Abstract
The Borborema Province (NE Brazil) has a long history of deformation, magmatism, and metamorphism during the Precambrian Eon. Thus, it represents a natural laboratory to investigate widely developed ductile-deformation markers, such as major fold belts and large-scale shear zones. This paper describes the structural evolution of a complex folded area of the Alto Moxoto Terrane, Central Borborema Province. In this region, para-derived rocks of the Sertânia Complex are intruded by orthogneisses and migmatitic orthogneisses. The Geophysical magnetometric expressions of the Borberma Province are characterized by strong aligned and folded magnetic lineaments and integrated structural analysis allowed us to identify three ductile deformation episodes. Brittle tectonics is also present, but not described. D1 stage represents the basement structural framework restricted to local structural windows of ancient orthogneisses and migmatites that are not mappable at the working scale. D2 deformation is widespread throughout the Central Borborema Province, producing nappes that mark top-to-NW tectonic vergence. Foliation and lineation attitudes are compatible with progressive deformation from tangential to strike-slip tectonics (i.e. D2 to D3). The latter is associated with the NE-SW Xinxo and Congo-Cruzeiro do Nordeste sinistral strike-slip shear zones, producing refold patterns that resemble Type-3 interference geometry. Based on airborne magnetic geophysical imaging interpretations and mesoscopic observations, we suggest that progressive deformation strongly affected the region and overprinted at large-scale early formed rocks.
Highlights
Lithospheric processes have played a major role in evolution of the Earth since early Archean times
We present a structural study focused on ductile deformation of the area surrounding Camalaú city in Paraíba State, covering a small area in the central part of the Alto Moxotó Terrane
The studied area is located in the central portion of the Alto Moxotó Terrane, which is part of a crustal fragment mosaic that is bounded by E-W regional scale shear zones marking major subdivision of the Central Subprovince (Santos and Medeiros 1999; Brito Neves et al 2000; Fig. 1b)
Summary
Lithospheric processes have played a major role in evolution of the Earth since early Archean times. The Borborema Province in NE Brazil represents a natural laboratory to investigate widely developed ductile-deformation markers, such as major fold belts and large-scale shear zones that are interpreted by some authors as remnants of continental sutures (Cordani et al 2013; Ganade de Araujo et al 2014; Santos et al 2015b). This province has a long history of deformation, magmatism and metamorphism spanning the Precambrian, originally defined by Almeida et al (1981).
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