Caracterização geológica, faciológica e modelagem aerogeofísica do corpo granítico Davinópolis, sudeste de Goiás.

Abstract

The study area, located in the municipality of Davinópolis - GO, is situated in the southern portion of the Brasília Fold Belt, where several lithologies belonging to a supracrustal sequence crop out, corresponding to the Araxá Group and the Abadia dos Dourados Complex. Intruded into these metasedimentary and metamafic rocks lies the granitic body known as the Davinópolis Granite, which is associated with a series of magmatic episodes that gave rise to a total of fourteen (14) intrusions between the cities of Araxá (MG) and Catalão (GO). The Davinópolis Granite is described in the literature as an A-type, alkaline granite, formed in an anorogenic setting, with a crystallization age of 775 ± 5 Ma, and mineralogically composed of aluminous minerals such as muscovite and garnet, displaying a slightly metaluminous to peraluminous character. However, its genesis and characterization remain poorly constrained due to the scarcity and inconsistency of available data. In this context, the present study aimed to improve the understanding of the true spatial extent of the body, as well as to detail its mineralogical characteristics, genesis, and possible geological evolution. The adopted methodology integrated systematic geological mapping at a 1:30,000 scale, petrographic analyses, and the interpretation of airborne geophysical data (magnetometry and gamma spectrometry), in addition to 2D and 3D modeling of the anomalous magnetic field. Four facies associations were recognized (muscovite-bearing monzogranite, fine-grained syenogranite, dark-gray granite with epidote and allanite, and granodiorite with epidote and allanite), composed mainly of quartz, microcline, oligoclase, biotite, garnet, and muscovite. The separation criterion relied on color (light and dark associations) and the occurrence of anomalous concentrations of accessory minerals such as allanite, epidote, and titanite, interpreted as hydrothermal enrichment. The geophysical data allowed the delineation of the granite’s contacts, depth estimation, compositional characterization, and identification of regional structures. The intrusion reaches approximately 7 km in depth, with a southwestward dip consistent with the host rocks, and shows strong structural control by two regional faults. Magnetometry revealed low magnetic susceptibility, indicating the absence of Fe/Mg-rich minerals, along with positive magnetic lineaments correlated with the faults, whereas gamma spectrometry highlighted signatures compatible with highly differentiated igneous rocks enriched in K, Th, and U, as well as thorium peaks consistent with facies containing allanite, thus allowing the granite body to be distinguished from adjacent lithologies. The results indicate an intrusion with compositional characteristics compatible with an S-type, syn-collisional granite, formed by crustal melting of metasedimentary rocks, showing strong deformation, aluminous mineral assemblages, absence of ferromagnesian minerals, and the presence of mica schist and amphibolite xenoliths, contrasting with the features expected for an alkaline granite. However, due to the absence of geochemical analyses in this study, which would be necessary to confirm this interpretation, and the reliance on limited previous data, the body is herein maintained as an A-type granite associated with an aluminous affinity