Depositional Characteristics of a Submarine Debris Flow

Glacimarine processes affect about 20% of the global ocean today, and this area expanded considerably under cyclical full-glacial conditions during the Quaternary (Fig. 1) . Many of the submarine landforms produced at the base and margin of past ice sheets remain well preserved on the seafloor in fjords and on high-latitude continental shelves after the retreat of the ice that produced them. These glacial landforms, protected from subaerial erosion and beneath wave-base and tidal currents in water that is often hundreds of metres deep, are gradually buried by both hemipelagic and glacimarine sedimentation; they may be preserved over long periods in the geological record if palaeocontinental shelves are not reworked by subsequent glacier advances or bottom currents ). This means that, first, submarine glacial landforms can be observed at or close to the modern seafloor after retreat of the last great ice sheets from their most recent Quaternary maximum about 18-20 000 years ago using swath-bathymetric mapping systems and, secondly, buried glacial landforms may also be identified and examined within glacial-sedimentary sequences from Quaternary and earlier ice ages using seismic-reflection methods.The development of multibeam echo sounding over the past two decades, coupled with high-accuracy GPS positioning, has allowed morphological mapping of the seafloor at an unprecedented level of detail. In this paper, the variety of submarine glacial landforms observed in modern, Quaternary and more ancient sediments is described. Landforms produced subglacially, those formed at and beyond marine ice-sheet margins, together with the slope processes and bottom currents likely to result in their reworking, are considered along with the sediment volumes of these landforms and the time they take to develop. This is followed by discussion of the significance of submarine glacial landforms and landform-assemblages for reconstruction of the form and flow of past ice sheets, including the former extent and flow direction of ice sheets, whether they are flowing fast as ice streams or slowly in inter-ice stream areas, the nature and rate of ice-sheet deglaciation, conditions at past ice-sheet beds, and inferences on the characteristics of the basal hydrological system and past climatic conditions.

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“…A number of mass-wasting processes contribute to downslope sediment transfer on such deltas (e.g. Prior et al 1984).…”

Section: Ice-marginal Landforms: Sedimentary Fansmentioning

confidence: 99%

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

Dowdeswell

Canals

Jakobsson

et al. 2016

Memoirs

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“…Sletten et al 2003), rockfalls (Lemcke 1992;Blikra et al in press;Bussmann 2006) and shore collapses (e.g. Heim 1876Heim , 1888Heim , 1932Kelts & Hsü 1980;Prior et al 1984;Hsü & Kelts 1985;Siegenthaler & Sturm, 1991a, 1991bLongva et. al 2003).…”

Section: Introductionmentioning

confidence: 99%

15,000 Years of mass-movement history in Lake Lucerne: Implications for seismic and tsunami hazards

Schnellmann

Anselmetti

Giardini

et al. 2006

Eclogae geol. Helv.

131

178

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A chronological catalogue of Late Glacial and Holocene mass-movement deposits in Chrüztrichter and Vitznau Basins of Lake Lucerne (Vierwaldstät-tersee) reveals a complex history of natural hazards affecting the lake and its shores. Ninety-one mass-flow and six megaturbidite deposits have been identified and mapped out with a grid of more than 300 km high-resolution seismic profiles. An age model based on the analyses of 10 long piston cores, 2 tephra layers and 32 AMS-14 C ages allowed building up a chronological event catalogue covering the last 15,000 years. Most of the identified mass-flow deposits relate to subaqueous sliding and subaerial rockfalling, as indicated by slide scars and rockfall cones on the lake floor. Deposits related to subaqueous sliding occur at the toe of slopes with inclinations >10°and reach their largest extents below slopes with inclinations between 10 and 20°. On subaqueous slopes >25°there is hardly any sediment accumulation. Rockfall cones and related mass-flow deposits in the northeastern and southern part of Vitznau basin evidence repeated rockfall activity, particularly along two zones on the northern face of Bürgenstock Mountain. Historic examples indicate that such rockfalls, as well as large subaqueous slides, can induce considerable tsunami waves in the lake. All of the 91 identified mass-flow deposits are associated with 19 seismic-stratigraphic event horizons. One of them comprises 13 mass-flow deposits and 2 megaturbidites and relates to the 1601 A.D. Mw~ 6.2 earthquake. By analogy, five older multiple mass-movement horizons, each including six or more coeval deposits, are interpreted to result from strong prehistoric earthquakes.

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“…anatomy of MTCs later observed by others (Prior et al, 1984;Martinsen, 1994;Frey Martinez et al, 2005). He recognized the systematic distribution of strain exhibited in several MTCs offshore New Zealand; with extensional structures characterizing the upslope region, relatively undeformed strata in the middle region, and compressional structures dominating the downslope region (Figure 1.3).…”

Section: Architecture Of Mtcs and Implications For Seal Potentialmentioning

confidence: 87%

Fabric Development and Pore-Throat Reduction in a Mass-Transport Deposit in the Jubilee Gas Field, Eastern Gulf of Mexico: Consequences for the Sealing Capacity of MTDs

Cardona

Wood

Day-Stirrat

et al. 2016

Advances in Natural and Technological Hazards Research

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Depositional Characteristics of a Submarine Debris Flow

Cited by 239 publications

References 7 publications

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

The variety and distribution of submarine glacial landforms and implications for ice-sheet reconstruction

15,000 Years of mass-movement history in Lake Lucerne: Implications for seismic and tsunami hazards

Fabric Development and Pore-Throat Reduction in a Mass-Transport Deposit in the Jubilee Gas Field, Eastern Gulf of Mexico: Consequences for the Sealing Capacity of MTDs

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