Patagonian glacial reconstructions at 49°S

Geiger, Alessa J. (2015) Patagonian glacial reconstructions at 49°S. PhD thesis, University of Glasgow.

Abstract

Patagonia has one of the most extensive and well preserved glacial geomorphic records of anywhere else in the world. This study provides empirical constraints of Patagonian Ice Sheet (PIS) configuration and dynamics during the last two glacial cycles and the Holocene at 49°S. In particular a chronology of palaeo-ice surface elevations, thickness changes and ice-thinning rates is developed. Cosmogenic surface exposure dating across eight mountain transects at Hielo Patagonico Sur (HPS) outlet glaciers' Viedma and Chico, and from eastern facing mountain valley glaciers, is utilised to reconstruct PIS ice-surface elevation changes through time. The earliest dated glacier ice thickness marker falls into MIS6 (Marine Isotope Stage). The last glacial cycle is characterised by continuous ice-surface elevation lowering from a maximum at MIS5a to the Antarctic Cold Reversal (ACR). Large scale PIS cover occurred between ca. 40-47 kyrs, in both the HPS outlet glaciers and the eastern mountain valleys. This regional ice-cover considerably pre-dates the global Last Glacial Maximum (gLGM). A gLGM vertical ice surface expression is absent from the study area. A minor re-advance and/or stillstand at ca. 18 kyrs is recorded by the valley glaciers, but is not evident at the HPS outlet glaciers. Glacier Viedma records a prominent ice elevation during the ACR with rapid thinning at the end of the climate perturbation. Ice-surface lowering from the ACR limit continues with acceleration toward the late-Holocene. The PIS palaeo-ice elevation and thinning record presented here is sensitive to internal PIS dynamics, local and global climate forcing acting on different timescales, with glacier response to climate perturbation strongly linked to glacier catchment size and distance from the main source of precipitation at 49°S.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Cosmogenic nuclides, geomorphology, glaciers, palaeoclimate, Patagonia, South America
• Subjects: G Geography. Anthropology. Recreation > GB Physical geography; Q Science > QD Chemistry; Q Science > QE Geology
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences > Geography
• Supervisor's Name: Fabel, Dr. Derek and Glasser, Prof. Neil
• Date of Award: 2015
• Embargo Date: 28 May 2020
• Depositing User: Ms Alessa J Geiger
• Unique ID: glathesis:2015-6404
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 04 Jun 2015 15:29
• Last Modified: 12 Jun 2019 08:36
• URI: https://theses.gla.ac.uk/id/eprint/6404