The tectonic significance of the Cabo Frio Tectonic Domain in the SE Brazilian margin: a Paleoproterozoic through Cretaceous saga of a reworked continental margin

Renata Da Silva Schmitt,Richard Armstrong,Rudolph Trouw,Natasha S Gomes Stanton,William Randall Van Schmus

doi:10.1590/2317-4889201620150025

Abstract

ABSTRACT: The Cabo Frio Tectonic Domain is composed of a Paleoproterozoic basement tectonically interleaved with Neoproterozoic supracrustal rocks (Buzios-Palmital successions). It is in contact with the Neoproterozoic-Cambrian Ribeira Orogen along the SE Brazilian coast. The basement was part of at least three continental margins: (a) 1.97 Ga; (b) 0.59 - 0.53 Ga; (c) 0.14 Ga to today. It consists of continental magmatic arc rocks of 1.99 to 1.94 Ga. Zircon cores show a 2.5 - 2.6 Ga inheritance from the ancient margin of the Congo Craton. During the Ediacaran, this domain was thinned and intruded by tholeiitic mafic dykes during the development of an oceanic basin at ca. 0.59 Ma. After the tectonic inversion, these basin deposits reached high P-T metamorphic conditions, by subduction of the oceanic lithosphere, and were later exhumed as nappes over the basement. The Cabo Frio Tectonic Domain collided with the arc domain of the Ribeira Orogen at ca. 0.54 Ga. It is not an exotic block, but the eastern transition between this orogen and the Congo Craton. Almost 400 m.y. later, the South Atlantic rift zone followed roughly this suture, not coincidently. It shows how the Cabo Frio Tectonic Domain was reactivated as a continental margin in successive extensional and convergent events through geological time.

Highlights

The tectonic reactivation of ancient sutures between lithospheric domains is recorded through geological time (Buiter & Torsvik 2014)
We present the hypothesis that this domain was repeatedly part of a continental margin recycled in successive divergent/convergent settings, along reworked sutures, and that there is nothing exotic about it
The Cabo Frio Tectonic Domain (CFTD) is today partially exposed on the Brazilian Continental margin

Summary

INTRODUCTION

The tectonic reactivation of ancient sutures between lithospheric domains is recorded through geological time (Buiter & Torsvik 2014). The Cabo Frio Tectonic Domain (CFTD) corresponds to a region on the coast of Rio de Janeiro State (Brazil) that contains atypical geological features in comparison to the adjacent units of the Brazilian continental margin (Fig. 1) Considering this and since it is largely covered by post-Jurassic sedimentary/volcanic deposits, it has been regarded by several authors as an exotic terrane (Rosier 1957, 1965; Fonseca et al 2012; Campos Neto 2000; Heilbron et al 2000, 2008; Schmitt et al 2008b; Brito Neves et al 2014). U-Pb zircon – TIMS – Upper intercept U-Pb zircon SHRIMP 9,10 Rb-Sr whole rock

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Findings

DISCUSSION