Abstract
Summary Extensive investigations in the Madeira Abyssal Plain have revealed thick sequences of turbidites. Individual turbidites can be correlated over an area of 2° × 2°, and their emplacement can be shown to coincide with glacial onsets and terminations. The turbidites originate on the NW African margin and contain up to 2% organic carbon. They are virtually ungraded massive silts and clays, some with coarser basal layers. Seismic records through the abyssal plain show distinct changes in sediment character at a few hundred metres depth. Rates of accumulation are calculated from piston cores to be about 7.5 cm/1000 years, suggesting that the turbidites are a recent phenomenon. If the link with glacial onsets and terminations has held throughout, the first major turbidites may have been emplaced at 2.4 Ma, at the onset of Northern Hemisphere glaciation. Some turbidites may also have been emplaced during the supposed late Miocene glaciations. The Madeira Abyssal Plain is therefore a recent feature, and before its initiation the area would have had a ridge-flank type topography.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.