--> Flow Dynamics and Depositional Features of Turbidity Currents in NAMOC of the Labrador Sea, Based on HAWAII-MR-1 Side-Scan Sonar Imagery, by I. Klaucke, R. Hesse, W. B. F. Ryan, and D. J. W. Piper; #90986 (1994).

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Abstract: Flow Dynamics and Depositional features of Turbidity Currents in NAMOC of the Labrador Sea, based on HAWAII-MR-1 Side-Scan Sonar Imagery

Ingo Klaucke, Reinhard Hesse, William B. F. Ryan, David J. W. Piper

Meander radii of 18-60 km of the Northwest Atlantic Mid-Ocean Channel (NAMOC) generally show an increase downchannel, but the variation is not entirely systematic. Channel morphology constrains calculated velocities of turbidity currents to values between 2.2 and 7.2 m/s. The upper limit is placed by the relative levee height (right levee consistently higher than left levee), which is possible only if the Coriolis force exceeds the centrifugal force everywhere between 59 and 44° N. Pebbles 6 cm in diameter recovered from the channel floor, however, require much higher flow velocities for bedload transport.

Erosional and depositional features related to these channelized currents are revealed on side-scan images in spectacular detail: (1) In high sinuosity reaches, a narrower channel has a deeply incised talweg and adjacent point bars that seem to carry sand dunes or gravel waves. (2) In low sinuosity reaches, the channel is wider with a braided channel floor displaying several talwegs and sand bars. (3) At sharp meander bends deeper, coarse-grained levels of the currents have generated sandy washover fans by spill over. (4) Bright areas on the channel floor are slumps, which are concentrated on inner right-turning meander bends, and are related to gullies on the channel wall.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994