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

Type Article
Date 2014-11-15
Language English
Author(s) Obrochta Stephen P.1, Crowley Thomas J.2, Channell James E. T.3, Hodell David A.4, Baker Paul A.5, Seki Arisa1, Yokoyama Yusuke1
Affiliation(s) 1 : Univ Tokyo, Atmosphere & Ocean Res Inst, Tokyo 2778564, Japan.
2 : Braeheads Inst, Glasgow EH40 3DH, Lanark, Scotland.
3 : Univ Florida, Dept Geol Sci, Gainesville, FL 32611 USA.
4 : Univ Cambridge, Dept Earth Sci, Cambridge CB2 3EQ, England.
5 : Duke Univ, Div Earth & Ocean Sci, Durham, NC 27708 USA.
Source Earth And Planetary Science Letters (0012-821X) (Elsevier Science Bv), 2014-11-15 , Vol. 406 , P. 198-212
DOI 10.1016/j.epsl.2014.09.004
WOS© Times Cited 46
Keyword(s) insolation, IRD, Heinrich Event, MIS 6, MIS 8, AMOC
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 degrees 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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