Mapeamento geológico da porção sudoeste do Município de Pio IX - Piauí

Abstract

In the geologic mapping executed in a 150 km2 area, in a 1: 25.000 scale, on the southwestern quadrant of the Pio IX chart, settled on Piauí state, had been disclosed Units of Paleoproterozoic and Silurian ages. These Units had been defmed, from base to top as: São Nicolau Complex, Orós Group, Sin to post-tectonics Granites, Rio Jucás Group and Serra Grande Group. The execution of this work made possible the identification of two small occurrences of mineralized hydrothermalized breccias in iron and copper, those associated to the acid metavolcanics rocks of the Orós Group. Those mineralizations arise proximately by the ledges of the molassics basins located in the SW and SE portions of the area. The iron mineralized breccias occupy an area of approximately 2 km2 and present structures in stockwork pattern with the iodes filled by silica and iron oxide. The copper mineralized breccias occur in an approximately 300 m2 area, with structure in stockwork pattern and still locally spread, the Iodes are filled by quartz and copper carbonates (malachite). The genesis of those mineralizations is probably related to a shallow epithermal environment.