[S-CG65] [EE] Turbidity current: from triggers for the generation to the depositional and morphological processes

[SCG65-07] Direct observation of knick point acitivity in turbidity current channels

★Invited papers

*Matthieu Cartigny¹, John Hughes Clarke², Cooper Stacey³, Sophie Hage⁵, Daniel Parsons⁴, Peter Talling¹, Maria Azpiroz⁵, Michael Clare⁶, Joris Eggenhuisen ⁷, Jenny Gales⁶, Jamie Hizzett⁵, James Hunt⁶, Gwyn Lintern³, Steve Simmons⁴, Esther Sumner⁵, Age Vellinga⁵, Daniella Vendettuoli⁵, Jon Wood⁸ (1.Department of Geography and Earth Sciences, Durham University, UK, 2.Center for Coastal and Ocean Mapping, University of New Hampshire, USA, 3.Natural Resources, Geological Survey of Canada, Canada, 4.School of Environmental Sciences, Hull University, UK , 5.School of Ocean and Earth Science, University of Southampton, UK, 6.Marine Geoscience, National Oceanography Centre, UK, 7.Department of Geosciences, Utrecht University, The Netherlands, 8.Ocean Data Technologies, Inc., Hyannis, USA)

Keywords:Turbidity currents, submarine channels, knick points

High-resolution bathymetric images of turbidity current channels reveal the existence of a wide range of bedforms within these systems. Knick points are the dominant bedform on a kilometre scale in most sandy systems. These knick points are thought to initiate and maintain submarine channels, and they would therefore play a key role the transport of sediment and nutrients to the deep sea. In contrast to their important role very little is known about knick points. What drives the formation of a knick point? Are they remnant headwalls of landslide, or are they related to turbidity currents? Are they a purely erosional feature? Do they have any preservation potential in the rock record?

Here we present data collected from knick points in an active turbidity current channel on a fjord floor in British Colombia, Canada. These data show how trains of knick points migrate several hundred metres upstream every year. We use repeat surveys to show how knick points are a combined erosional-depositional feature. Furthermore, we have deployed several instruments over the knick points to study how the knick points interact with the passing turbidity currents. Finally, we use repeat surveys and cores to explore the potential architecture and facies association associated to knick points.