Flow parameters of turbidity currents in a low‐sinuosity giant deep‐sea channel

• Published in: Sedimentology
• Main Authors: KLAUCKE, INGO, HESSE, R., RYAN, W. B. F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Northwest Atlantic
• Online Access: http://dx.doi.org/10.1111/j.1365-3091.1997.tb02180.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3091.1997.tb02180.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3091.1997.tb02180.x

ABSTRACT Flow parameters (velocity and density) for turbidity currents in the Northwest Atlantic Mid‐Ocean Channel (NAMOC) have been determined based on two different approaches, channel geometry and grain‐size distributions of turbidites. Channel geometry has been obtained by a quantitative morphological analysis of the NAMOC which shows three genetically different segments in the upper 2000 km: (1) an upper 350 km‐long ‘equilibrium channel’, (2) a middle 700 km‐long ‘modified equilibrium channel’and (3) a lower ‘basement‐controlled channel’which is more than 1000 km‐long. In contrast to other meandering submarine channels the NAMOC has very low sinuosities and gradients. A consistently higher right‐hand levee limits mean flow velocities to 3ms −1 and channel geometry indicates mean flow velocities of 0·86 m s −1 that decrease within the equilibrium channel to 0·05 m s −1 . Grain‐size distributions on the levees and in the channel suggest strong vertical velocity and density gradients for bank‐full flows with velocities of up to 8 m s −1 and excess densities up to 87 kg m −3 at the base, and 0·45 m s −1 and 4 kg m −3 at the top. The internal shear produced by these strong vertical gradients results in a decoupling of the current head and body. Channel geometry appears to be mainly the result of the slowly moving dilute body of the current.