Radiolaria distribution in Middle and Late Quaternary sediments and paleoceanography in the eastern Angola Basin
Bjørklund, K.R.; Jansen, J.H.F. (1984). Radiolaria distribution in Middle and Late Quaternary sediments and paleoceanography in the eastern Angola Basin. Neth. J. Sea Res. 17(2-4): 299-312
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
|  |
| Authors | | Top |
- Bjørklund, K.R.
- Jansen, J.H.F.
|
|
|
| Abstract |
The established Radiolaria biozonation from other tropical oceans could not be recognized in the 4 cores studied. However, Radiolaria maxima and minima abundances correlate with maxima and minima of the total calcium carbonate. The glacial occurrence of Cycladophora davisiana in the Angola Basin cores reaches values similar to those at the upper continental slope off Namibia. Relative counts of C. davisiana suggest that this species reflects coastal and oceanic upwelling in both space and time in the equatorial Atlantic Ocean. Opal refractive-index values indicate a more intensive opal alternation in cores with low sedimentation rates, due to a longer residence time of the opal microfossils at the water-sediment interface. There is no apparent correlation between this index and the number of Radiolaria in the sediment. The diatom Ethmodiscus rex is present not only in glacial carbonate minima but also in some interglacial carbonate maxima. They reflect strong opal dissolution rather than high fertility of the surface water. |
|
