Channel trajectories control deep‐water stratigraphic architecture

Morris, Paul D.; Sylvester, Zoltán; Covault, Jacob A.; Mohrig, David

doi:10.1002/dep2.189

Cited by 7 publications

(1 citation statement)

References 69 publications

(157 reference statements)

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“…The migration of channel threads in braided rivers significantly impacts fluvial landscapes, and sedimentary deposits (Ganti et al., 2020; Morris et al., 2022; Steel et al., 2022; Wickert et al., 2013). This study analyzes the style of channel thread migration in a specific laboratory experiment and finds that patterns of migration exhibit spatial trends.…”

Section: Discussionmentioning

confidence: 99%

Topography‐Based Particle Image Velocimetry of Braided Channel Initiation

Wang,

Limaye,

Chadwick

2024

Water Resources Research

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River channels shape landscapes through gradual migration and abrupt avulsion. Measuring the motion of braided rivers, which have multiple channel threads, is particularly challenging, limiting predictions for landscape evolution and fluvial architecture. To address this challenge, we extended the capabilities of image‐based particle image velocimetry (PIV)—a technique for tracking channel threads in images of the surface—by adapting it to analyze topographic change. We applied this method in a laboratory experiment where a straight channel set in non‐cohesive sediment evolved into a braided channel under constant water and sediment fluxes. Topography‐based PIV successfully tracked the motion of channel threads if displacements between observations were less than the channel‐thread width, consistent with earlier results from image‐based PIV. We filtered spurious migration vectors with magnitudes less than the elevation grid spacing, or with high uncertainties in magnitude and/or direction. During braided channel initiation, migration rates varied with the channel planform development, showing an increase as incipient meanders developed, a decrease during the transitional braiding phase, and consistently low values during the established braiding phase. In this experimental setup, migration rates varied quasi‐periodically along stream at the half scale of initial meander bends. Lateral migration with respect to the mean flow direction was much more pronounced than streamwise migration, accounting for approximately 80% of all detected motion. Results demonstrate that topography‐based PIV has the potential to advance predictions for bank erosion and landscape evolution in natural braided rivers as well as bar preservation and stratigraphic architecture in geological records.

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Section: Discussionmentioning

confidence: 99%

Topography‐Based Particle Image Velocimetry of Braided Channel Initiation

Wang,

Limaye,

Chadwick

2024

Water Resources Research

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Submarine‐channel meandering reset by landslide filling, Taranaki Basin, New Zealand

Covault,

Sylvester,

Dunlap

2024

The Depositional Record

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Landslides are among the largest mass movements on Earth. As such, the deposits of landslides, also known as mass‐transport deposits, are significant architectural elements of continental margins, especially those receiving sediment from large deltas. Landslide dams have been shown to alter the courses of rivers and submarine channels. However, there are fewer examples of landslides completely filling submarine channels and examples of the subsequent stratigraphic evolution. A three‐dimensional seismic‐reflection dataset (<90 Hz) from the deep‐water (>1500 m) Taranaki Basin, offshore the North Island of New Zealand, was used to explore the response of a sequence of channel deposits to landslide filling. The basal channel system initially meandered like a river, with successive channel positions in close proximity, as it aggraded >250 ms two‐way travel time. This systematic, organised evolution is governed by the memory of early channel evolution, which sets the sea floor geomorphology that guides channel‐forming turbidity currents. Later, a channel approximately twice as wide as underlying channels cut off a number of channel bends, probably as a result of an increase in the discharge of channel‐forming turbidity currents. This last channel was filled with submarine landslides, which transported and deposited sediment as debris flows based on the presence of blocks within a matrix comprising chaotic, lower amplitude seismic facies. These debris‐flow deposits smoothed over the sea floor, effectively wiping the memory of channel evolution. As a result, the subsequent channel pattern bears no resemblance to the basal system. Submarine‐channel resetting by landslide filling is common in settings with frequent catastrophic basin‐margin collapses, like offshore New Zealand.

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