The role of fully coupled ice sheet basal processes in quaternary glacial cycles
Bed conditions such as meltwater pressurization and unconsolidated sediment cover (soft versus hard bedded) strongly impact ice sheet sliding velocities. How the dynamical processes governing these conditions affect glacial cycle scale ice sheet evolution has been little studied. The influence of su...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
2023
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| Online Access: | https://research.library.mun.ca/16173/ https://research.library.mun.ca/16173/1/converted.pdf |
| Summary: | Bed conditions such as meltwater pressurization and unconsolidated sediment cover (soft versus hard bedded) strongly impact ice sheet sliding velocities. How the dynamical processes governing these conditions affect glacial cycle scale ice sheet evolution has been little studied. The influence of subglacial hydrology and glacial sediment production and transport is therefore largely unknown. Here I present a glaciological model Glacial Systems Model (GSM) with the to-date most complete representations of fully coupled subglacial hydrology and sediment production and transport for the glacial cycle continental scale context. I compare the influence of of several types of subglacial hydrology drainage systems on millennial scale variability and examine the role dynamical sediment processes potentially played in the mid-Pleistocene Transition (MPT) from 41 to 100 kyr glacial cycles. Subglacial hydrology has long been inferred to play a role in glacial dynamics at decadal and shorter scales. However, it remains unclear whether subglacial hydrology has a critical role in ice sheet evolution on greater than centennial time-scales. It is also unclear which drainage system is most appropriate for the continental/glacial cycle scale. Here I compare the dynamical role of three subglacial hydrology systems most dominant in the literature in the context of surge behaviour for an idealized Hudson Strait scale ice stream. I find that subglacial hydrology is an important system inductance for realistic ice stream surging and that the three formulations all exhibit similar surge behaviour. Even a detail as fundamental as mass conserving transport of subglacial water is not necessary for simulating a full range of surge frequency and amplitude. However, one difference is apparent: the combined positive and negative feedbacks of the linked-cavity system yields longer duration surges and a broader range of effective pressures than its poro-elastic and leaky-bucket counterparts. The MPT from 41 kyr to 100 kyr glacial cycles was one ... |
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