Phanerozoic geological evolution of the Equatorial Atlantic domain

Abstract

The Phanerozoic geological evolution of the Equatorial Atlantic domain has been controlled since the end of Early Cretaceous by the Romanche and Saint Paul transform faults. These faults did not follow the PanAfrican shear zones, but were surimposed on Palaeozoic basins. From Neocomian to Barremian, the Central Atlantic rift propagated southward in Cassiporé and Marajó basins, and the South Atlantic rift propagated northward in Potiguar and Benue basins. During Aptian times, the Equatorial Atlantic transform domain appeared as a transfer zone between the northward propagating tip of South Atlantic and the Central Atlantic. Between the transform faults, oceanic accretion started during Late Aptian in small divergent segments, from south to north: Benin-Mundaú, deep Ivorian basin-Barreirinhas, Liberia-Cassiporé. From Late Aptian to Late Albian, the Togo-Ghana-Ceará basins appeared along the Romanche transform fault, and Côte dÍvoire-Parà-Maranhão basins along Saint Paul transform fault. They were rapidly subsiding in intra-continental settings. During Late Cretaceous, these basins became active transform continental margins, and passive margins since Santonian times. In the same time, the continental edge uplifted leading either to important erosion on the shelf or to marginal ridges parallel to the transform faults in deeper settings

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

“…1). The current views on the opening of the equatorial Atlantic Ocean are summarized as follows (e.g., Popoff, 1988;MacGregor et al, 2003;Basile et al, 2005;Brownfield and Charpentier, 2006). The synrift stage begins in the Neocomian by transcurrent and extensional faulting (Fig.…”

“…This transgression is documented farther inland in South America in at least two embayments, suggesting the persistence of a very low topography on that side of the equatorial Atlantic Ocean. Transform faults are still active as the mid-ocean ridges migrate along the Ivory Coast-Ghana marginal ridge, i.e., the "active transform margin" stage of Basile et al (2005). Anticlines form at the African tip of the Romanche and Saint Paul transform faults as a result of transpression.…”

“…The equatorial Atlantic Ocean opened as a consequence of oblique divergence along what were to become the best known examples of transform and oblique continental margins of northern South America and West Africa (Emery et al, 1975;Mascle and Blarez, 1987;Basile et al, 2005;Figs. 1 and 2).…”

“…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.…”

Fault evolution in the Potiguar rift termination, equatorial margin of Brazil

“…The equatorial margin of South America and West African is characterized by Mesozoic-Cenozoic basins formed along more than 2000 km along the South Atlantic (Matos, 2000). Rifting in the equatorial Atlantic margin occurred during the early Barremian to Aptian, and the first oceanic crust probably accreted during the late Aptian (Basile et al, 2005). This margin and the associated South Atlantic in the South American plate also encompass the Chain, Romanche, and Saint Paul transform faults, which are several hundreds of kilometers long (Fig.…”