Carbonate till as a soft bed for Pleistocene ice streams on the Canadian Shield north of Lake Superior
Silty carbonate till derived from erosion of Paleozoic carbonate and Proterozoic rocks within and adjacent to Hudson Bay covers extensive areas of the Canadian Shield north of Lake Superior. It is hypothesized that this carbonate till could have acted as low-resistance substrata for overriding ice s...
| Published in: | Canadian Journal of Earth Sciences |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1989
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/e89-191 http://www.nrcresearchpress.com/doi/pdf/10.1139/e89-191 |
| Summary: | Silty carbonate till derived from erosion of Paleozoic carbonate and Proterozoic rocks within and adjacent to Hudson Bay covers extensive areas of the Canadian Shield north of Lake Superior. It is hypothesized that this carbonate till could have acted as low-resistance substrata for overriding ice streams by deforming and (or) supporting high subglacial water pressures. Contrary to assumptions presented in some current models for ice flow within the Laurentide Ice Sheet, it need not be assumed that Shield terrain in these areas acted as a rigid bed, generating large basal shear stresses and inhibiting ice flow. Indeed, erratic-dispersal patterns, long-distance glacial transport, and splayed patterns of ice-flow indicators in areas of thick till cover may be better explained by rapid ice-flow events or ice streams, enhanced by the thickness, distribution, impermeability, and susceptibility to deformation of fine carbonate till. |
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