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Daily bathymetric surveys document how stratigraphy is built and its extreme incompleteness in submarine channels

Daily bathymetric surveys document how stratigraphy is built and its extreme incompleteness in submarine channels
Daily bathymetric surveys document how stratigraphy is built and its extreme incompleteness in submarine channels

Turbidity currents are powerful flows of sediment that pose a hazard to critical seafloor infrastructure and transport globally important amounts of sediment to the deep sea. Due to challenges of direct monitoring, we typically rely on their deposits to reconstruct past turbidity currents. Understanding these flows is complicated because successive flows can rework or erase previous deposits. Hence, depositional environments dominated by turbidity currents, such as submarine channels, only partially record their deposits. But precisely how incomplete these deposits are, is unclear. Here we use the most extensive repeat bathymetric mapping yet of any turbidity current system, to reveal the stratigraphic evolution of three submarine channels. We re-analyze 93 daily repeat surveys performed over four months at the Squamish submarine delta, British Columbia in 2011, during which time >100 turbidity currents were monitored. Turbidity currents deposit and rework sediments into upstream-migrating bedforms, ensuring low rates of preservation (median 11%), even on the terminal lobes. Large delta-lip collapses (up to 150,000 m 3 ) are relatively well preserved, however, due to their rapidly emplaced volumes, which shield underlying channel deposits from erosion over the surveyed timescale. The biggest gaps in the depositional record relate to infrequent powerful flows that cause significant erosion, particularly at the channel-lobe transition zone where no deposits during our monitoring period are preserved. Our analysis of repeat surveys demonstrates how incomplete the stratigraphy of submarine channels can be, even over just 4 months, and provides a new approach to better understand how the stratigraphic record is built and preserved in a wider range of marine settings.

channel-lobe transition zone, crescentic bedform, stratigraphic completeness, submarine channel, submarine landslide, turbidity current
0012-821X
231-247
Vendettuoli, D.
16879a32-0874-4edf-a368-52ec101c8967
Clare, M. A.
b26da858-9c08-4784-aaa9-7092efcd94bd
Hughes Clarke, J. E.
81b97b31-58a8-474e-b693-c4f20a54d992
Vellinga, A.
9957dfd4-70a8-4327-b66c-af7f718a0e75
Hizzet, J.
e653991a-457e-4bd7-b261-f0539d736f34
Hage, S.
a914d294-89b9-4686-94f3-e3d7b0c41d76
Cartigny, M. J.B.
d252d7b1-16c6-47b1-bf86-8087070934ce
Talling, P. J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Waltham, D.
fcff468c-e614-4188-95dd-84f158bbbec8
Hubbard, S. M.
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Stacey, C.
36936140-b618-47d1-9d32-76060722ab05
Lintern, D. G.
107a4f6b-6da4-458e-a4be-dcf2a41714d1
Vendettuoli, D.
16879a32-0874-4edf-a368-52ec101c8967
Clare, M. A.
b26da858-9c08-4784-aaa9-7092efcd94bd
Hughes Clarke, J. E.
81b97b31-58a8-474e-b693-c4f20a54d992
Vellinga, A.
9957dfd4-70a8-4327-b66c-af7f718a0e75
Hizzet, J.
e653991a-457e-4bd7-b261-f0539d736f34
Hage, S.
a914d294-89b9-4686-94f3-e3d7b0c41d76
Cartigny, M. J.B.
d252d7b1-16c6-47b1-bf86-8087070934ce
Talling, P. J.
1cbac5ec-a9f8-4868-94fe-6203f30b47cf
Waltham, D.
fcff468c-e614-4188-95dd-84f158bbbec8
Hubbard, S. M.
4f1ecf26-20e6-496c-87dd-8fcd29b0a47e
Stacey, C.
36936140-b618-47d1-9d32-76060722ab05
Lintern, D. G.
107a4f6b-6da4-458e-a4be-dcf2a41714d1

Vendettuoli, D., Clare, M. A., Hughes Clarke, J. E., Vellinga, A., Hizzet, J., Hage, S., Cartigny, M. J.B., Talling, P. J., Waltham, D., Hubbard, S. M., Stacey, C. and Lintern, D. G. (2019) Daily bathymetric surveys document how stratigraphy is built and its extreme incompleteness in submarine channels. Earth and Planetary Science Letters, 515, 231-247. (doi:10.1016/j.epsl.2019.03.033).

Record type: Article

Abstract

Turbidity currents are powerful flows of sediment that pose a hazard to critical seafloor infrastructure and transport globally important amounts of sediment to the deep sea. Due to challenges of direct monitoring, we typically rely on their deposits to reconstruct past turbidity currents. Understanding these flows is complicated because successive flows can rework or erase previous deposits. Hence, depositional environments dominated by turbidity currents, such as submarine channels, only partially record their deposits. But precisely how incomplete these deposits are, is unclear. Here we use the most extensive repeat bathymetric mapping yet of any turbidity current system, to reveal the stratigraphic evolution of three submarine channels. We re-analyze 93 daily repeat surveys performed over four months at the Squamish submarine delta, British Columbia in 2011, during which time >100 turbidity currents were monitored. Turbidity currents deposit and rework sediments into upstream-migrating bedforms, ensuring low rates of preservation (median 11%), even on the terminal lobes. Large delta-lip collapses (up to 150,000 m 3 ) are relatively well preserved, however, due to their rapidly emplaced volumes, which shield underlying channel deposits from erosion over the surveyed timescale. The biggest gaps in the depositional record relate to infrequent powerful flows that cause significant erosion, particularly at the channel-lobe transition zone where no deposits during our monitoring period are preserved. Our analysis of repeat surveys demonstrates how incomplete the stratigraphy of submarine channels can be, even over just 4 months, and provides a new approach to better understand how the stratigraphic record is built and preserved in a wider range of marine settings.

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Accepted/In Press date: 23 March 2019
e-pub ahead of print date: 4 April 2019
Published date: 1 June 2019
Keywords: channel-lobe transition zone, crescentic bedform, stratigraphic completeness, submarine channel, submarine landslide, turbidity current

Identifiers

Local EPrints ID: 430078
URI: https://eprints.soton.ac.uk/id/eprint/430078
ISSN: 0012-821X
PURE UUID: cfbc27bb-01da-4841-afeb-82a40019d49b

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Date deposited: 11 Apr 2019 16:30
Last modified: 09 Dec 2019 17:39

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Contributors

Author: D. Vendettuoli
Author: M. A. Clare
Author: J. E. Hughes Clarke
Author: A. Vellinga
Author: J. Hizzet
Author: S. Hage
Author: M. J.B. Cartigny
Author: P. J. Talling
Author: D. Waltham
Author: S. M. Hubbard
Author: C. Stacey
Author: D. G. Lintern

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