1887

oa South African Journal of Geology - Preliminary findings of the IMAGES-II programme (International MArine Global changE Study) using giant piston cores of Late Quaternary marine sediments from the continental slope and rise off southern Africa

Volume 102 Number 4
  • ISSN : 1012-0750
  • E-ISSN: 1996-8590

 

Abstract

The second cruise of the new French research vessel, the Marion Dufresne, was also the second cruise of the IMAGES-II Programme, the aim of which was to explore the history of the Indian Ocean-Atlantic Ocean connection and of the southeastern Atlantic upwelling region over the last 300 000 years in the Late Quaternary. To this end, 24 giant piston cores, with an average length of 32 m, were recovered from the ocean basins and the continental slope and rise off southern Africa, between Durban (South Africa) and Lobito (Angola). The cores off the east coast of South Africa were predominantly foraminiferal and coccolith oozes with thin quartzose turbidites at intervals. Off the west coast of South Africa, the predominant lithology was the same, but turbidites were absent and the amounts of organic matter increased equatorwards toward the main upwelling cell of the Benguela ecosystem off southern Namibia. The imprint of upwelling was most clearly seen off Namibia in the abundance of organic matter, the presence of hydrogen sulphide, and the preservation of diatoms. Sea-level fluctuations led to seaward excursions of the upwelling cell during lowstands (glacials), when abundant organic matter was deposited on the slope and rise and landward shifts during highstands (interglacials like those of today), when the upwelling zone moved back onto the shelf. North of the Walvis Ridge, the Kunene and Angola margin is dominated by organic- and diatom-rich terrigenous muds, very distinct from the carbonate-dominated oozes off Namibia and South Africa.

Loading full text...

Full text loading...

Loading

Article metrics loading...

/content/journal/10520/EJC-942d783ec
1999-12-01
2020-09-25

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error