Intraplate Strike-Slip Corridor within South America (NE Border of the Paraná Basin) Unveiled by Structural Analysis of Faults and Fracture Swarms

Paola Cianfarra,Marcos Roberto Pinheiro,Francesco Salvini,Fernando Nadal Junqueira Villela

doi:10.3390/geosciences12020101

Paola Cianfarra, Marcos Roberto Pinheiro + Show 2 more

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https://doi.org/10.3390/geosciences12020101

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Abstract

We present the effect of neotectonics in intracratonic settings as revealed by the surface, brittle deformation associated to a regionally-sized shear corridor, which affects Southeastern Brazil. The deformation zone is characterized by the presence of nearly orthogonal fracture sets, interpreted as systematic and non-systematic joints often cutting Quaternary deposits. An original methodology of fault and joint inversion by the Monte Carlo converging approach is used to infer multiple paleostress fields. The method provides the best orientation of the principal paleo-stresses responsible for the observed fracturing. At each step of the inversion process, structures are uniquely associated to the stress tensor that provides the lowest error. The results showed the poly-phased tectonic history of the shear corridor studied and paleostresses compatible with a regional strike-slip motion. Specifically, an E-W, left-lateral shear was followed by an E-W, right-lateral kinematics related to the post-Paleogene drifting of South American Plate and its clockwise rotation. The latter tectonic event is presently responsible for brittle deformation observed in Quaternary deposits. The proposed deformation corridor may represent the Cenozoic reactivation of an ancient weakness zone. We speculate that the described intraplate strike-slip deformation belt represents the continental prosecution of the Rio de Janeiro fracture zone.

Highlights

The classical paradigm of plate tectonic theory assumes that deformation associated to plate interactions is concentrated into narrow belts along the plate margins and that the lithosphere in the plate interiors is, to a first approximation, rigid and relatively stable (Morgan [1]; Holdsworth et al [2]; Wilson et al [3])
The results from the present work allow addressing a series of issue regarding the Cenozoic tectonic evolution of the NE border of the Paraná basin in the framework of regional geodynamics
The first is characterized by NW-SE minimum horizontal stress and NE-SW maximum horizontal stress in a general extensional regime

Summary

Introduction

The classical paradigm of plate tectonic theory assumes that deformation associated to plate interactions is concentrated into narrow belts along the plate margins and that the lithosphere in the plate interiors is, to a first approximation, rigid and relatively stable (Morgan [1]; Holdsworth et al [2]; Wilson et al [3]). This is true for regions underlain by oceanic lithosphere. The reactivation of inherited crustal weakness shear zones relates to the intraplate response of the late, Paleozoic stages of Pangea amalgamation followed by its Mesozoic breakup, post-rift spreading and drifting (Torsvik et al [13]; Hasui [8])

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