Lacustrine turbidites produced by surficial slope sediment remobilization: A mechanism for continuous and sensitive turbidite paleoseismic records
Lacustrine turbidites produced by surficial slope sediment remobilization: A mechanism for continuous and sensitive turbidite paleoseismic records
Turbidite records along ocean margins and in lake basins are increasingly used as paleoseismic proxies. However, the slope remobilization processes that formed the earthquake-related turbidity currents are poorly understood and, therefore, it is difficult to assess the consistency of turbidite paleoseismic records. We analyzed the sedimentary imprint of the giant AD 1960 (Mw 9.5) Chile earthquake in four South-Central Chilean lakes. Mass-transport deposits and turbidites were compared by interpreting reflection-seismic profiles, sedimentary facies, volume balances and proxies for turbidite composition (i.e. grain size, radionuclides, sediment color, organic matter). Sediment lightness was used as a proxy for organic matter content. Comparison of lightness of turbidites and the underlying sediments shows that earthquake-triggered turbidites in the four lakes result from remobilization of a thin veneer (on average about 5 cm) of slope sediments and do not result from disintegration of subaquatic landslides. Statistical analysis of 34 turbidites in a new 5200 year sedimentary record does not show any correlation between inter-event time and turbidite thickness (and thus volume). This means that inter-event slope recharging is not a dominant factor governing turbidite recurrence and that initiation of turbidity currents by remobilization of surficial sediments is different to slope failure related to subaquatic landslides. We conclude that surficial slope sediment remobilization forms a valid mechanism that explains why turbidite paleoseismic records can be of excellent continuity and high sensitivity. Moreover, based on correlations between seismic intensity, turbidite volume and stratigraphic remobilization depth, we propose that surficial slope sediment remobilization allows for turbidite records containing information about paleo-earthquake intensity.
Turbidite paleoseismology, Sediment remobilization, South-Central Chile, Subaquatic landslide, Limnogeology
159-176
Moernaut, Jasper
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Van Daele, Maarten
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Strasser, Michael
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Clare, Michael A.
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Heirman, Katrien
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Viel, Matías
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Cardenas, Javiera
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Kilian, Rolf
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Ladrón de Guevara, Bruno
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Pino, Mario
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Urrutia, Roberto
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De Batist, Marc
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1 February 2017
Moernaut, Jasper
7ab37f3f-8b30-4ab0-babd-39f71ab392a7
Van Daele, Maarten
6aea1fe6-fd49-44e6-bf5e-31833a6220f8
Strasser, Michael
5e3e2a3b-b03b-42dd-8557-3a259422fb58
Clare, Michael A.
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Heirman, Katrien
76db932e-ad85-44c8-aa1d-08078f2b821c
Viel, Matías
052c60bf-7216-48aa-b04d-316e2c54a62a
Cardenas, Javiera
b821e79c-f69d-4cbb-b230-9121f18a8b6f
Kilian, Rolf
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Ladrón de Guevara, Bruno
29307f55-0ca0-40eb-8939-eade451ce0f6
Pino, Mario
5b748e89-6f75-4382-ad89-c97440bb7c64
Urrutia, Roberto
b87b8843-b7f5-4da5-8155-424f828dba6c
De Batist, Marc
c4d103c4-2ba7-46fe-ac7f-fa9e62949537
Moernaut, Jasper, Van Daele, Maarten, Strasser, Michael, Clare, Michael A., Heirman, Katrien, Viel, Matías, Cardenas, Javiera, Kilian, Rolf, Ladrón de Guevara, Bruno, Pino, Mario, Urrutia, Roberto and De Batist, Marc
(2017)
Lacustrine turbidites produced by surficial slope sediment remobilization: A mechanism for continuous and sensitive turbidite paleoseismic records.
Marine Geology, 384, .
(doi:10.1016/j.margeo.2015.10.009).
Abstract
Turbidite records along ocean margins and in lake basins are increasingly used as paleoseismic proxies. However, the slope remobilization processes that formed the earthquake-related turbidity currents are poorly understood and, therefore, it is difficult to assess the consistency of turbidite paleoseismic records. We analyzed the sedimentary imprint of the giant AD 1960 (Mw 9.5) Chile earthquake in four South-Central Chilean lakes. Mass-transport deposits and turbidites were compared by interpreting reflection-seismic profiles, sedimentary facies, volume balances and proxies for turbidite composition (i.e. grain size, radionuclides, sediment color, organic matter). Sediment lightness was used as a proxy for organic matter content. Comparison of lightness of turbidites and the underlying sediments shows that earthquake-triggered turbidites in the four lakes result from remobilization of a thin veneer (on average about 5 cm) of slope sediments and do not result from disintegration of subaquatic landslides. Statistical analysis of 34 turbidites in a new 5200 year sedimentary record does not show any correlation between inter-event time and turbidite thickness (and thus volume). This means that inter-event slope recharging is not a dominant factor governing turbidite recurrence and that initiation of turbidity currents by remobilization of surficial sediments is different to slope failure related to subaquatic landslides. We conclude that surficial slope sediment remobilization forms a valid mechanism that explains why turbidite paleoseismic records can be of excellent continuity and high sensitivity. Moreover, based on correlations between seismic intensity, turbidite volume and stratigraphic remobilization depth, we propose that surficial slope sediment remobilization allows for turbidite records containing information about paleo-earthquake intensity.
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More information
Accepted/In Press date: October 2015
Published date: 1 February 2017
Keywords:
Turbidite paleoseismology, Sediment remobilization, South-Central Chile, Subaquatic landslide, Limnogeology
Organisations:
Marine Geoscience
Identifiers
Local EPrints ID: 387255
URI: http://eprints.soton.ac.uk/id/eprint/387255
ISSN: 0025-3227
PURE UUID: 9b7d7c02-f0dc-4c96-a0de-b1380fa283ba
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Date deposited: 11 Feb 2016 16:25
Last modified: 14 Mar 2024 22:46
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Contributors
Author:
Jasper Moernaut
Author:
Maarten Van Daele
Author:
Michael Strasser
Author:
Michael A. Clare
Author:
Katrien Heirman
Author:
Matías Viel
Author:
Javiera Cardenas
Author:
Rolf Kilian
Author:
Bruno Ladrón de Guevara
Author:
Mario Pino
Author:
Roberto Urrutia
Author:
Marc De Batist
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