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

Obrochta, Stephen P. and Crowley, Thomas J. and Channell, James E. T. and Hodell, David A. and Baker, Paul A. and Seki, Arisa and Yokoyama, Yusuke (2014) Climate variability and ice-sheet dynamics during the last three glaciations. Earth and Planetary Science Letters, 406. pp. 198-212. ISSN 0012821X DOI 10.1016/j.epsl.2014.09.004

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Abstract

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.

Item Type:	Article
Additional Information:	Data included in this manuscript are available at http://dx.doi.org/10.1594/PANGAEA.834640
Uncontrolled Keywords:	2014AREP; IA68;
Subjects:	01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions:	01 - Climate Change and Earth-Ocean Atmosphere Systems 07 - Gold Open Access
Journal or Publication Title:	Earth and Planetary Science Letters
Volume:	406
Page Range:	pp. 198-212
Identification Number:	10.1016/j.epsl.2014.09.004
Depositing User:	Sarah Humbert
Date Deposited:	06 Feb 2015 17:28
Last Modified:	16 Feb 2015 18:22
URI:	http://eprints.esc.cam.ac.uk/id/eprint/3233

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