A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides

Samantha L. Clarke, Thomas Hubble, Jody M. Webster, David Airey, Elyssa de Carli, Cristina Ferraz, Paula Reimer, Ron Boyd, John Keene

Research output: Contribution to conferencePoster

Abstract

Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within-slide cores are either: a) erosional features that developed after the occurrence of the landslide in which case the hiatus surface age provides a minimum age for landslide occurrence or b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding in which case the post-hiatus sediment dates indicates approximately when landsliding occurred. In either case, it is reasonable to suggest that these two spatially adjacent slides occurred penecontemporaneously approximately 20,000 years ago.
LanguageEnglish
Publication statusPublished - Dec 2013
EventAGU Fall Meeting 2013 - San Francisco, United States
Duration: 09 Dec 201313 Dec 2013

Conference

ConferenceAGU Fall Meeting 2013
CountryUnited States
CitySan Francisco
Period09/12/201313/12/2013

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submarine landslide
continental slope
hiatus
sediment
landslide
accelerator mass spectrometry
rupture
dating
profiler
accumulation rate
bathymetry
canyon
bulk density
stiffness
slab
silt
mud
seafloor
transect
organic carbon

Bibliographical note

American Geophysical Union, Fall Meeting 2013, abstract #OS11D-1672

Cite this

Clarke, S. L., Hubble, T., Webster, J. M., Airey, D., de Carli, E., Ferraz, C., ... Keene, J. (2013). A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides. Poster session presented at AGU Fall Meeting 2013, San Francisco, United States.
Clarke, Samantha L. ; Hubble, Thomas ; Webster, Jody M. ; Airey, David ; de Carli, Elyssa ; Ferraz, Cristina ; Reimer, Paula ; Boyd, Ron ; Keene, John. / A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides. Poster session presented at AGU Fall Meeting 2013, San Francisco, United States.
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abstract = "Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20{\%}), silt (50-65{\%}) and sand (15-40{\%}) and are generally uniform in appearance. Their carbonate contents vary between and 17{\%} and 22{\%} by weight while organic carbon contents are less than 10{\%} by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within-slide cores are either: a) erosional features that developed after the occurrence of the landslide in which case the hiatus surface age provides a minimum age for landslide occurrence or b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding in which case the post-hiatus sediment dates indicates approximately when landsliding occurred. In either case, it is reasonable to suggest that these two spatially adjacent slides occurred penecontemporaneously approximately 20,000 years ago.",
author = "Clarke, {Samantha L.} and Thomas Hubble and Webster, {Jody M.} and David Airey and {de Carli}, Elyssa and Cristina Ferraz and Paula Reimer and Ron Boyd and John Keene",
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Clarke, SL, Hubble, T, Webster, JM, Airey, D, de Carli, E, Ferraz, C, Reimer, P, Boyd, R & Keene, J 2013, 'A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides' AGU Fall Meeting 2013, San Francisco, United States, 09/12/2013 - 13/12/2013, .

A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides. / Clarke, Samantha L. ; Hubble, Thomas; Webster, Jody M.; Airey, David; de Carli, Elyssa; Ferraz, Cristina; Reimer, Paula; Boyd, Ron; Keene, John.

2013. Poster session presented at AGU Fall Meeting 2013, San Francisco, United States.

Research output: Contribution to conferencePoster

TY - CONF

T1 - A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides

AU - Clarke, Samantha L.

AU - Hubble, Thomas

AU - Webster, Jody M.

AU - Airey, David

AU - de Carli, Elyssa

AU - Ferraz, Cristina

AU - Reimer, Paula

AU - Boyd, Ron

AU - Keene, John

N1 - American Geophysical Union, Fall Meeting 2013, abstract #OS11D-1672

PY - 2013/12

Y1 - 2013/12

N2 - Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within-slide cores are either: a) erosional features that developed after the occurrence of the landslide in which case the hiatus surface age provides a minimum age for landslide occurrence or b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding in which case the post-hiatus sediment dates indicates approximately when landsliding occurred. In either case, it is reasonable to suggest that these two spatially adjacent slides occurred penecontemporaneously approximately 20,000 years ago.

AB - Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within-slide cores are either: a) erosional features that developed after the occurrence of the landslide in which case the hiatus surface age provides a minimum age for landslide occurrence or b) detachment surfaces from which slabs of near-surface sediment were removed during landsliding in which case the post-hiatus sediment dates indicates approximately when landsliding occurred. In either case, it is reasonable to suggest that these two spatially adjacent slides occurred penecontemporaneously approximately 20,000 years ago.

M3 - Poster

ER -

Clarke SL, Hubble T, Webster JM, Airey D, de Carli E, Ferraz C et al. A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides. 2013. Poster session presented at AGU Fall Meeting 2013, San Francisco, United States.