INTEGRATED INTERPRETATION OF GEOLOGICAL AND GEOPHYSICAL DATA FROM THE POTIGUAR BASIN BASEMENT: IMPLICATIONS FOR CRUSTAL STRUCTURE AND GEOTHERMAL POTENTIAL
Borborema Province; Potiguar Basin Basement; Crustal Boundary; Jaguaribeano Domain; Rio Piranhas–Seridó Domain; Geothermal Energy.
In the global context of the urgent search for low-carbon energy sources, geothermal energy stands out as a renewable, low environmental impact option capable of providing a continuous supply, independent of climatic conditions. In Brazil, the identified geothermal potential is predominantly low enthalpy, and its current use is mainly limited to direct applications such as leisure and recreation in thermal spa facilities, including exploitation in the city of Mossoró, Rio Grande do Norte, among others. However, recent studies indicate the possibility of medium-temperature geothermal resources at depths between 3 and 5 km in northeastern Brazil. This study aims to integrate geological and geophysical data in order to investigate the geological framework of the southern portion of the Potiguar Basin basement, with the objective of providing a geological characterization and a preliminary assessment of its geothermal potential. Geological data consists of basement cuttings from wells located in the Potiguar Basin, subjected to petrographic analysis, X-ray diffraction (XRD), and U–Pb geochronology, in addition to macroscopic descriptions of core samples. Geophysical data include ground and airborne gravimetry and high-resolution magnetometry, processed using vertical derivative and horizontal gradient filters to enhance structural anomalies. Geological maps and literature data were used to correlate basement lithotypes intersected by wells with surrounding outcropping units. Geochronological results initially allowed the identification of two main rock groups: (1) Paleoproterozoic orthogneisses, with ages ranging from 2.273 to 2.360 Ga, subsequently correlated with the Caicó Complex (Rio Piranhas–Seridó Domain); and (2) Neoproterozoic granitoids, with ages between 570.7 and 579.7 Ma, correlated with the Itaporanga and Dona Inês Intrusive Suites. The only well with core data, characterized by migmatites, was attributed to the Jaguaretama Complex. The Paleoproterozoic orthogneisses display preserved igneous structures, mineral assemblages consistent with calc-alkaline magmatic series, and a low degree of migmatization, distinguishing them from the strongly migmatitic rocks of the Jaguaretama Complex. Processed magnetic and gravity datasets highlight lineaments associated with the NE–SW-trending Portalegre Shear Zone and its continuation into the basin, as well as NW-trending structures related to the Apodi Fault. The integrated interpretation of geological and geophysical data enabled the delineation of the crustal boundary between the Jaguaribeano and Rio Piranhas–Seridó domains within the basin, positioned over an internal basement high. The results provide a foundation for estimating the geothermal potential of the Potiguar Basin basement, through comparison with studies in the literature which present geothermal property data for rocks analogous to those identified in this work, an analysis that remains to be conducted.