Taylor Glacier as an archive of ancient ice for large- volume samples : Chronology, gases, dust, and climate

• Main Author: Baggenstos, Daniel
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: eScholarship, University of California 2015
• Subjects: UCSD Dissertations; Academic Earth Sciences. (Discipline); Antarctic; Taylor Glacier; Taylor Dome; Antarc*; Antarctica; ice core; Ice Sheet; North Atlantic
• Online Access: http://www.escholarship.org/uc/item/9wn8789k; http://n2t.net/ark:/20775/bb5428457m

The aim of this dissertation is twofold, to develop a new ice sheet margin site on Taylor Glacier as a paleo-climate archive, and to resolve the controversy of the Taylor Dome chronology. The motivation for the former is that ice from deep ice core drilling projects is a precious commodity because only a finite amount of it is available from each core. This precludes measurements of trace constituents that need large sample sizes. Ice margin sites can provide an ice archive that complements the deep drilling efforts. We present a suite of gas measurements from Taylor Glacier, Antarctica, that allow us to date the outcropping ice. We find that ice from the last glacial cycle is exposed at the glacier surface over tens of kilometers. Every climatic interval of the last 125,000 years has been identified, from the penultimate interglacial to the Holocene, laying the foundation for future work. The age of the ice generally increases as one moves down-glacier, but at most locations the across flow age gradient is at least a magnitude larger. We have developed a high resolution age model for an across flow transect covering 50,000 to 8,000 years ago, that offers the chance to study the Last Glacial Maximum and the deglaciation in detail. We also describe and interpret large scale folding observed in the stratigraphy that can provide information on the deformation history. The second focus of this dissertation is to revisit the Taylor Dome chronology, which is at the center of a controversial finding suggesting a direct link of Taylor Dome climate and changes happening in the North Atlantic during the deglaciation. We use measurements of calcium and H₂O isotopes in a true horizontal ice core from Taylor Glacier to show unambiguously that the Taylor Dome area temperature history is synchronous with the warming observed in other Antarctic ice cores, and not with North Atlantic records. We also find that the accumulation rate during the Last Glacial Maximum was extremely low, the overestimation of which led to the error in the original time scale. There is evidence from noble gas isotopic composition that a substantial convective zone formed during the same period. We present a new Taylor Dome time scale to replace the now obsolete original Taylor Dome chronology