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The 103 meter Mt. Logan, Canada ice core was drilled with an electromechanical drill in 1980 from a site on a saddle
at 60 deg. 35 min. N, 140 deg. 35 min. W at an elevation of 5340 meters a.s.l.
Further pit sampling in 1981, 1986, 1988, and 2000 have stretched the core record to 2000.
Data has been collected on the stable isotopes of oxygen and allowed for an assesment of the
accumulation rate at the site. Annual increments have been determined by a number of methods.
Total B-activity variations, delta 18-O oscillations, nitrate concentration variations,
and in a few selected sections sodium ion concentration variations were used to count annual layers.
Below 50 meters, delta 18-O oscillations become obscured and the other annual indicators replaced the
use of isotope ratios. For more details on the delta 18-O time series and net acumulation time series
see the following references.
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Moore, G.W.K., G. Holdsworth, and K. Alverson, 2002,
Climate change in the North Pacific region over the past three centuries
Nature, 420, 6914, 401-403 (28 November 2002); doi:10.1038/nature01229
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Holdsworth, G., H.R. Krouse and M. Nosal, 1992,
Ice core climate signals from Mount Logan, Yukon A.D. 1700-1897, In:
Climate Since A.D. 1500. Raymond S. Bradley and Philip D. Jones (eds.).
Routledge. London and New York. pp. 483-504.
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Monaghan, M.C. and G. Holdsworth, 1990, The origin of non-sea-salt sulphate
in the Mount Logan ice core, Nature 343:245-248.
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Holdsworth, G., H.R. Krouse, and E. Peake, 1988,
Trace-acid ion content of shallow snow and ice cores from mountain sites
in western Canada, Annals of Glaciology 10:57-62.
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Mount Logan isotope and accumulation data
Mount Logan glaciochemical data, Text
or Excel
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The 186 m-long Mt. Logan PR Col ice core was
drilled to bedrock by the Geological Survey of Canada
(GSC) during the summers of 2001 and 2002 in a relatively
flat area with low ice velocities (<0.2 m a-1)
[Fisher et al., 2004].
The mean accumulation rate at the site is 0.41 m a-1 (water).
The concentrations of major ions (e.g. Na+, Cl-,
SO4-) and
trace elements (e.g. Pb, Al, Fe, Sr, Cs, U, REEs) were
measured on a total of 6900 pristine meltwater samples by
ion chromatography and inductively coupled plasma mass
spectrometry. The resulting 8000 year-long record
has sub-annual resolution (4-30 samples/year) from 1700-1998 AD,
and annual to multi-decadal resolution from 8000 BP to 1700 AD.
References:
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Osterberg, E., P. Mayewski, K. Kreutz, D. Fisher, M. Handley, S. Sneed,
C. Zdanowicz, J. Zheng, M. Demuth, M. Waskiewicz, and J. Bourgeois. 2008.
Ice core record of rising lead pollution in the North Pacific atmosphere.
Geophys. Res. Lett., 35, L05810, doi:10.1029/2007GL032680.
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Fisher, D., et al. (2004), Stable isotope records from Mt. Logan, Eclipse ice
cores and nearby Jellybean Lake. Water cycle of the North Pacific over
2000 years and over five vertical kilometers: Sudden shifts and tropical
connections, Geogr. Phys. Quat., 58, 337-352.
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