Climate variability and ice-sheet dynamics during the last three glaciations

A composite North Atlantic record from DSDP Site 609 and IODP Site U1308 spans the past 300,000 years and shows that variability within the penultimate glaciation differed substantially from that of the surrounding two glaciations. Hematite-stained grains exhibit similar repetitive down-core variati...

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Bibliographic Details
Published in:Earth and Planetary Science Letters
Main Authors: Obrochta, Stephen P., Crowley, Thomas J., Channell, James E. T., Hodell, David A., Baker, Paul A., Seki, Arisa, Yokoyama, Yusuke
Format: Article in Journal/Newspaper
Language:English
Published: 2014
Subjects:
01 - Climate Change and Earth-Ocean Atmosphere Systems
Antarctic
Hudson
Hudson Strait
Antarc*
Ice Sheet
Iceberg*
North Atlantic
Sea ice
Online Access:http://eprints.esc.cam.ac.uk/3233/
http://eprints.esc.cam.ac.uk/3233/1/Obrochta%20et%20al.%20-%202014%20-%20Climate%20variability%20and%20ice-sheet%20dynamics%20during.pdf
http://eprints.esc.cam.ac.uk/3233/2/1-s2.0-S0012821X14005494-gr001.jpg
http://eprints.esc.cam.ac.uk/3233/3/mmc1.pdf
http://eprints.esc.cam.ac.uk/3233/4/mmc2.kml
http://www.sciencedirect.com/science/article/pii/S0012821X14005494
https://doi.org/10.1016/j.epsl.2014.09.004
Description
Summary:A composite North Atlantic record from DSDP Site 609 and IODP Site U1308 spans the past 300,000 years and shows that variability within the penultimate glaciation differed substantially from that of the surrounding two glaciations. Hematite-stained grains exhibit similar repetitive down-core variations within the Marine Isotope Stage (MIS) 8 and 4–2 intervals, but little cyclic variability within the MIS 6 section. There is also no petrologic evidence, in terms of detrital carbonate-rich (Heinrich) layers, for surging of the Laurentide Ice Sheet through the Hudson Strait during MIS 6. Rather, very high background concentration of iceberg-rafted debris (IRD) indicates near continuous glacial meltwater input that likely increased thermohaline disruption sensitivity to relatively weak forcing events, such as expanded sea ice over deepwater formation sites. Altered (sub)tropical precipitation patterns and Antarctic warming during high orbital precession and low 65°N summer insolation appear related to high abundance of Icelandic glass shards and southward sea ice expansion. Differing European and North American ice sheet configurations, perhaps aided by larger variations in eccentricity leading to cooler summers, may have contributed to the relative stability of the Laurentide Ice Sheet in the Hudson Strait region during MIS 6.

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