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The Mt Logan Holocene—late Wisconsinan isotope record: tropical Pacific—Yukon connections

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada, david.fisher{at}nrcan.gc.ca

Erich Osterberg

Climate Change Institute and Department of Earth Sciences, University of Maine, Orono ME 04469, USA

Art Dyke

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Dorthe Dahl-Jensen

Niels Bohr Institute, Juliane Maries Vej 30, University of Copenhagen, DK-2100, Copenhagen East, Denmark

Mike Demuth

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Christian Zdanowicz

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Jocelyne Bourgeois

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Roy M. Koerner

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Paul Mayewski

Climate Change Institute and Department of Earth Sciences, University of Maine, Orono ME 04469, USA

Cameron Wake

Climate Change Research Center, EOS, Morse Hall, University of New Hampshire, Durham NH 03824, USA

Karl Kreutz

Climate Change Institute and Department of Earth Sciences, University of Maine, Orono ME 04469, USA

Eric Steig

Quaternary Research Center, ESS, 19 Johnson Hall, Box 1360, University of Washington, Seattle WA 98195-1360, USA

James Zheng

Geological Survey of Canada, (NRCan), 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada

Kaplan Yalcin

Department of Geosciences, 102D Wilkinson Hall, Oregon State University, Corvallis OR 97331-5506, USA

Kumiko Goto-Azuma

NIPR, Kaga 1-9-10, Itabashi-ku, National Institute of Polar Research, Tokyo 173-8515, Japan

Brian Luckman

Department of Geography, University of Western Ontario, London, Ontario N6F 5C2, Canada

Summer Rupper

Department of Geological Sciences, Brigham Young University, S389, Provo UT 84602, USA

The ice core recovered from Prospector Russell Col on Mt Logan (5.4 km a.s.l.), in the Yukon spans over 20 000 years. This unique record offers a Pacific view of the stable isotope and chemical record from the Lateglacial to the present. The timescale is based on seasonal counted years, the largest known volcanic acid signatures and the major shift in stable isotopes and chemistry at the end of the Younger Dryas. There are large and sustained changes in the stable isotopic record that are anti-correlated with marine and continental chemistry series. The oxygen-18 in this area is not a proxy for palaeotemperature but rather for source region. The last major isotope shift in AD 1840 in (¹⁸O) and chemistry is compared with the Quinn's ENSO record. During periods of more frequent La Niña (stronger tropical easterlies) there is more zonal flow of water vapour transport to the Pacific Northwest, (¹⁸O) values are larger and the deuterium excess d smaller. These periods coincide with periods of lower accumulation/precipitation in southern Yukon. The Holocene (¹⁸O) record indicates many large shifts between the meridional (strong El Niño) and zonal (La Niña). Comparison of the Logan isotopic record and the moisture/temperature-sensitive time series of peat bog inception dates for the Northwest shows a strong correlation (0.36) that points to high accumulation rates coincident with low (¹⁸O) and enhanced meridional flow. Major changes in the core at 4200 BP and 7000—8000 BP point to enhanced meridional flow, which coincide with big changes in the Pacific palaeorecords of the balance between El Niño and La Niña. 4200 BP seems to have inaugurated the `modern' ENSO world.

Key Words: Mt Logan • stable isotopes • Holocene • ENSO • peat • N Pacific • sudden change.

The Holocene, Vol. 18, No. 5, 667-677 (2008)
DOI: 10.1177/0959683608092236


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