Mapeamento geológico da Bacia de Alagoinha do Piauí e ocorrências minerais associadas, Piauí - Brasil

Abstract

The growing demand for copper and iron ores, fueled by the growth in the production of electric cars and associated with the continuous growth of the Asian market, makes the demand for these ores even greater, raising the value of these commodities. Therefore, in order to meet the market demand, it is necessary to carry out geological mapping in areas that present a suitable geological environment for the occurrence and accumulation of these ores. The present work consisted of a semi-detail scale mapping of 1:40,000 in the basin, called in this work, Alagoinha do Piauí – Piauí, Brazil. This work aimed to characterize thebasin and its contact relationships with the basement, as well as to map and characterize mineral occurrences present in the region. In order to achieve the listed objectives, several stages were carried out, the pre-field stage being composed of preliminary maps and bibliographic surveys, where scientific articles, course conclusion works and cartographic bases were consulted, the field stage consisted of the a team in the field with the aim of analyzing outcrops, collecting samples and collecting structural measures, so that in the post-field stage, treatments of the collected data were carried out and their compilation, aiming at the preparation of this report. Two gutters of the Alagoinha do Piauí Basin with EW orientation were mapped, with the gutter more to the NE being partially covered by the Serra Grande Group, the basin is composed essentially by poorly selected polymictic conglomerates and mostly clast supported with a sandstone matrix of predominant quartz composition, the source of the clasts comes from the Orós Group, this group is composed of two lithologies, these being the orthogneiss and metavolcanic rocks, the main hydrothermal alterations in the area are related to the Orós Group with the presence of k-feldspatization, silicification, epidotization. Occurrences were mapped of malachite, chalcopyrite, hematite and magnetite, an important shear zone was also identified in the area (ZC Alagoinha). Finally, this work concluded a sequence of mappings of the transition basins of the extreme east of Piauí, the Alagoinha do Piauí Basin has its geometry influenced by the Alagoinha ZC, the existing mineral occurrences are not concentrated in the gutters but in the basement rocks, mainly associated with structures of the important dextral shear zone that houses magnetite bodies along the zone, as well as the occurrence of hematite and chalcopyrite and malachite.