Seismic stratigraphy of Cretaceous eastern Central Atlantic Ocean: Basin evolution and palaeoceanographic implications
Résumé
The evolution and resulting morphology of a Cretaceous contourite drift in the eastern Central Atlantic oceanic basin is investigated in unprecedented detail using seismic imaging and age-calibrated cross-margin sections. The margin, from the shelf, slope to deep-water and abyssal plain is constructed by a succession of erosive and depositional mounded structures that relate to bottom-water currents and sediment winnowing. The regional mapping of these drifts, sediment waves and gravitational sedimentary systems allows us to test the Upper Cretaceous paleocirculation model. Combined with flexural backstripping of the regional cross section, it reveals the water-depth range at which the observed sedimentary features occur. A possible late Albian to Turonian contourite drift system is observed from Guinea to Mauritania. The development of a shallow to deep oceanic circulation system is a key element in the rock record, with implications for the palaeoceanography and layering of the Cretaceous ocean. The Cretaceous geological interval and oceanic model mirrors the stratification of the modern ocean and the morphology of its seafloor from offshore Morocco to Guinea.
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