Early Oligocene stratigraphic turnover on the west Africa continental margin: a signature of the Tertiary greenhouse-to-icehouse transition?
Article first published online: 21 APR 2002
Blackwell Science Ltd
Volume 11, Issue 4, pages 135–140, August 1999
How to Cite
Séranne (1999), Early Oligocene stratigraphic turnover on the west Africa continental margin: a signature of the Tertiary greenhouse-to-icehouse transition?. Terra Nova, 11: 135–140. doi: 10.1046/j.1365-3121.1999.00246.x
- Issue published online: 21 APR 2002
- Article first published online: 21 APR 2002
The post-rift stratigraphy on the west African margin is characterized by aggradation of a carbonate ramp during Late Cretaceous to Eocene epochs and progradation of a terrigenous wedge from Oligocene to the Present. Such first-order structure has been attributed in the past to geodynamic forcing. However, comparison of the stratigraphic record of the margin with eustasy, δ18O and 87Sr/86Sr curves, shows a close temporal relationship with the Tertiary climate cooling, an increase of continental weathering, and a long-term lowering of sea level. We suggest that the transition from low-amplitude, high-frequency sea-level changes during the greenhouse period to high-amplitude, high-frequency sea-level changes during the icehouse period may account for: (i) the switch from an aggrading carbonate ramp to a prograding clastic wedge, and (ii) the enhanced continental weathering and increased terrigenous influx to the margin.