R脙脙脙脙sultats pr脙脙脙脙liminaires sur la s脙脙脙脙dimentation p脙脙脙脙lagique de l'Atlantique tropical au Cr脙脙脙脙tac脙脙脙脙 et au Tertiaire (plateau de Demerara, Leg ODP 207)
- 作者：Danelian ; Taniel ; Le Callonnec ; Laurence ; Erbacher ; Jochen ; Mosher ; David C. ; Malone ; Mitchell J. ; et. al.
- 关键词：Tropical Atlantic ; Demerara ; Cretaceous ; Tertiary ; Black shales
- 刊名：Comptes rendus - Geoscience
- 出版年：2005
- 期刊代码：87_16310713
- 类别：ear
- 出版时间：April, 2005
- 卷：337
- 期：6
- 页码：609-616
- 文件大小：198 K
摘要
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. To cite this article: T. Danelian et al., C. R. Geoscience 337 (2005).