Relationships between shearing and granitic magma emplacement: The Remígio-Pocinhos shear zone in the São José do campestre massif, NE Brazil

Abstract

Based on mineralogical, geochemical and textural characteristics, a variety of granite types was identified amongst the intrusions emplaced during the tectonic activity along the Remígio-Pocinhos shear zone in NE Brazil during the latest stages of the Brasiliano orogeny. They include peraluminous granites with I-type mineralogical compositions as well as transitional-to- alkaline geochemical characteristics. These granites contain mafic to intermediate microgranular enclaves. Overall, they are very similar to many other Brasiliano-age plutons in the extreme NE of Brazil. Metaluminous alkaline granites with aegirine-augite usually contain andradite as a minor phase, and titanite as an important accessory mineral. Several aspects of their trace element geochemistry repeat features of syn to late-tectonic alkaline granites in other parts of NE Brazil and in the rest of the world. The shear zone has deep roots, and the heat flow during granite genesis was probably high. A variety of lower crustal source rocks was probably involved in the genesis of these granites.