Climate variability in the southern Benguela region during Marine Isotope Stage 11

Author(s): Dickson, A. J.; Leng, M. J.; Maslin, M. A.; Roehl, U.; Westerhold, T.
Author Affiliation(s): Primary:
University College London, London, United Kingdom
Other:
NERC Isotope Geoscience Laboratory, United Kingdom
University Bremen, Federal Republic of Germany
Volume Title: AGU 2006 fall meeting
Source: Eos, Transactions, American Geophysical Union, 87( Fall Meeting Suppl.); American Geophysical Union 2006 fall meeting, San Francisco, CA, Dec. 11-15, 2006. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0096-3941 CODEN: EOSTAJ
Note: In English
Summary: Marine Isotope Stage 11 (MIS-11) has been highlighted as a potential analogue for the present day Holocene interglacial because of a strong similarity in the pattern of orbital forcing. Enhanced warmth during MIS-11 has been attributed to a strong thermohaline circulation or high levels of atmospheric CO2. The Southern Benguela Region can offer insights into both of these hypotheses since it is influenced by both the Benguela Current and the boundary of seasonal coastal upwelling. ODP 1085B has been targeted to generate a sub- millennial scale resolution reconstruction of palaeoclimate variability during the period encompassing MIS-13 to MIS-9. Planktonic foraminiferal stable isotopes indicate that termination V occurred with an approximate sea surface warming of 4°C, and that sub-millennial scale variability during the peak of MIS-11 occurred with fluctuations in the δ18O of Neogloboquadrina pachyderma (d) of ≈0.5 per mil. On the basis of a long-term sedimentation rate of ≈8cm/kyrs, it is estimated that the MIS-11 interglacial in ODP 1085B lasted for approximately 26ka and can be broken down into two main intervals. In the first interval following termination V, Ca accumulation fell gradually, possibly reflecting a fall in surface water CaCO3 production. In the second interval, Ti/Al and Rb/Sr ratios increase suddenly, marking a dramatic increase in the deposition of terrigenous sediments and a possible deterioration of regional climate. A cooler second interval within MIS-11 may bear some resemblance to neo-glacial cooling during the Holocene, but the lack of accurate dating makes such comparisons difficult at present.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Africa; Atlantic Ocean; Benguela Current; Cape Basin; Carbon dioxide; Cenozoic; Coastal environment; Foraminifera; Geochemistry; Holocene; Invertebrates; Isotope ratios; Isotopes; Leg 175; MIS 11; Marine environment; Microfossils; Middle Pleistocene; O-18/O-16; ODP Site 1085; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleoclimatology; Paleocurrents; Pleistocene; Protists; Quaternary; South Atlantic; Stable isotopes; Thermohaline circulation; Upwelling
Coordinates: S292228 S292228 E0135924 E0135924
Record ID: 2007059155
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