Chronological Constraints on Processes Leading to Large Active Landslides Using in Situ 10Be
Abstract
Cosmic ray exposure dating of gravitational scarps along a slope nesting a presently active landslide (La Clapiere landslide, Tinee 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 Tinee valley, dated in the studied area from stoss-and-lee topography sampled along the Tinee 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.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.U33A0012B
- Keywords:
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- 1040 Radiogenic isotope geochemistry;
- 1105 Quaternary geochronology;
- 1130 Geomorphological geochronology;
- 1150 Cosmogenic-nuclide exposure dating (4918);
- 8122 Dynamics: gravity and tectonics