CGRG Bibliography of Canadian Geomorphology
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Author : Barendregt, R.W.; Dredge, L.A.; Nielsen, E.; Roy, M.; Verosub, K.L.; and Enkin, R.J.
Date : 2001.
Title : Paleomagnetism of Quaternary sediments in Hudson Bay Lowland of Manitoba, Canada.
Publication : Canadian Quaternary Association/ Association canadienne pour l'etude du Quaternaire, Annual Meeting 2001. Whitehorse, Yukon Territory, August 20 – 24, 2001.
Issue :
Page(s) :
Abstract
Thick sequences of Quaternary sediments are exposed in the Hudson Bay Lowland along the banks of major river valleys. Both glacial and interglacial sediments are present. Four tills have been identified on the basis of provenance, lithologic composition, texture and colour, and from oldest to youngest are referred to as the Sundance, Amery, Long Spruce, and Sky Pilot till. Sundance till is a sandy granitic till of northwestern (Keewatin) provenance, while the others are calcareous and of eastern (Labrador) provenance. Interglacial beds of Sangamon and pre-Sangamon age have been identified at a number of sites, and have been correlated on the basis of their stratigraphic position relative to the tills, and on paleoecological criteria. Five sections in the lower Nelson/Hayes River area were selected for paleomagnetic study because they contain the most complete Quaternary stratigraphic record for this region. Collectively, the deposits represent a very considerable span of time, probably recording most if not all major glacial and interglacial events. Their record provides direct evidence for: glaciations of both eastern and western provenance, extensive suites of interglacial sediments, ice-free conditions over Hudson Bay, the raising and lowering of sea and land surfaces, and soil development. Since no absolute dating techniques could be applied to the older sediments, paleomagnetic measurements were made to determine whether reversely magnetized Matuyama Zone (2.6 - 0.78 Ma) sediments are present. All units yielded normal magnetizations, indicating that the Quaternary record in the Hudson Bay Lowland can be assigned to the Brunhes Chron (<0.78 Ma) and is thus entirely of middle to late Pleistocene age. These results compare favorably with other sites within the Canadian Interior Plains and the adjacent US Great Plains, which reveal only normally magnetized glacial deposits. Collectively, the magnetostratigraphy of those sites and the sites described here from the Hudson Bay Lowland strongly suggest that continental glaciation occurred repeatedly in this region during the Brunhes Chron. The distribution and extent of ice in North America during glacial periods was apparently very different during the Matuyama from that during the Brunhes Chron. While ice was present in the Cordillera and in northeastern North America during the Matuyama Reversed Chron, it appears to have been largely absent from large areas of the Prairie Provinces of Canada and adjacent areas of the United States.
Bibliography of Canadian Geomorphology