GEOSCAN Search Results: Fastlink


TitleGlaciofluvial systems of glaciated Canada: insights from the barren lands and areas of thick sediment cover in Canada
AuthorSharpe, D; Russell, H; Pugin, A; Lesemann, J
SourceCANQUA-CGRG 2013. Canadian Quaternary Association and Canadian Geomorphology Research Group Conference, Program and Abstracts.; by CANQUA-CGRG; 2013 p. 215
Alt SeriesEarth Sciences Sector, Contribution Series 20130060
MeetingCANQUA-CGRG 2013; Edmonton; CA; August 18-22, 2013
MediaCD-ROM; digital
Subjectssurficial geology/geomorphology; glacial deposits; glaciofluvial deposits; glacial landforms; eskers; moraines; erosion; aquifers; glaciation; Laurentide Ice Sheet; Quaternary
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
AbstractThe barren lands of northern Canada display glacial landforms in exceptional detail, such as the vast esker networks, mapped since the first use of remote sensing (aerial photographs), and containing elements of dendritic and more parallel network organization. Recent field observations along the trend of esker networks highlight zones of erosion and scour that parallel esker ridge lines. These erosion zones scoured 2-30 m deep, are ~0.2 to 5 km wide, spaced ~5'15 km apart, and are mapped sub-parallel for ~10 to >100 km in length. They have sharp to vague boundaries, carry s-form and abrasion marks on exposed bedrock, show undulating longitudinal profiles and are referred to as glaciofluvial corridors. Glaciofluvial corridors appear to be equivalent to tunnel valleys /channels elsewhere in glacial landscapes mantled with thicker sediment. Comparison of glaciofluvial corridors with inferred tunnel valleys in thicker sediment-mantled glaciated terrains in Canada is instructive where high-quality subsurface data exist. Recent aquifer characterization studies across Canada (e.g. Oak Ridges Moraine and prairie regions) have provided high-resolution geophysical and continuous core data that add to our understanding of the style, character and timing of sediment fills within tunnel valleys, in addition to valley geometry and sediment architecture. Tunnel valleys can be eroded in rock, yet when eroded into sediment they are 10-200 m deep, ~0.2-10 km wide, spaced 10-20 km apart (in places) and are ~10- >100 km long in sub-parallel to anabranched networks. Both glaciofluvial corridors and tunnel channels/valleys are well-defined systems within regional unconformities on the glaciated landscape.

Tunnel valleys and glaciofluvial corridors, though largely erosional landforms, also contain sediment fills of variable origin. Some contain mainly post-glacial deposits and little, if any, sediment fill associated with the formative events during glaciation. In contrast, fills in some tunnel valleys can be complex and of multiple ages. High-quality core data reveal the presence of thick, coarse-grained, high-energy fills interpreted as waning-stage deposits related to the scoured surfaces of the tunnel valley.

The distribution, morphology, and sedimentology of glaciofluvial corridors and tunnel valleys lead to hypotheses of their formative processes and the possible spatial and temporal relationships between formation of corridors/ tunnel valleys/channels and eskers. Ultimately, these landscape elements shed light on the glacial/deglacial dynamics, retreat styles and patterns, and the paleo-hydrology of the former Laurentide Ice sheet.
Summary(Plain Language Summary, not published)
The barren lands of northern Canada display glacial landforms in exceptional detail, including the vast esker (former subglacial river) networks, mapped since the first use of aerial photographs. They contain tree-like esker networks where recent field observations along the trend of these networks highlight zones of erosion and scour that parallel esker ridges. Meltwater erosion corridors in the north are equivalent to large meltwater valleys in the south, where glacial landscapes are mantled with thick sediment. Meltwater corridors are useful for mineral exploration in northern regions, while meltwater valleys in thick sediment terrains are important links to vast groundwater resources in southern Canada.