Mapa de favorabilidade para ocorrência de Elementos Terras Raras (ETR) e levantamento radiométrico na porção norte do batólito de Acari, centro-oeste do Geoparque Seridó

Abstract

The global demand for rare earth elements (REE) has been increasing in recent years, as these elements are widely used in the high-tech industry. The search for this strategic mineral in Brazil has become essential for the development of the national industry, especially for automotive companies. In this context, the creation of a favorability map is an indispensable tool to indicate the most favorable zones for exploration. Since the Seridó region, in the State of Rio Grande do Norte (RN), northeastern Brazil, contains high-value mineral provinces, this study aimed to develop a favorability map for potencial REE occurrences in the northern portion of the Acari granitic batholith, located in the west-central area of the Seridó Geopark. The materials used included geological, geophysical, and geochemical data available from the Geobank of the Geological Survey of Brazil, corresponding to the Currais Novos Sheet (SB.24-Z-B-II, 1:100,000 scale), from which preliminary evidential maps were generated. These maps were integrated using map algebra toolset in ArcGIS™ software, resulting in the REE favorability map for the Currais Novos Sheet. After identifying the most favorable zones north of the municipality of Acari, a new target area was delineated for further studies and field work validation. In the fieldwork stage, geophysical prospecting was conducted using gamma ray spectrometry with a scintillometer (RS-220 super-IDENT) to evaluate the radiometric properties of rocks. The survey was carried out along an approximately E-W profile over the northern portion of the Acari granite and two N-S profiles along river drainages west of the granite — potential placer deposits with high concentrations of REE, adsorbed by the clay minerals in the soil. This radiometric method validated the zones of highest favorability indicated in the initial map. Additionally, samples were collected from the drainages for X-ray fluorescence analysis, although the results were inconclusive. Therefore, further sampling and geochemical analysis using ICP are recommended for future studies, which remains a target of interest for REE exploration.