Tratamento e interpretação de dados geoquímicos de solo das folhas SB-25-V-C-IV (João Câmara) e SB-25-Y-A-I (São José do Campestre), Rio Grande do Norte

Abstract

The João Câmara (SB-25-VC-IV) and São José do Campestre (SB-25-YAI) map sheets, comprise the northeast part of the São José do Campestre Domain, from the Borborema Province. This area has a high exploratory potential, considering the history of mineral extraction in the region and, therefore, this work seeks to determine sections of economic interest from the geochemical soil analysis. In order to accomplish that, using the geochemical survey of 400 sampling stations in the area carried out by CPRM, we selected 21 elements that represent the type of mineralization most likely to occur in the area (Al, Ba, Be, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Nb, Ni, Pb, Rb, Sn, Th, V, W and Zn). For each of these elements the study of the quality of the datasets was performed, based on the analytical results of duplicate samples collected in part of the sampling stations, and the most important statistical parameters for the description of the data were calculated. Since these datasets met expectations of sample quality, they were studied to determine which concentrations represent anomalies in the geological context of the area. Initially, geochemical relief maps were created using three methodologies for the hierarchization of categories: the use of percentiles, the elements from the boxplot diagrams and the calculation of the median absolute deviation, or MAD. In addition, trend surfaces were calculated in order to generate residue maps to help identify anomalies. The four maps resulting from the previous processes were then used in the production of unielemental anomaly maps. The Spearman correlation coefficient between the elements was also calculated to support the interpretation of the products. Finally, all the material was integrated and interpreted, determining sections with geochemical associations that may represent the presence of mineralized bodies.