HR: 17:30h
AN: T14C-07    [Abstracts]
TI: Tectonic vs. climatic controls on accelerated Mio-Pliocene denudation of the Western European Alps
AU: Vernon, A
EM: Antoine.Vernon@ed.ac.uk
AF: School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh, EH9-3JW, United Kingdom
AU: Vernon, A
EM: Antoine.Vernon@ed.ac.uk
AF: LGCA, Universite Joseph Fourier, BP 53, Grenoble, 38041, France
AU: * van der Beek, P
EM: pvdbeek@ujf-grenoble.fr
AF: LGCA, Universite Joseph Fourier, BP 53, Grenoble, 38041, France
AU: Sinclair, H
EM: hugh.sinclair@glg.ed.ac.uk
AF: School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh, EH9-3JW, United Kingdom
AU: Rahn, M
EM: Meinert.Rahn@hsk.ch
AF: Swiss Federal Nuclear Safety Inspectorate, HSK, Villigen, 5232, Switzerland
AB: A sharp increase in deposited sediment volume since Pliocene times has been observed worldwide (Zhang et al., Nature 2001) and in particular around the European Alps (Kuhlemann et al., Int. J. Earth Sci. 2002). The phenomenon has been linked to a rise in denudation rates controlled by an increase of either climatic or tectonic forcing. We exploit the unique density of apatite fission-track ages in the Western European Alps to reconstruct cooling isoage surfaces and to estimate exhumation rates between 14 and 2 Ma. Our methodical approach is based on the association of isoage contours with age-elevation relationships. We use map-view interpolation, enabling a spatio-temporal analysis of exhumation rates over the entire Western Alps. Exhumation histories were reconstructed for eight areas of the Western Alps and display strong similarities in timing and rates with orogen- wide average denudation rates inferred from sediment volumes. This consistency validates the use of both techniques for the study of an orogen characterised by strong relief and high recent exhumation rates. We conclude that exhumation rates in the Western Alps have increased more than twofold during the Pliocene. Our spatialisation of inferred denudation rates through time allows us to study possible controls on these by spatial correlation with morphological (e.g., relief, mean elevation, unit stream power), tectonic (current strain rates, seismic energy released) and climatic (precipitation, LGM ice thickness) forcing variables. Whereas clear correlations exist between long-term exhumation rates and both morphologic variables and geodetically determined present-day rock uplift, the controls exerted by either tectonic or climatic forcing on the spatial distribution of exhumation appear more subtle.
DE: 1140 Thermochronology
DE: 1815 Erosion
DE: 8038 Regional crustal structure
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8175 Tectonics and landscape evolution
SC: Tectonophysics [T]
MN: 2007 Fall Meeting