Sticky stuff: Redefining bedform prediction in modern and ancient environments

Schindler, R.J. and Parsons, D.R. and Ye, L. and Hope, J.A. and Baas, J.H. and Peakall, J. and Manning, A.J. and Aspden, R.J. and Malarkey, J. and Simmons, S. and Paterson, D.M. and Lichtman, I.D. and Davies, A.G. and Thorne, P.D. and Bass, S.J. (2015) Sticky stuff: Redefining bedform prediction in modern and ancient environments. Geology. DOI: 10.1130/G36262.1

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The dimensions and dynamics of subaqueous bedforms are well known for cohesionless sediments. However, the effect of physical cohesion imparted by cohesive clay within mixed sand-mud substrates has not been examined, despite its recognized influence on sediment stability. Here we present a series of controlled laboratory experiments to establish the influence of substrate clay content on subaqueous bedform dynamics within mixtures of sand and clay exposed to unidirectional flow. The results show that bedform dimensions and steepness decrease linearly with clay content, and comparison with existing predictors of bedform dimensions, established within cohesionless sediments, reveals significant over-prediction of bedform size for all but the lowermost clay contents examined. The profound effect substrate clay content has on bedform dimensions has a number of important implications for interpretation in a range of modern and ancient environments, including reduced roughness and bedform heights in estuarine systems and the often cited lack of large dune cross-sets in turbidites. The results therefore offer a step change in our understanding of bedform formation and dynamics in these, and many other, sedimentary environments.

Item Type: Article
Subjects: Research Publications
Departments: College of Natural Sciences > School of Ocean Sciences
Date Deposited: 15 Apr 2015 02:20
Last Modified: 23 Sep 2015 02:48
ISSN: 0091-7613
Publisher's Statement: still no statement
URI: http://e.bangor.ac.uk/id/eprint/3688
Identification Number: DOI: 10.1130/G36262.1
Publisher: Geological Society of America
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