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Early Oligocene stratigraphic turnover on the west Africa continental margin: a signature of the Tertiary greenhouse‐to‐icehouse transition?
Author(s) -
Seranne
Publication year - 1999
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1046/j.1365-3121.1999.00246.x
Subject(s) - geology , terrigenous sediment , progradation , paleontology , passive margin , continental margin , paleogene , sea level , clastic rock , orbital forcing , neogene , rift , cretaceous , geomorphology , oceanography , sedimentary rock , tectonics , glacial period , facies , structural basin
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, δ 18 O and 87 Sr/ 86 Sr 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.