February FCGS Meeting Presents Laura Hartman: Investigations Into the Advancement of Cryptotephra Geochemical Fingerprinting and Tephrochronology

ABSTRACT

Two of the on-going challenges in ice core based tephrochronological work is the extraction and measurement of the geochemical composition of ultra-fine tephra particles (<10 μm). When a volcanic source can be accurately identified using volcanic glass particle geochemistry, it may provide a robust time reference for the ice core’s timescale. In addition, the presence of an identifiable tephra layer may also suggest atmospheric pathways at the time of deposition, or assist in reconstructing volcanic forcing of climactic state for a specific event. Although traditional geochemical measurements are taken using EMPA-WDS, the grain size can be a limiting factor. Therefore, this work attempts to further improve SEM-EDS based tephra measurements to unveil their fullest potential.
The first section of this work explores the use of recent particle mounting methodological advancements to examine the volcanic sources of tephra horizons in ice cores from Antarctica and the Swiss-Italian Alps. The second section of this work evaluates the results of testing a fully quantitative SEM-EDS geochemical measurement protocol developed at the National Institute of Standards and Technology (NIST) called DTSA-II.

BIOGRAPHY: Laura Hartman, BLM

Laura Hartman received her BSc in Geoscience from Pennsylvania State University. Her senior thesis focused on paired xenoliths and basalts from Western Turkey in order to constrain melting regimes. She then went on to gain her MSc in Quaternary and Climate Science at the University of Maine. Her MSc thesis focused on tephrochronology and attempting to develop new techniques for cryptotephra geochemical fingerprinting. During and after school, she shifted her focus to working with public lands. In the beginning, this was through a series of internships with the Bureau of Land Management (BLM), Forest Service (USFS), and National Park Service (NPS). With these agencies, she worked as a Cave Technician in Shoshone, ID (BLM), Geologist in Winnemucca, NV (BLM), Geomorphic Technician in Umpqua National Forest, OR (USFS), Environmental Educator at Oregon Caves National Monument and Preserve, OR (NPS), and Education Technician at Colorado National Monument, CO (NPS). Laura now works with the Bureau of Land Management in Dolores, CO as an Environmental Protection Specialist. She’s new to southwestern Colorado, and is looking forward to new challenges and experiences!

SCHEDULE

• 5:30pm – Social
• 6:00pm – Dinner
• 6:45pm – FCGS Business/Announcements
• 7:00pm – Talk begins