Date of Award

12-2015

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Quaternary and Climate Studies

Advisor

Andrei V. Kurbatov

Second Committee Member

Nelia W. Dunbar

Third Committee Member

Martin G. Yates

Abstract

Volcanic ash (fine tephra particles), due to their instantaneous geological deposition, are excellent markers for correlating terrestrial, marine, lacustrine and glacial depositional sequences. The composition, size, and shape of tephra particles can provide information about an eruption’s magnitude and timing, as well as about atmospheric circulation patterns and transport mechanisms at the time of the volcanic eruption. This thesis is focused on refining a methodology for extracting tephra particles from polar ice cores and developing analytical protocols for geochemical parameterization ("fingerprinting") of these very fine ash particles.

The first chapter summarizes existing tephra mounting techniques and describes new methodology developed during the course of this research. Use of this new sample preparation technique ensures robust capture of ultra fine tephra particles from ice core samples. In addition, uncertainties between EDS from the SEM and WDS measurements from an EPMA for various tephra particle sizes and compositions were estimated. In summary, oxide concentrations above one weight percent for SiO2, Al2O3, FeO, CaO, K2O, and Na2O showed good correspondence between EDS and WDS for rhyolite and basalt material with no observed influence of particle sizes on the measurements. For the P2O5, MgO, MnO, and TiO2 oxides with concentrations in measured tephra samples below one percent, comparison between EDS and WDS methods were not always consistent. These data contribute to developing a quantitative methodological framework that will be used in the future for designing quantitative tephra correlation algorithms for very fine tephra particles. Potentially very small, 1-5 m in size, tephra fragments can be transported for thousands of kilometers in the atmosphere from source volcanic eruptions and provide robust tephrochronological markers for intercontinental correlations of paleoclimate data sets. This chapter is the University of Maine research team’s contribution to the collaborative paper submitted by Nels Iverson (Ph.D. candidate at the New Mexico Institute of Mining and Technology, Department of Earth and Environmental Science) to Quaternary Geochronology in November 2015.

The second chapter is written as a manuscript that will be submitted to a peerreviewed journal. It describes the analysis of eight visible tephra layers from the RICE ice core. We established the source volcano for the 165 m tephra layer and correlated it with four other Antarctic ice cores (Siple Dome, Taylor Dome, Talos Dome, and WAIS Divide). We also correlated the 392 m tephra layer to the same layer found previously at three ice core sites: South Pole, Vostok, and EPICA Dome C. The work is a direct contribution to the AntT project.

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