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Title: The application of cosmogenic exposure dating to glacial landforms : examples from Antarctica and Patagonia
Author: Fogwill, Christopher J.
ISNI:       0000 0004 2716 8946
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2003
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Through the measurement of the concentrations of the in situ cosmogenic nuclides 1°Be and 26A1 within rock surfaces, this thesis has attempted to solve previously intractable problems regarding the timing and magnitude of glaciation during the last glacial cycle in the vicinity of the Drake Passage. In southernmost Patagonia we have been able to constrain the timing of two major advances of the formerly expanded Patagonian Ice Sheet during the last glacial interglacial transition. In the past these have been in question due to the paucity of radiocarbon dates, in the extremely and conditions prevailing to the east of the southern-most Andes. The timing of deglaciation over 16° of latitude appears to be synchronous, although the magnitude of glaciation differed markedly from latitude to latitude. In southernmost Patagonia maximum ice extent was achieved before 26 ka BP, and deglaciation occurred rapidly at around 17 ka Bp. This is indistinguishable from that of the last glacial period in the Northern Hemisphere. This is interesting as it at a time when insolation was rising to its maximum in the southern hemisphere. The similarity of glacial chronologies from mid-latitudes in both hemispheres indicate that global atmospheric signaling is a major driving mechanism of climate. Results from Antarctica indicate a much more complex picture, with the Antarctic Peninsula and the Shackleton Range Mountains producing very different patterns of deglaciation. These data suggest that glaciation of the Antarctic Peninsula has been forced predominately by eustatic sea level fluctuations, with a complex spread of ages, suggesting ice surface thinning at times of rapid sea level rise. The pattern of deglaciation is very different in the Shackleton Mountains of Antarctica where Quaternary glacial fluctuations have been characterised by extreme stability, with no evidence of substantial ice thickening suggested by some hypotheses. The concentrations of radionuclides demonstrate that these summits have not been covered by ice for significant periods during the Quaternary. The implication is that this periphery of the East Antarctic Ice Sheet has not thickened by more than 400 m in the last 3 million years. Although these are only preliminary results, they place important constraints on glacial modelling studies and research regarding ice thickening of the Filchner Ice Shelf during glacial maxima. In turn these data have implications for ice-sheet controls of the global seawater budget during the last glacial interglacial cycle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available