Meso-Cenozoic tectonic evolution of the SE Brazilian continental margin: Petrographic, kinematic and dynamic analysis of the onshore Araruama Lagoon Fault System. (September 2017)

• Record Type: Journal Article
• Authors: Souza, Pricilla Camões Martins de; Schmitt, Renata da Silva; Stanton, Natasha
• Is Part Of: Journal of structural geology. Volume 102(2017:Sep.)
• Page Start: 37
• Page End: 57
• Publication Date: 2017-09
• Subjects: Tectonic breccias -- Paleobreccias -- Superimposed slickenlines -- Tectonic reactivations -- Atlantic continental margin; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2017.07.003
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: The Ararauama Lagoon Fault System composes one of the most prominent set of lineaments of the SE Brazilian continental margin. It is located onshore in a key tectonic domain, where the basement inheritance rule is not followed. This fault system is characterized by ENE-WSW silicified tectonic breccias and cataclasites showing evidences of recurrent tectonic reactivations. Based on field work, microtectonic, kinematic and dynamic analysis, we reconstructed the paleostresses in the region and propose a sequence of three brittle deformational phases accountable for these reactivations: 1) NE-SW dextral transcurrence; 2) NNW-SSE dextral oblique extension that evolved to NNW-SSE "pure" extension; 3) ENE-WSW dextral oblique extension. These phases are reasonably correlated with the tectonic events responsible for the onset and evolution of the SE onshore rift basins, between the Neocretaceous and Holocene. However, based on petrographic studies and supported by regional geological correlations, we assume that the origin of this fault system is older, related to the Early Cretaceous South Atlantic rifting. This study provides significant information about one of the main structural trends of the SE Brazilian continental margin and the tectonic events that controlled its segmentation, since the Gondwana rifting, and compartmentalization of its onshore sedimentary deposits during the Cenozoic. Highlights: The ENE-WSW breccias might have been formed during the South Atlantic rifting. The basement inheritance rule is not followed in this part of the SE Brazilian margin. Evidences of three tectonic reactivations are registered in the ENE-WSW fault zones. The brittle deformational phases are coherent with the onshore rift basins' evolution.