Contribution to petrography, geochemistry and isotopic geology of the Itapuranga Granite in the central portion of the Brasília Belt

The Itapuranga granite is located in the central part of the Brasília Belt. It exhibits an elongated shape in the E-W di-rection and is associated with the Pyrenees Lineament. It presents porphyritic texture in different stages of deformation (protomylonite to ultramylonite), with mineralogy formed by K-feldspar phenocrysts in quartzo-feldspathic matrix, associated with biotite and amphibole, as well as titanite, epidote and zircon as accessory minerals. The geochemical data show high-K (shoshonitic) and metaluminous sub-alkaline composition, ranging from quartz syenite to syenogranite and monzogranite. The Sm-Nd T_DM model ages range from 1.27 to 1.91 Ga with values εNd (0) = -11 to -15, suggesting an older crustal source (Paleo- to Mesoproterozoic). This magmatism has a type-I geochemical signature and involves a fractionation process, probably from late-orogenic to post-collisional environment. The data obtained indicate that the Itapuranga Granite was originated from the partial fusion of a Paleoproterozoic crust, interacting with heterogeneous lithospheric mantle metassomatized during the subduction process. For these interpretations, there is an important contribution of asthenospheric sources linked to the collision of the Goiás Magmatic Arc is associated with the merger of the mantle by adiabatic decompression. (author)