Glacier ice in rock glaciers: a case study in the Vanoise Massif, Northern French Alps
S. Monnier1,*, C. Camerlynck2, F. Rejiba2, C. Kinnard1, and P.-Y. Galibert21Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Campus Andrés Bello, Casilla 554, Raúl Bitrán s/n, La Serena, Chile 2UMR 7619 Sisyphe, Université Pierre et Marie Curie-Paris 6, 4 place Jussieu, 75252 Paris Cedex 05, France *formerly at: UMR 8591 Laboratoire de Géographie Physique (LGP), CNRS-Bellevue Campus, 1 place Aristide Briand, 92195 Meudon Cedex, France
Received: 02 Nov 2011 – Accepted for review: 13 Dec 2011 – Discussion started: 21 Dec 2011
Abstract. We investigated the Sachette rock glacier, Vanoise Massif, Northern French Alps, using former equilibrium line altitude reconstruction from glacial deposits, aerial photograph analysis, and ground-penetrating radar (GPR). The rock glacier is a young (probably <6000 yr) and active landform. The GPR survey consisted of two CMP measurements and four constant-offset profiles. From CMP measurements, the radar wave velocity in exposed shallow massive ice is 0.165–0.17 m ns−1. The constant-offset GPR data was processed and analysed in order to reconstruct the stratigraphy and model the radar wave velocity in two dimensions. The integration of the morphology, the velocity models, and the stratigraphy emphasized, in the upper half of the rock glacier, the good correspondence between high radar wave velocities (>0.15–0.16 m ns−1) and reflectors having a dipping-syncline structure, typical of true glaciers. Consequently, the rock glacier structure is described as being constituted of a glacial massive ice core embedded into diamictons. Our study of the Sachette rock glacier highlights possible significance of rock glaciers and interactions between glacier and permafrost in alpine environments.
Monnier, S., Camerlynck, C., Rejiba, F., Kinnard, C., and Galibert, P.-Y.: Glacier ice in rock glaciers: a case study in the Vanoise Massif, Northern French Alps, The Cryosphere Discuss., 5, 3597-3626, doi:10.5194/tcd-5-3597-2011, 2011.