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

th in

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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

Mt. Takahe8.2+/-2.7

Mt. Berlin10.3+/-2.7

Mt. Hudson11.1+/-1.8

TIf

Mt. Hudson11.1+/-1.8

Mt. Berlin10.3+/-2.7

Mt. Takahe8.2+/-2.7

Mt. Berlin24.7+/-1.5

Mt. Berlin<92.2+/-0.9

Mt. Berlin<118.7+/-2.5??

Mt. Berlin18.2+/-5.8

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