Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641544
Title: Moraines in the Chilean Lake District : form, process and chronology
Author: Bentley, Michael James
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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Abstract:
The moraines are made up of stratified glaciofluvial sediments overthrust on their proximal flanks by clay-rich tills composed of reworked glaciofluvial and glaciolacustrine sediments. A single model explains the location, morphology, sediments and structures of the moraines. The key point is that once a lake has formed, it allows the deposition of fine-grained lacustrine sediments which in turn affects the dynamics of the glacier during any subsequent advance and retreat. A relative chronology shows a number of similarities and differences between the behaviour of the Puyehue and Rupanco glaciers. Both show the same broad pattern of advance and retreat but Rupanco lagged Puyehue in its response to climate change. The shorter response time of Puyehue also means it was more likely to reach the culmination of an advance in response to a climatic fluctuation. The empirical evidence of differential response has been used as a strong test of a glaciological model developed in parallel with this research and helps to explain the geomorphological record. The differences in response reflect the more uniform, steeper longitudinal bed slope of the Puyehue glacier basin, and the influence of calving dynamics. Radiocarbon dating has confirmed that the moraines belong to the last glaciation and that the timing of advances demonstrates a similar pattern to other outlets. All the glacier basins show advances at c.21 ka and c. 14.5 ka but the precise timing in individual basins may have differed by as much as 1500 years. There are as number of implications to be drawn from the moraine-forming model and the chronologies of the Puyehue and Rupanco glaciers. In areas where temperate glaciers advance into lakes they are likely to be partly decoupled from climate. Field evidence of these advances will be closely superimposed and detailed morphostratigraphic and lithostratigraphic criteria are needed in conjunction with radiocarbon dating to distinguish different advances. Topography also plays an important role in determining glacier response. These are additional factors to be considered when establishing glacial chronologies from such moraine sequences.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.641544  DOI: Not available
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