Knickpoint Migration and Long-term Submarine Channel System Evolution within Bute Inlet, British Columbia, Canada
Abstract
Submarine channels play an important role as the active conduits for turbidity currents that transport large amounts of sediments from continental shelves into the deep sea, thus forming some of the largest sand reservoirs on Earth. Knickpoints, have been identified as a key geomorphological feature within a range of submarine channels, migrating upstream along the channel during events. There is limited direct measurements that actively monitor turbidity currents and channel knickpoint migration, such that the processes acting on knickpoint dynamics can be quantified and understood. Here we present a sequence of high-resolution seafloor bathymetric surveys, alongside the collection of data on turbidity current flow velocity, sediment cores and bed samples in Bute Inlet, BC, Canada. The results reveal that, on average the upstream migration rate of a train of knickpoints exceeds 100 metres per year (based on change maps across 2008 to 2018). The various knickpoints within the channel migrate at different speeds, both temporally and spatially. In order to explain these processes, a series of turbidity currents were recorded by 6 moored ADCPs from the zone proximal to the delta at the fjord head to channel lobe beyond 600 m depth, across the 2016 freshet. These data enable the flow velocity structure and suspended sediment concentration over a study knickpoint to be quantified. These data are being used to explore the linkage of delta source to lobe deposit through knickpoint migration processes, terrace formation and temporary storage of fluxed sediment across various system level time-space scales.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMOS13C1504C
- Keywords:
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- 1824 Geomorphology: general;
- HYDROLOGYDE: 3002 Continental shelf and slope processes;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3022 Marine sediments: processes and transport;
- MARINE GEOLOGY AND GEOPHYSICSDE: 3045 Seafloor morphology;
- geology;
- and geophysics;
- MARINE GEOLOGY AND GEOPHYSICS