Gloria Knolls Slide: a prominent submarine landslide complex on the Great Barrier Reef margin of north-eastern Australia

ANGEL PUGA-BERNABEU, Robin J. Beaman, Jody M. Webster, Alexander Thomas, Geraldine Jacobsen

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We investigate the largest submarine landslide, the Gloria Knolls Slide (GKS), on the Great Barrier Reef margin of north-eastern Australia, the largest extant mixed carbonate-siliciclastic province in the world. Based on the most complete high-resolution bathymetric and sub-bottom profile datasets available for the region, we describe the main surface and subsurface geomorphologic characteristics of the GKS. The GKS forms a 20 km along-slope and 8 km across-slope indentation in the margin, extending from 250 to 1350 m depth, and involves a volume of sediment of 32 km3. Three main seafloor terrains can be distinguished based on seafloor morphology: a source area, a proximal depositional area and a distal depositional area. The source area includes a main headwall scarp with a maximum height of 830 m and a secondary scarp at 670 m depth with a drop of 400 m. The proximal depositional area is flat and smooth, extends up to 14 km across from the toe of the main headwall scarp, and lacks debris exposed on the seafloor. The distal depositional area has a hummocky surface showing a distinctive cluster of eight knolls (up to 3.6 km long and 179 m in height) and over 70 small (up to 15 m high and 500 m wide) debris blocks. In the sub-bottom profiles, the GKS is identified below the background sediment drape as a partially confined, wedge-shaped body of mostly weak amplitude, transparent reflectors in the proximal depositional area; and more discontinuous and chaotic in the distal depositional area. The failed sediment slab of the GKS was evacuated, transported and disintegrated downslope following a sequential failure process spreading successively from the lower slope to the upper slope. The timing of emplacement of the GKS, constrained by radiometric age of fossil biota from the surface of the largest slide block, was at least before 302 ka. The GKS occurred in a slope region dissected by a set of landslides whose scarps are located at similar depths as that of the secondary GKS scarp. The presence of alternating mixed carbonate and siliciclastic lithologies that build the slope might have played an important role as a preconditioning factor in this region. Preliminary calculations suggest that an unexpectedly large seismic event was the most likely triggering mechanism for the GKS. This work contributes to the understanding of large mass-movement deposits in mixed carbonate-siliciclastic margins and provides a useful morphologic characterization and evolutionary model for assessing its tsunamigenic potential with further numerical simulations.
Original languageEnglish
Pages (from-to)68-83
JournalMarine geology
Early online date27 Dec 2016
Publication statusPublished - 1 Mar 2017


  • Mass transport deposits
  • Tsunamigenic potential
  • Cold-water coral
  • Great Barrier Reef
  • Continental slope
  • Slope failures


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