HR: 1340h
AN: U33A-0012    [Abstracts]
TI: Chronological Constraints on Processes Leading to Large Active Landslides Using in Situ 10Be
AU: * Bigot-Cormier, F J
EM: bigot@u.washington.edu
AF: University of Washington Dept Earth & Space Sciences, 310 Condon Hall ƒ_› Box 351310, seattle, WA 98195 United States
AU: Braucher, R
EM: braucher@cerege.fr
AF: CEREGE, Plateau de lƒ_TArbois, BP 80, Aix-en-Provence, 13545 France
AU: Bourles, D
EM: bourles@cerege.fr
AF: CEREGE, Plateau de lƒ_TArbois, BP 80, Aix-en-Provence, 13545 France
AU: Guglielmi, Y
EM: guglielmi@geoazur.unice.fr
AF: GAcosciences Azur, UMR 6526 CNRS/UNSA, 250 rue A. Einstein, Valbonne, 06560 France
AU: Recorbet, F
EM: recorbet@cerege.fr
AF: CEREGE, Plateau de lƒ_TArbois, BP 80, Aix-en-Provence, 13545 France
AU: Dubar, M
EM: dubar@cepam.cnrs.fr
AF: CNRS/CRA, 250 rue A. Einstein, Valbonne, 06560 France
AU: Stephan, J
EM: stephan@geoazur.unice.fr
AF: GAcosciences Azur, UMR 6526 CNRS/UNSA, 250 rue A. Einstein, Valbonne, 06560 France
AB: Cosmic ray exposure dating of gravitational scarps along a slope nesting a presently active landslide (La ClapiŠre landslide, Tin‚e valley, Argentera massif, SE France) reveal successive periods of gravitational destabilization. An initial gravitational destabilization at 10.3±0.5 10Be ka occurs more than 3 000 yr after the end of the last deglaciation of the Tin‚e valley, dated in the studied area from stoss-and-lee topography sampled along the Tin‚e and its tributary Rabuons valleys. A second gravitational destabilization is well constrained at 7.1±0.5 10Be ka through the dating of two gravitational scarps. Although coincidental with the so-called "climatic optimum", other local or regional triggering factors may be invoked. A third evidenced gravitational destabilization occurred 2.3±0.5 10Be ka ago. This study thus demonstrates that in situ produced cosmogenic 10Be allows establishing the chronology of gravitational destabilization leading to present major active landslides. However, in the presented case, deciphering between the various possible triggering factors will necessitate similar studies on other landslides inside the alpine arc: new results from three other areas located in the southern part of the alpine arc will be presented.
DE: 1040 Radiogenic isotope geochemistry
DE: 1105 Quaternary geochronology
DE: 1130 Geomorphological geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 8122 Dynamics: gravity and tectonics
SC: Union [U]
MN: Fall Meeting 2005