Mesozoic Biostratigraphic, Paleoenvironmental, and Paleobiogeographic Synthesis, Equatorial Atlantic
Cretaceous sediments from Ocean Drilling Program Leg 159 on the Côte d’Ivoire-Ghana Marginal Ridge (CIGMR), eastern equatorial Atlantic, are characterized by distinct stratigraphic changes in sedimentary facies associated with changes in the composition of the clayey and organic fractions, as well as of the calcareous nannofossil, radiolarian, foraminiferal, and palynomorph assemblages. In the absence of reliable magnetostratigraphic information, an integrated biostratigraphy provides the only means used to calibrate the geologic history of the Leg 159 area.
The existence of marine depositional environments as early as the late Aptian to early Albian close to the Leg 159 drill sites puts constraints on the timing of the opening of the equatorial Atlantic gateway. Marine sedimentation on the ridge suggests that the West African and South American cratons were largely detached at this segment of the margin by the middle to late Albian. During the Cenomanian to Coniacian the ridge appears to have remained in an elevated position with concurrent low deposition or condensation (Site 959), high carbonate debris accumulation (Site 960), and even erosion (Site 962). Total organic Carbon measurements and microfaunal data lead us to suggest that, following the early opening of the seaway during the Albian, circulation remained restricted in the fragmented sub-basins of the CIGMR. It probably was not until the Santonian that a deep-water connection and circulation system became established between the Central and the South Atlantic. The sedimentary and faunal record at Site 959 show that a rapid subsidence occurred during the Santonian, with sub-calcite compensation depth conditions maintained until and beyond the Cretaceous/Tertiary boundary.
M. R. Moullade and D. K. Watkins and F. Oboh-Ikuenobe and J. P. Bellier and E. Masure and A. E. Holbourn and J. Erbacher and W. Kuhnt and T. K. Pletsch and M. A. Kaminski and R. Rauscher and S. Shafik and O. Yepes and J. Dejax and J. M. Gregg and I. Shin and M. Schuler, "Mesozoic Biostratigraphic, Paleoenvironmental, and Paleobiogeographic Synthesis, Equatorial Atlantic," Proceedings of the Ocean Drilling Program: Scientific Results, vol. 159, pp. 481-490, Texas A&M University, Dec 1998.
The definitive version is available at http://dx.doi.org/10.2973/odp.proc.sr.159.049.1998
Geosciences and Geological and Petroleum Engineering
Keywords and Phrases
Biostratigraphy; Mesozoic; Paleobiogeography; Paleoenvironment
International Standard Serial Number (ISSN)
Book - Chapter
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