Use of radiogenic heat for demarcation of hydrothermal alteration zones in the Pernambuco-Brazil

Abstract

In this paper, we identify hydrothermal alteration zones that are located at the eastern extreme of Borborema Province, Pernambuco State, using radiogenic heat, in combination with magnetic and radioelement data collected both from the air and on the ground. The use of these methods enabled the mapping of geological lineaments based on total magnetic intensity maps, radioelement concentration maps, ternary maps and the F factor, as well as physical properties provided by ground data (thermal conductivity, density, and magnetic susceptibility). The data integration was based on low values of radiogenic heat and high K concentrations, as well as high F factors, amplitudes of the analytic signal, and K/eTh and eU/eTh values. These characteristics occur within the Pernambuco lineament and within other features to the southeast, a short distance south of the lineaments, which are made up of units including a migmatitic gneiss complex, as well as the Modern, Itaporanga and Sierra Passira Intrusive Suites. In these areas, elongated sources that are consistent with lineaments were identified. These sources were assigned depths of up to 3km and are 5–10km long, with the most significant extending SE-NW. These areas are favorable for the mineralization of iron, titanium and nickel. As the results are satisfactory, such areas can be studied in detail in the future.