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Shelf-to-canyon sediment supply mechanisms in the Gulf of Lions and Eel margins

Shelf-to-canyon sediment supply mechanisms in the Gulf of Lions and Eel margins. Pere Puig. Institut de Ciències del Mar, CSIC With contributions from:. ICM-CSIC: Albert Palanques, Jorge Guillén, Jacobo Martín, Marta Ribó UB: Antoni Calafat, Joan Fabrés, Miquel Canals

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Shelf-to-canyon sediment supply mechanisms in the Gulf of Lions and Eel margins

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  1. Shelf-to-canyon sediment supply mechanisms in the Gulf of Lions and Eel margins Pere Puig Institut de Ciències del Mar, CSIC With contributions from: ICM-CSIC: Albert Palanques, Jorge Guillén, Jacobo Martín, Marta Ribó UB: Antoni Calafat, Joan Fabrés, Miquel Canals CEFREM: Xavier Durrieu de Madron, Serge Heussner UW: Andrea Ogston, Beth Mullenbach, Chuck Nittrouer, Dick Sternberg

  2. Gulf of Lions Mistral Wind Tramontane Wind Llevant Wind

  3. Winter 2004 Winter 2005 • Along-margin • Shelf-to-canyon EuroSTRATAFORM monitoring efforts

  4. Winter 2004 Winter 2005 Wave-storms & floods Continuous northerly winds Forcing conditions 4 Dec 21 Feb

  5. Canyon heads (winter 2004) 4 Dec 21 Feb

  6. Canyon heads (winter 2004) > 68 mg/l 4 Dec 21 Feb

  7. Net fluxes (mg/m2s) Canyon heads (winter 2004) 29 7 11 321 12 10 5 Swath bathymetry conducted by Ifremer

  8. 145 m 200 m 500 m 750 m Cap de Creus Canyon (winter 2005) Upper canyon monitoring Swath bathymetry conducted by AOA, Fugro and UB

  9. Cap de Creus Canyon (winter 2005) Temperature (ºC) Current speed (cm/s)

  10. Cap de Creus Canyon (winter 2005) SSC (mg/l) Cumulative flux (Tm/m2) (1 mab)

  11. Winter 2006 Winter 2007- Present • Across-margin • Canyon head monitoring HERMES & HERMIONE monitoring efforts Rhone River See Palanques et al. poster M-25

  12. Time series (1) 140 mg/l 175 mg/l > 68 mg/l

  13. Time series (2) 140 mg/l 175 mg/l > 68 mg/l 0.4 2.9 7.1 7.3 2.7

  14. February 2007 Storm resuspension & cascading advection (1)

  15. January 2008 Storm resuspension & cascading advection (2)

  16. S 60 Eel margin

  17. Shelf (S 60) time series 28 Oct ~ 8 g/l

  18. Eel Canyon time series 28 Oct 108 mg/l

  19. Storm resuspension at the canyon head

  20. Storm-induced sediment gravity flows (1)

  21. Storm-induced sediment gravity flows (2)

  22. Wave-supported sediment gravity flows

  23. Liquefaction by excess pore water pressure P0 0 Pressure 0 WAVE INFILTRATION PRESSURES ZONE A Highly disturbed, liquefied, transportable SHEAR INDUCED EXCESS PORE WATER PRESSURE Penetration below seafloor ZONE B Non liquefiable Added stress may induce failure LIQUEFACTION CRITERIA ZONE C Pore water pressures from wave infiltration ZONE D No pore pressure response From: Clukey et al. 1985. Geo-Marine Letters, 5: 177-183

  24. Conclusions • Contemporary shelf-to-canyon sediment supply in the studied margin is controlled by event-driven transport processes. • Wave-storm resuspension events concurrent with dense shelf water cascading are the major contemporary shelf-to-canyon sediment transport mechanisms in the Gulf of Lions margin, while deep cascading events contribute to redistribute the sediment deposited in canyon head regions down to deeper parts of the margin (see Palanques et al. poster M-25). • Wave-storm events are also the main shelf-to-canyon sediment transport process in the Eel margin, but the supply mechanism is controlled by wave-load sediment liquefaction at the shelf edge and upper canyon head regions.

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