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FOURIER
GRAIN SHAPE ANALYSIS OF COLD COASTAL SANDS, CANADA
M.W. MACKAY and I.P. MARTINI กก
Department of Land Resource Science, University of Guelph,
Guelph, Ont. Canada The shape and surface textures of quartz grains from the fine sand fraction of coastal sediments from arctic (Foxe Basin), subarctic (Hudson‑James Bay) and cold temperate (Wasaga Beach) environments were analyzed using high resolution Fourier shape analysis and scanning electron microscopy. Significant differences found between arctic samples and the others and are predominantly related to provenance rather than modern climate‑dependent processes. The shape frequency distributions of most samples from Foxe Basin are typically influenced by the presence of well rounded and spherical aeolian grains, presumably derived from reworked Pleistocene deposits. Other samples exhibit very distinct shape frequency distributions associated with very angular grains derived from the weathering of local igneous and metamorphic bedrock. Large deposits with well rounded aeolian grains are missing from the subarctic and cold temperate regions. At Wasaga Beach, however, changes have been detected between beaches and coastal dunes, with the latter containing a greater proportion of slightly more rounded spherical grains. This difference has been interpreted to be due primarily to a differential shape sorting processes, rather than abrasion, because of the short transport (tens of meters to few kilometers) from the beaches to the vegetated coastal dunes. |
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