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Volcanic Ash Record in the Siple Dome Ice Core
N.W. Dunbar1, A. Kurbatov2, G.A. Zielinski2, W.C. McIntosh1, P.B. Price3, R.C. Bay3
1. E&ES Department, New Mexico Tech, Socorro, NM, 878012. Climate Change Institute, University of Maine, Orono, ME 04469-5790
3. Physics Department, University of California, Berkeley, CA 94720
Techniques for finding tephra layers in ice cores
• Visual identification
• Sulfate record
• Searching at depth of known eruptions
• Optical dust logger
Dep
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Tephra layers found in Siple Dome A ice core
A total of 40 layers with adequate ash for chemicalanalysishave been found.
Analysis of tephra layers in the Siple Dome core indicates derivation from:
Mt. Berlin (most layers)Mt. TakahePleiades Volcanic Center/Mt. Melbournelocal basaltic centers in the Royal Society Rangeat least one non-Antarctic volcano
Microbeam chemical analysis of glass shards in tephra layers coupled with statistical difference calculations allows:
1. Correlation to tephra layers in other ice cores
2. Correlation to eruptions of known age to provide time-stratigraphic markers
Siple Dome core Taylor Dome core
79.2 m1147 yrs bef. 1995??
Prefer 675+/-25 yrsbefore 1996
97.2-97.7 m703 yrs before 1995
Cross-correlation between ice cores
Conclusions• There are many identifiable and analyzable tephra layers in the Siple
Dome Ice Core, and probably will be in other WAIS cores• Most tephra layers are locally-derived, most having been erupted from
Mt. Berlin, located in West Antarctica, although Mt. Takahe, the Pleiades volcano and some basaltic centers are also represented.
• Several non-local tephra (probably South American) have also been identified
• Cross correlation of tephra layers between ice cores allow for better-dated cores to aid in dating of other cores. This also provide absolute time-stratigraphic markers between cores
• Chronology of tephra layers in the upper part of the Siple Dome core agree well with existing chronology, however agreement in the lower part of the core is less good.
• Further dating of source ashes (Mt. Berlin) may provide further information about age of lower Siple Dome tephra layers