less covered by the classical literature and, subsidiarily, to contribute with its geological setting at the belt. From the new field data, mineralogy, aerogeophysics and geochemistry it was possible to propose the Cedro do Abaeté potassic deposit as a result of potassium metasomatism caused by the circulation of fluid from deep alkaline intrusions. Likewise, based on the data collected at the region of Coromandel-MG, a systematic petrographic description of the main lithologies associated with the phosphate deposit and its faciological framework was feasible. The sedimentation environments were interpreted from the faciological associations and corroborate with a glaciomarine system, where all physicochemical variables essential for the precipitation of minerals from the phosphatic assembly were directly controlled by the glacier and its immediate surroundings, besides the presence of paleo valleys, shallow water conditions, facies interfingering and continental phosphorous sources.