Interactions between rock avalanches and glaciers in the Mont Blanc massif during the late Holocene |
| |
| Authors: | Philip Deline |
| |
| Institution: | 1. Department of Geodynamics and Geophysics, Steinmann Institute, University of Bonn, Meckenheimer Allee 176, D-53115, Bonn, Germany;2. School of Science, Kathmandu University, P. O. Box: 6250, Kathmandu, Nepal;1. INSTAAR and Department of Geological Sciences, University of Colorado Boulder, Boulder, CO 80309, USA;2. Department of Earth Sciences, Simon Fraser University, 8888 University Dr., Burnaby, B.C. V5A 1S6, Canada;3. Earth Lab, University of Colorado Boulder, Boulder, CO 80309, USA;4. Department of Geological and Environmental Sciences, Appalachian State University, Boone, NC 28607, USA;1. Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland;2. University of Utah, Department of Geology and Geophysics, 115 South 1460 East, Salt Lake City, UT, USA;3. Laboratory of Ion Beam Physics, ETH Zurich, Otto-Stern-Weg 5, 8093 Zurich, Switzerland;4. Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland |
| |
| Abstract: | Rock avalanches are common in the Mont Blanc massif, which is bordered by valleys with large resident and tourist populations and important highways. This paper combines historical data with detailed geomorphological mapping, stratigraphic observation, and absolute and relative dating, to interpret several deposits resulting from rock avalanching onto glaciers.Nineteen rock falls and rock avalanches are described, ranging in volume from 10,000 m3 to 10 × 106 m3. They occurred between 2500 BP and AD 2007 at six sites. The events at three sites (Miage and Drus Glaciers, and Tour des Grandes Jorasses) are characterised by short travel distances; those at Brenva, Triolet, and Frébouge Glaciers exhibit excessive travel distances.Interactions between rock avalanches and glaciers are of four types: (i) rock-avalanche triggering, where glacial and paraglacial controls include debuttressing of rockwalls due to glacier thinning and retreat, oversteepening of rock slopes by glacial erosion, and effects of glaciers on permafrost; (ii) rock-avalanche mobility, in which mobility and travel distance are modified by channelling of rock-avalanche debris by moraines and valleys, incorporation of ice and snow (often >50% for large events), and irregularities on the glacier surface; (iii) deposit sedimentology, where melting of incorporated ice transforms the final deposit by reducing its thickness typically to <5 m, and debris of variable thicknesses is juxtaposed in a hummocky deposit with chaotic piles of angular rock debris; and (iv) glacier dynamics where insulating debris deposited upon a glacier produces a debris-covered glacier of different dynamics, and high elevated scars can favour the formation of small glaciers. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
