Oligocene to Holocene sediment drifts and bottom currents on the slope of Gabon continental margin (west Africa)
In: Sedimentary Geology. Elsevier: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0037-0738; e-ISSN 1879-0968, more
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| Keywords |
Geological time > Phanerozoic > Geological time > Cenozoic > Paleogene > Palaeogene > Oligocene
Geological time > Phanerozoic > Geological time > Cenozoic > Tertiary > Cenozoic > Neogene
Sediments > Clastics > Contourites
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| Author keywords |
west Africa margin; southeast Atlantic; drifts; slope deposits |
| Authors | | Top |
- Séranne, M
- Nzé Abeigne, C.-R.
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| Abstract |
Seismic reflection profiles on the slope of the south Gabon continental margin display furrows 2 km wide and some 200 m deep, that develop normal to the margin in 500–1500 m water depth. Furrows are characterised by an aggradation/progradation pattern which leads to margin-parallel, northwestward migration of their axes through time. These structures, previously interpreted as turbidity current channels, display the distinctive seismic image and internal organisation of sediment drifts, constructed by the activity of bottom currents. Sediment drifts were initiated above a major Oligocene unconformity, and they developed within a Oligocene to Present megasequence of general progradation of the margin, whilst they are markedly absent from the underlying Late Cretaceous–Eocene aggradation megasequence. The presence of upslope migrating sediment waves, and the northwest migration of the sediment drifts indicate deposition by bottom current flowing upslope, under the influence of the Coriolis force. Such landwards-directed bottom currents on the slope probably represent coastal upwelling, which has been active along the west Africa margin throughout the Neogene. |
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