Catastrophic Debris-Flow Deposits from an Inferred Landslide-Dam Failure, Eocene Berga Formation, Eastern Pyrenees, Spain

  1. I. Peter Martini4,
  2. Victor R. Baker5 and
  3. Guillermina Garzón6
  1. E. Saula1,
  2. E. Emili Mato1 and
  3. C. Puigdefabregas2,3

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304299.ch11

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

Flood and Megaflood Processes and Deposits: Recent and Ancient Examples

How to Cite

Saula, E., Mato, E. E. and Puigdefabregas, C. (2009) Catastrophic Debris-Flow Deposits from an Inferred Landslide-Dam Failure, Eocene Berga Formation, Eastern Pyrenees, Spain, in Flood and Megaflood Processes and Deposits: Recent and Ancient Examples (eds I. P. Martini, V. R. Baker and G. Garzón), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304299.ch11

Editor Information

  1. 4

    Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada

  2. 5

    Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721–0011, USA

  3. 6

    Dpto de Geodinámica, Fac. de Geología, Universidad of Complutense, 28040 Madrid, Spain

Author Information

  1. 1

    Institut Cartogràfic de Catalunya, Parc de Montjuic, E-08038 Barcelona, Spain

  2. 2

    Institut de Ciències de la Terra (CSIC), Carrer Lluis Solé Sabarís, E-0828 Barcelona/Norsk, Spain

  3. 3

    Hydro Research Centre, N-5020 Bergen, Norway

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 10 FEB 2002

ISBN Information

Print ISBN: 9780632064045

Online ISBN: 9781444304299

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Keywords:

  • catastrophic debris-flow deposits from inferred landslide-dam failure - Eocene Berga formation, eastern Pyrenees, Spain;
  • regional setting and general characteristics of Berga formation;
  • general features of pedret bed;
  • facies and architecture of Pedret Bed;
  • flow characteristics;
  • flow generation

Summary

The Berga Alluvial Fan System (Upper Eocene to Oligocene) has developed at the northern active margin of the South Pyrenean Foreland Basin. A number of individual debris-flow conglomerate beds have been identified within the otherwise stream-flood-dominated fan system. One of these, the Pedret Bed, has been mapped throughout the area. It is characterized by a monomictic Mesozoic limestone clast composition that contrasts with the polymictic composition of the host alluvial fan sequence, by a remarkable clast angularity, and by its great lateral extent of about 146 km2. A well-defined pattern of sediment distribution within the Pedret Bed mirrors the inner, mid and outer fan facies belts of the host alluvial fan sequence. The Pedret Bed, 8 m thick at most, includes four distinctly mappable successive units, which seem to correspond to different flow events.

The bulk of the Pedret Bed was deposited mainly from debris-flow processes. The resulting sequences show some of the characteristics of subaqueous debris flows, although as inferred from regional evidence, subaqueous deposition of the Pedret Bed seems highly unlikely. The breccia-like texture, the contrasting locally derived clast composition, the great lateral extent, and the mass-flow origin suggest that the flows depositing the estimated 266 × 106 m3 of sediment of the Pedret Bed originated from a landslide-dam failure within the drainage basin. Such a process, involving large amounts of sediment but also large amounts of water, would account for the similarities of these deposits with those resulting from subaqueous debris flows.

Debris flows generated from landslide-dam failure may constitute an ordinary process in alluvial-fan systems at the geological scale, and may be an important process accounting for the deposition of large volumes of sediment in alluvial fans.