Rift brittle deformation of SE-Brazilian continental margin: Kinematic analysis of onshore structures relative to the transfer and accommodation zones of southern Campos Basin. (January 2017)

• Record Type: Journal Article
• Authors: Savastano, Vítor Lamy Mesiano; Schmitt, Renata da Silva; Araújo, Mário Neto Cavalcanti de; Inocêncio, Leonardo Campos
• Is Part Of: Journal of structural geology. Volume 94(2017:Jan.)
• Page Start: 136
• Page End: 153
• Publication Date: 2017-01
• Subjects: Campos basin -- Accommodation zone -- Transfer zone -- Rift stage -- UAV geological mapping; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2016.11.012
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: High-resolution drone-supported mapping and traditional field work were used to refine the hierarchy and kinematics of rift-related faults in the basement rocks and Early Cretaceous mafic dikes onshore of the Campos Basin, SE-Brazil. Two sets of structures were identified. The most significant fault set is NE-SW oriented with predominantly normal displacement. At mesoscale, this fault set is arranged in a rhombic pattern, interpreted here as a breached relay ramp system. The rhombic pattern is a penetrative fabric from the thin-section to regional scale. The second-order set of structures is an E-W/ESE-WNW system of normal faults with sinistral component. These E-W structures are oriented parallel with regional intrabasinal transfer zones associated with the earliest stages of Campos Basin's rift system. The crosscutting relationship between the two fault sets and tholeiitic dikes implies that the NE-SW fault set is the older feature, but remained active until the final stages of rifting in this region as the second-order fault set is older than the tholeiitic dikes. Paleostresses estimated from fault slip inversion method indicated that extension was originally NW-SE, with formation of the E-W transfer, followed by ESE-WNW oblique opening associated with a relay ramp system and related accommodation zones. Highlights: E-W transference zones controlled South Atlantic early rift stage NW-SE extension. The accommodation zones are characterized by breached relay ramps of NE-SW faults. NE-SW brittle structures display a penetrative rhombic pattern, micro to regional. Tholeiitic dykes from Upper Cretaceous are syntectonic to the NE-SW system.