Chronological constrain of la clapiere landslide ( 44°15 n, 6° 56 e, france) : geomorphology and cosmonuclide approaches.
Abstract
The major La Clapière landslide, located in the Tinée valley (Crystalline massif of Argentera, SE France), comprised two well distinguished parts : from 1,100 to 1,800 m, an historical and instrumented landslide (rock volume on the order of 50 10^6 m^3) that is included in an older biggest landslide evidenced, from 1,800 to 2,200 m, by gravitational fault scarps and crevasses. The aim of the presented study, which is part of a more global French program on gravity destabilization events, is to constrain the initiation time of the oldest landslide. It may indeed have been induced either by an isostatic rebound after the glaciers retreat (i.e. after ∼22ky), or by an older destabilization linked to the high denudation rate evidenced by apatite fission tracks after 3.5 Myr. In order to address these questions, measurement by Accelerator Mass Spectrometry of the in situ-produced cosmogenic 10Be concentration of 24 samples will be undertaken. Five roches moutonnées sampled at various altitudes will be processed in order to constrain the glacier retreat in the Tinée valley. The other samples (mainly part of vertical profiles) from gravitational fault scarps, crevasses and relics surfaces will be used to date the initiation of the destabilization process and to estimate the mean local erosion rate. Moreover, analysis of some quaternary paleo-surfaces on both sides of the valley was also undertaken to establish within the chronological framework the relative importance of gravity destabilization and old tectonic movements on the structuration of the valley side affected by the landslides.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....12840B