| Summary: | The study of past ice sheets, such as the Laurentide Ice Sheet (LIS), which covered most of northern North America during the last glaciation (last ~100-kyr), provides critical knowledge about the long-term behaviour of ice sheets, how they modified landscapes and the sedimentary record, and how they responded to external climate forcings. The LIS had a complex evolution including several changes in its configuration (e.g., ice sheet extent, its surface topography and its thickness). This is essentially known through multiple studies of ice-flow indicators and glacial landforms and sediments. However, conflicting ice flow reconstructions exist for many regions of the LIS, with implications for the overall understanding of the long-term evolution of ice sheets. One of these regions, within the Quebec-Labrador (Q-L) sector of the LIS, is located in northern Quebec and western Labrador. The Q-L sector is one of the largest ‘inner-regions’ of the LIS where the main ice divides formed with an unresolved ice-flow history. Specifically, a major landform boundary, commonly referred to as the horseshoe unconformity, has been the source of conflicting paleoglaciological reconstructions. Changes in the thermal regime at the base of the ice sheet have been invoked to explain this landscape, whereby relict fragments of the ice sheet imprint are partially preserved following a switch from warm-based to cold-based conditions. However, previous research has disagreed on the sequence of events, the relative timing/duration, and significance. Large areas within the former Q-L sector also lack field-based evidence and detailed data regarding ice-flow indicators, sediment transport, and other characteristics (e.g., weathering), which contributed to the uncertainties in ice sheet reconstructions. Therefore, a study area within the inner-region of the Q-L sector was selected to investigate its glacial evolution. The overall goal of this thesis is to characterize the glacial sediments and their distribution across the study area and ...
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