Morphodynamics of Knickpoints Active Turbidity Current Channels

High-resolution bathymetric images of turbidity current channels reveal the existence of a wide range of bedforms within these systems. Knickpoints are the dominant bedform on a kilometre scale in most sandy systems. These knickpoints 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 knickpoints. What drives the formation of a knickpoint? 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 knickpoints in an active turbidity current channel on a fjord floor in British Colombia, Canada. These data show how trains of knickpoints migrate several hundred metres upstream every year. We use repeat surveys to show how knickpoints are a combined erosional-depositional feature. Furthermore, we have deployed several instruments over the knickpoints 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 knickpoints.