Geochemical and Geostatisical Analyses of Quaternary Climate Variability over Millennial-to-Orbital Timescales

• Main Author: Barth, Aaron M.
• Other Authors: Clark, Peter U., Brook, Edward, Carlson, Anders, Bailey, John, Pisias, Nicklas, College of Earth, Ocean, and Atmospheric Sciences, Oregon State University. Graduate School
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Oregon State University
• Subjects: Ice sheets > Ireland > History; Paleoclimatology > Quaternary; Climatic changes > History; Ice cap; Ice Sheet
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/t435gj93t

The goal of dissertation research was to use geochemical, statistical and geological methods to constrain and understand climate variability over several different time scales. Specifically, I have addressed three questions regarding past climate change: (1) how does the record of Irish cirque glaciers constrain the dimensions of the Irish Ice Sheet during and since the Last Glacial Maximum (LGM);(2) what is the record of millennial-scale glacier variability in Ireland during the last glaciation; and (3) how did variability of various components of the climate system interact to contribute to the evolution of climate over the last 800,000 years.The first chapter involves constraining the vertical and spatial extent of the Irish Ice Sheet (IIS). Reconstructions of the LGM IIS are widely debated, in large part due to limited age constraints on former ice margins and due to uncertainties in the origin of the trimlines used to identify vertical ice limits. The greatest differences exist in southwestern Ireland where reconstructions either have complete coverage by a contiguous IIS that extends onto the continental shelf or a separate, southern sourced Kerry-Cork Ice Cap (KCIC) with more limited spatial and vertical extent. New ¹⁰Be surface exposure ages from two moraines in a cirque basin in this region provide a unique constraint on ice thickness for this region insofar as the presence of a cirque glacier at a given time clearly indicates that the site was not covered by the IIS. My new ¹⁰Be ages from these two moraines show that the central mountains in southwestern Ireland were not covered by the IIS or a KCIC since at least 24.5±1.4ka, thus supporting the more-limited reconstructions of the IIS at the LGM, indicating a reduced contribution to sea-level change and a smaller loading of the solid Earth,which is consistent with models of glacial isostatic adjustment to the IIS.The second chapter presents research that has developed a record of millennial-scale variability in former Irish cirque glaciers between ~25 ...