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40Ar/39Ar hornblende provenance clues about Heinrich event 3 (H3)

By
Greg E. Downing
Greg E. Downing
1
Department of Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, USA
2
Present address: 4916 Harriet Avenue S., Minneapolis, MN 55419, USA
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Sidney R. Hemming
Sidney R. Hemming
1
Department of Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, USA
3
Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, USA
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Anne Jost
Anne Jost
1
Department of Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, USA
4
Present address: UPMC Université Paris 06, UMR 7619, Sisyphe, F-75005, Paris, France and CNRS, UMR 7619, Sisyphe, F-75005, Paris, France
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Martin Roy
Martin Roy
5
Département. des Sciences de la Terre et de l'Atmosphère/GEOTOP, Université du Québec à Montréal, C.P. 8888, Succ. Centreville, Montréal, Quebec, Canada H3C 3P8
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Published:
January 01, 2014

Abstract

Iceberg discharges into the North Atlantic are important sources of fresh water, and the sediments they deposit can provide constraints on which sectors of different ice sheets were contributing icebergs. 40Ar/39Ar ages of sand-sized hornblende grains provide useful constraints on IRD (ice-rafted detritus) source areas.

Heinrich events are intervals of anomalously high percentages of IRD in marine sediment cores of the North Atlantic IRD belt. In contrast to the others, Heinrich event 3 (H3) records a significantly lower flux of IRD. This study compares 40Ar/39Ar hornblende age distributions from the interval around and including H3 in giant gravity core EW9303-GGC31 from Orphan Knoll, in the southern part of the Labrador Sea, with piston core V28-82 in the eastern part of the North Atlantic IRD belt. Collectively, these results confirm that H3 represents a Hudson Strait IRD event, but that it was smaller than during H1, H2, H4 and H5, and therefore comprises only a small fraction of the detritus at the eastern North Atlantic location of V28-82. These results support a previously published interpretation of across-strait ice flow during H3 at Hudson Strait.

Supplementary material:

Appendix 1 is 40Ar/39Ar data from core EW9303-GGC31; Appendix 2 is grain counts across H3 from core V28-82; Appendix 3 is 40Ar/39Ar data from core V28-82; these are available at http://www.geolsoc.org.uk/SUP18631.

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Contents

Geological Society, London, Special Publications

Advances in 40Ar/39Ar Dating: From Archaeology to Planetary Sciences

F. Jourdan
F. Jourdan
Curtin University, Australia
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D. F. Mark
D. F. Mark
Scottish Universities Environmental Research Centre, UK
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C. Verati
C. Verati
University of Nice, France
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Geological Society of London
Volume
378
ISBN electronic:
9781862396623
Publication date:
January 01, 2014

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