Deformation and chronology of the granitic magmatism associated with the Tauá and Senador Pompeu shear zones (Borborema Province, NE, Brazil)

Abstract

Amongst the most significant tectonic features of the Borborema Province (NE Brazil) are the widespread transcurrent shear systems and expressive granitic magmatism. The chronological record between the magmatism and deformation mechanisms is only locally known. In the state of Ceará two regional scale shear zones, Senador Pompeu and Tauá, deform the crystalline basement and give rise, in the tractional sites, to emplacement of plutons and dyke swarms, as well as late-stage molassic sedimentary basins basins. Granitic plutons and dyke swarms would have been emplaced in the tractional sites of such system, along with the formation of late-orogenic sedimentary basins. However, there is not sufficient structural and geochronological data for an accurate demonstration of how magmatism and deformation are related. Furthermore, the deformation mechanisms are still poorly known. These mechanisms encompass ductile to brittle-ductile conditions as a result of exhumation of the province. In this project, we intend to investigate the connection between magmatism and the deformation mechanisms involved in the ductile to brittle-ductile transition. We will use dykes and ring intrusive of the Tauá shear zone, as well as the fault systems that limit the Cococi basin in the merge of the Tauá-Senador Pompeu shear zones, as reference for the study. This result will allow estimation of the chronology of the events and of parameters consistent with the pressure, temperature and strain rate conditions that shaped the province in the Neoproterozoic. (AU)