Rixhon G., Braucher R., Bourles D. L., Peeters A., Demoulin A., Leanni Laetitia, Aster Team. (2020). Plio-Quaternary landscape evolution in the uplifted Ardennes : new insights from Al-26/Be-10 data from cave-deposited alluvium (Meuse catchment, E. Belgium). Geomorphology, 371, p. 107424 [13 p.]. ISSN 0169-555X.
Titre du document
Plio-Quaternary landscape evolution in the uplifted Ardennes : new insights from Al-26/Be-10 data from cave-deposited alluvium (Meuse catchment, E. Belgium)
Rixhon G., Braucher R., Bourles D. L., Peeters A., Demoulin A., Leanni Laetitia, Aster Team
Source
Geomorphology, 2020,
371, p. 107424 [13 p.] ISSN 0169-555X
Despite a wealth of recent studies dealing with the evolution of the drainage network in the uplifted Ardennes massif (E. Belgium), especially from the Middle Pleistocene onwards, the Ardennian landscape evolution and long-term incision rates in the Meuse catchment remain poorly documented over the whole Plio-Quaternary. Alluvium-filled multilevel cave systems represent a relevant setting to unravel the Late Cenozoic history of re-gional river incision. We present here a dataset of Al-26/Be-10 concentration data obtained from fifteen pebble samples washed into the Chawresse system, one of the largest multi-level cave systems of Belgium, which developed in Devonian limestones of the lower Ourthe Valley, the main Ardennian tributary of the Meuse. The sample collection spans an elevation difference higher than 120 m and their depleted Al-26/Be-10 ratios yield burial ages ranging from-0.25 to 3.28 Ma. After critical assessment of our dataset for intra-karstic reworking issues, the most striking outcome of the obtained burial ages is the acceleration by a factor five of the incision rates (from-30 to-150 m/Ma) during the first half of the Middle Pleistocene. Integrating this incision peak and our pre-burial denudation rates, we then revisit the existing framework of Plio-Quaternary denudation and river incision in the Ardennian Meuse catchment. Whilst our Al-26/Be-10 concentration data shed new light on the temporal and spatial variability of the local river and hillslope system response to coupled tectonic and climatic forcings, it simultaneously highlights sampling issues and the need for further chronological data.
Plan de classement
Hydrologie [062]
;
Géologie et formations superficielles [064]
