Influence of benthic sediment transport on cold‐water coral bank morphology and growth: the example of the Darwin Mounds, north‐east Atlantic

• Published in: Sedimentology
• Main Authors: WHEELER, ANDREW J., KOZACHENKO, MAXIM, MASSON, DOUG G., HUVENNE, VEERLE A. I.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2008
• Subjects: North East Atlantic
• Online Access: http://dx.doi.org/10.1111/j.1365-3091.2008.00970.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-3091.2008.00970.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-3091.2008.00970.x

Abstract The Darwin Mounds are small (up to 70 m in diameter), discrete cold‐water coral banks found at c. 950 m water depth in the northern Rockall Trough, north‐east Atlantic. Formerly described in terms of their genesis, the Darwin Mounds are re‐evaluated here in terms of mound growth processes based on 100 and 410 kHz side‐scan sonar data. The side‐scan sonar coverage is divided into a series of acoustic facies representing increasing current speed and sediment transport/erosion from south to north: pockmark facies, ‘mounds within depressions’ facies, Darwin Mound facies, stippled seabed facies and sand wave facies. Mound morphometric changes are quantified and show a south‐to‐north divergence from an inherited morphology, reflecting the outline of coral‐colonized fluid escape structures, to developed, downstream elongated, elevated mound forms. It is postulated that increasing current speeds and bedload sand transport favour mound growth and development by a process of enhanced sand sedimentation within mounds due to current deceleration by frictional drag around coral colonies. Comparisons are made with similar growth processes attributed to comparably sized cold‐water coral mounds in the Porcupine Seabight, offshore Ireland.