Post-rift stratigraphic architectures along the African margin of the Equatorial Atlantic: Part I the influence of extension obliquity - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Tectonophysics Year : 2019

Post-rift stratigraphic architectures along the African margin of the Equatorial Atlantic: Part I the influence of extension obliquity

Abstract

We investigated the variability of the first-order crustal structure and early post-rift stratigraphy of six segments of the African Equatorial Atlantic margin using sub-surface data (seismic and wells). Extension obliquity of the segments varies from 0° for the West Ivory Coast and Ghana transform segments to 30° for the Togo-Benin oblique segment and 75° for the East Ivory Coast normally divergent segment. The Sierra Leone and Liberia segments underwent probably deformation during both the early Jurassic rifting of the Central Atlantic and the early Cretaceous rifting of the Equatorial Atlantic with contrasted divergence obliquities. For segments that underwent a single rifting, we show that, the higher the obliquity, the wider the crustal thinning domain. This has a major influence on the first-order geometry of all the post-rift horizons, including the present-day slope: the lower the obliquity, the larger the differential subsidence across the margin and the steeper the present-day slopes of post-rift horizons. This also has a major influence on the flexural isostatic response of the lithosphere to thermal- and erosion/sedimentation- driven (un)loads during the early post-rift. Narrow (transform) segments underwent higher flexural (and/or thermal) uplifts in the proximal domain than wider divergent segments. Along the same margin, divergent segments therefore may preserve early post-rift deposits in their proximal domains, whereas they are not preserved on nearby transform segments.
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insu-01982828 , version 1 (16-01-2019)

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Jing Ye, Delphine Rouby, Dominique Chardon, Massimo Dall'Asta, François Guillocheau, et al.. Post-rift stratigraphic architectures along the African margin of the Equatorial Atlantic: Part I the influence of extension obliquity. Tectonophysics, 2019, 753, pp.49-62. ⟨10.1016/j.tecto.2019.01.003⟩. ⟨insu-01982828⟩
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