The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

Abstract

We present a combined analysis of airborne geophysical data (magnetics and gamma-ray spectrometry) and field aspects of Itapetim lode gold district region, aiming to identify structurally deformed and hydrothermally altered zones, which are suggestive of gold mineralized sectors. The main geophysical lineaments are oriented in the NE-SW and E-W directions and display a clear correlation with the major gold-bearing structures in the region. In the magnetic maps, the key pathfinder for gold occurrences is their association with strongly magnetized areas positioned along the Itapetim Shear Zone and outer contour of Teixeira Batholith. In the field, such structures are materialized in protomylonitic and mylonitic rocks that present evidence of ductile and brittle deformation, whereas kinematic criteria are suggestive of a transpressional tectonic regime. In addition, the main radiometric pattern is characterized by K enrichment, which is correlated with a hydrothermal mineral assemblage dominated by quartz, potassium feldspar, and tourmaline. Based on the obtained data integration, we produced an integrative map and located ten new target areas of possible gold mineralization, which is correlative to other well-known lode deposits in Northeast Brazil and Africa.