Kinematics of the South Atlantic rift

Abstract

The South Atlantic rift basin evolved as branch of a large Jurassic-Cretaceous intraplate rift zone between the African and South American plates during the final breakup of western Gondwana. By quantitatively accounting for crustal deformation in the Central and West African rift zone, we indirectly construct the kinematic history of the pre-breakup evolution of the conjugate West African-Brazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic Pre-salt sag basin and the S\~ao Paulo High. We model an initial E-W directed extension between South America and Africa (fixed in present-day position) at very low extensional velocities until Upper Hauterivian times ($\approx$126 Ma) when rift activity along in the equatorial Atlantic domain started to increase significantly. During this initial $\approx$17 Myr-long stretching episode the Pre-salt basin width on the conjugate Brazilian and West African margins is generated. An intermediate stage between 126.57 Ma and Base Aptian is characterised by strain localisation, rapid lithospheric weakening in the equatorial Atlantic domain, resulting in both progressively increasing extensional velocities as well as a significant rotation of the extension direction to NE-SW. Final breakup between South America and Africa occurred in the conjugate Santos--Benguela margin segment at around 113 Ma and in the Equatorial Atlantic domain between the Ghanaian Ridge and the Piau\'i-Cear\'a margin at 103 Ma. We conclude that such a multi-velocity, multi-directional rift history exerts primary control on the evolution of this conjugate passive margins systems and can explain the first order tectonic structures along the South Atlantic and possibly other passive margins.Comment: 46 Pages, 22 figures. Submitted to Solid Earth (http://www.solid-earth.net). Abstract shortened due to arXiv restrictions. New version contains revisions and amendments as per reviewers requests. Supplementary data is available at http://datahub.io/en/dataset/southatlanticrif

Implications of structural inheritance in oblique rift zones for basin compartmentalization: Nkhata Basin, Malawi Rift (EARS)

“…Bartholomew et al, 1993;Erratt et al, 1999;Whipp et al, 2014) and passive margin rift systems are dissected by cross cutting faults, in a similar geometry observed in Malawi (Paton et al, 2008, Tsikalas et al, 2008Antobreh et al, 2009;Heine et al, 2013). Often these structures are not well defined as a consequence of poor quality data, wide spacing of available 2D lines, or a sub-salt setting.…”

Paleogeographic and structural evolution of northwestern Africa and its Atlantic margins since the early Mesozoic

“…Given their transform character, the margins of the equatorial Atlantic Ocean were mainly investigated through the kinematics of ocean opening (e.g., Basile et al, 2005;Moulin et al, 2009;Heine et al, 2013;Basile, 2015) with an emphasis on the fracture zones and the vertical movements induced along the margins (Bouillin et al, 1998;Clift et al, 1998;Bigot-Cormier et al, 2005;Mercier de Lépinay, 2016). The abruptness of the equatorial margins of Africa results from the strong control of strike-slip faults (i.e., future transforms) during rifting.…”

Speculative petroleum systems of the Punta del Este Basin (offshore Uruguay)

“…From a general point of view, four models for the genesis of these rift structures have been proposed: ■ the classical triple joint model as a consequence of a thermal anomaly (Introcaso & Ramos 1984, Stoakes et al 1991; ■ stress accommodation through rotation of the South American plate in relation to the African plate, as a result of crustal stretching north of the Walvis-Río Grande Rise and oceanic expansion to the south (Chang et al 1992); ■ oblique extension at the beginning of Atlantic Ocean expansion (MacDonald et al 2003); and ■ variations in strain orientation and stretching velocity (Heine et al 2013).…”

“…These structures were generated as a result of the suturing processes in Western Gondwana, which occurred at the end of the Proterozoic (Tankard et al 1995, Pángaro & Ramos 2012, Heine et al 2013.…”

“…The genesis of these basins was associated to the processes that led to the fragmentation of the Gondwana supercontinent and subsequent opening of the Atlantic Ocean, from the Jurassic onwards (Rabinowitz & LaBrecque 1979, Gladczenko et al 1997, Heine et al 2013.…”