Improved Glacial Isostatic Adjustment Models for Northern Canada

• Main Author: Simon, Karen
• Other Authors: James, Thomas Sinclair, Spence, George D.
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: glacial isostatic adjustment; relative sea-level; northern Canada; numerical modelling; Baffin Island; Canada; Hudson; Hudson Bay; Peltier; Baffin; Ice Sheet
• Online Access: http://hdl.handle.net/1828/5812

In northern Canada, the glacial isostatic adjustment (GIA) response of the Earth to the former Pleistocene Laurentide and Innuitian ice sheets contributes significantly to the Earth's past and ongoing sea-level change and land deformation. In this dissertation, measurements of Holocene sea-level change and observations of GPS-measured vertical crustal uplift rates are employed as constraints in numerical GIA models that examine the thickness and volume history of the former ice sheets in northern North America. The study is divided into two main sections; the first provides new measurements of Holocene sea-level change collected west of Hudson Bay, while the second presents a GIA modelling analysis for the entire study area of northern Canada. Radiocarbon dating of post-glacial deposits collected in an area just west of central Hudson Bay provides several new constraints on regional Holocene sea-level change. The field collection area is near a former load centre of the Laurentide Ice Sheet (LIS), and the sea-level measurements suggest that following deglaciation, regional sea level fell rapidly from a high-stand of nearly 170 m elevation just after 8000 cal yr BP to 60 m elevation by 5200 cal yr BP. Sea level subsequently fell at a decreased rate (approximately 30 m since 3000 cal yr BP). The fit of GIA model predictions to relative sea-level (RSL) data and present-day GPS-measured vertical land motion rates from throughout the study area constrains the peak thickness of the LIS to be 3.4-3.6 km west of Hudson Bay, and up to 4 km east of Hudson Bay. The ice model thicknesses inferred for these two regions represent, respectively, a 30% decrease and an average 20-25% increase to the load thickness relative to the ICE-5G reconstruction (Peltier 2004), generally consistent with other studies focussing on space geodetic measurements of vertical crustal motion. Around Baffin Island, the fit of GIA model predictions to RSL data indicate peak regional ice thicknesses of 1.2-1.3 km, a modest reduction compared to ...