Análisis petrográfico y por Sem-Eds de la mineralización secundaria de uranio en el basamento del depósito Ivana (U-V), macizo Nordapatagonico, Río Negro.

Abstract

The essential objective of this final first degree project (Geology-UNRN) is to study the petrographic features characteristics of secondary uranium mineralization in the igneous-metamorphic basement of the Ivana (U-V), deposit located in the extreme northeast of the North Patagonian Massif, Río Negro. This basement is made up of granites from the Navarrete Plutonic Complex (Permian) and metamorphic rocks from the Nahuel Niyeu Molding (Cambrian). In the subsoil, in addition, a regolith cover develops on these rocks. For this study, it was used the rock cutting From air reverse (RC) drilling holes, as well as geological, geophysical and geochemical data From the holes and sampling pits; information supplied by the Minera Cielo Azul company. Maps and 2D sections, were prepared and petrographic descriptions of the cutting of the granites, phyllites and meta-sandstones and of the uranium-bearing secondary mineralization, with a stereoscopic microscope (magnifying glass lens). The mineralogical-textural analysis of the set was complemented with scanning electron microscopy studies (SEM). Based on the comprensive analysis of the petrographic and SEM data, it was possible to determine that the basement rocks, and preferently their regolith, at the Ivana deposit are mineralized with uranium mineral species, hereinafter MU, represented by vanadates, silicates and carbonates. In this sector of the deposit, some elements were identified such as iron oxides, clay minerals and components of organic origin that would have acted as reducing agents in the precipitation of uranium in solution, establishing a redox front and allowing the aforementioned mineralization. That process would have been favored by a structural control present in the basement, which allowed the circulation and accumulation of groundwater rich in uranium ions in sectors with greater porosity and permeability. Finally, it is discussed the possibility of a mixed source for the U of the Ivana deposit, composed of the igneous-metamorphic rocks of the basement and the tuffs of other geological units associated with the sedimentary cover.