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 amongstthe intrusions emplaced during the tectonic activity along the Remígio-Pocinhos shear zone in NE Brazil during the lateststages of the Brasiliano orogeny. They include peraluminous granites with I-type mineralogical compositions as well astransitional-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 alkalinegranites 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 ofNE Brazil and in the rest of the world. The shear zone has deep roots, and the heat flow during granite genesis was probablyhigh. A variety of lower crustal source rocks was probably involved in the genesis of these granites.

Keywords

• Seridó region
• Shear zones
• Emplacement of granite magmas
• Diversity of granite types
• Transitional granite types