Abstract

The inner shelf of the Canadian Beaufort Sea is characterized by a succession of near-surface fine-grained facies changes. Seaward of shoreface sands and silts, these facies are: (1) thin-bedded silt and clay couplets (< 1 cm thick); (2) massive to graded medium to thick-bedded silt beds (up to 20 cm thick); (3) thin silt beds (< 2 cm thick) with thick interbeds of bioturbated silty clay; and (4) bioturbated silty clay with no silt beds. These facies are related to wave action at the seabed. The massive to graded medium to thick-bedded facies occurs between water depths of 4.2 m and 5.5 m and is interpreted to result from resuspension events by waves during storms. A nearbed region of suspended sediment concentration (SSC), observed near the 5 m isobath, increased in concentration during moderate storms. Time series of nearbed SSC and wave heights in 5.9 m of water recorded rapid resuspension resulting in SSC values of 4,000 mg/L during a severe storm. The thin-bedded silt and clay facies found shoreward of this resuspension zone is interpreted to result from attenuation of wave energy in the resuspension zone. The amount of resuspension decreases shoreward, resulting in thinner redeposited beds. Seaward of the resuspension zone, the frequency of bottom resuspension decreases with increasing water depth, reflecting the lower frequency of very large storm waves. This is reflected in the deeper water facies where bioturbated clay becomes the dominant facies, with thin silt beds representing infrequent bottom resuspension during the largest storms.

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