Abstract

Soft, highly reduced, fluid-like muds are accumulating at an average rate of 10 cm/yr on a seabed at Cape Lookout Bight that is neither below wave base during frequent winter storms nor subjected only to negligible fairweather tidal currents. Much of the sediment settling to the bottom is in the form of enormous (up to 1 cm long) aggregates of "marine snow" that are generally believed to occur only in quiet oceanic environments. Field measurements show that near-bottom currents are typically 25-50 cm/sec with directions that appear to be decoupled from the well-defined rise and fall of tide. A tendency toward extended ebb flows (missed floods) suggests that sediments may be transported into the bight from Barden Inlet for prolonged periods of time. The lack of correlation between suspended-sediment concentration and near-bottom current speed or direction indicates that little or no resuspension occurs during tidal flows or during 1-2 hr storms with winds in the 15-20 m/sec (30-40 kt) speed range. High vertical flux of marine snow, together with an apparent resistance of bottom sediments to resuspension, offer an explanation for this and other backbarrier mud deposits that are impossible to explain by the settling of individual particles and difficult to explain by the settling of salt-floc-sized aggregates.

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