Preliminary results on Cretaceous-Tertiary tropical Atlantic pelagic sedimentation (Demerara Rise, ODP Leg 207)


Danelian, T., Le Callonnec, L., Erbacher, J., Mosher, D.C., Malone, M.C., Berti, D., Bice, K.L., Bostock, H., Brumsack, H.E., Forster, A., Heidersdorf, F., Henderiks, J., Janecek, T.J., Junium, C., MacLeod, K., Meyers, P.A., Mutterlose, J.H., Nishi, H., Norris, R.D., Ogg, J.G., O'Regan, M.A., Rea, B., Sexton, P., Sturt-Fredericks, H., Suganuma, Y., Thurow, J.W., Wilson, P.A., Wise, S.W. and Glatz, C. (2005) Preliminary results on Cretaceous-Tertiary tropical Atlantic pelagic sedimentation (Demerara Rise, ODP Leg 207). Comptes Rendus Geoscience, 337, (6), 609-616. (doi:10.1016/j.crte.2005.01.011).

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Description/Abstract

Five sites located on a bathymetric transect of the distal Demerara Rise were studied by ODP Leg 207. Albian sediments of essentially terrigenous nature (clay, siltstone, sandstone) are the oldest drilled stratigraphic levels and form apparently the top of the synrift sequence. They are overlain by Cenomanian to Santonian finely laminated black shales, rich in organic matter of marine origin, which accumulated on a thermally subsiding ramp. Early Campanian hiatuses are thought to be the result of final disjunction of Demerara Rise (South America) from Africa and the onset of deep water communication between the two Atlantic basins (south and central). The overlying Uppermost Cretaceous–Oligocene chalk includes rich and diversified calcareous plankton assemblages, as well as two radiolarian-rich intervals (Late Campanian and Middle Eocene). A complex erosional surface developed during the Late Oligocene–Early Miocene. Sedimentation was impeded since then on the intermediate and deep sites of Demerara Rise, possibly due to the action of deep submarine currents.

Item Type: Article
Additional Information: In French, English abstract
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Keywords: Tropical Atlantic, Demerara, Cretaceous, Tertiary, black shales
Subjects: Q Science > QE Geology
Divisions: University Structure - Pre August 2011 > School of Ocean & Earth Science (SOC/SOES)
ePrint ID: 23989
Date Deposited: 16 Mar 2006
Last Modified: 27 Mar 2014 18:13
URI: http://eprints.soton.ac.uk/id/eprint/23989

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