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Accueil du site > Français > Les annonces de séminaires et thèses > Séminaire de Philippe STEER (Bergen University, Norway)

Séminaire de Philippe STEER (Bergen University, Norway)

Date : 3 février 2012, 11 h

Titre : Recent glacial erosion of fjords and low-relief surfaces in western Scandinavia. (séminaire en français)

Lieu : Salle B. Auvray (Bât. 15, RdC)

Résumé :

Although glacial landscapes are characterized by dramatic local relief, they also ubiquitously exhibit high-elevation low-relief surfaces. While these surfaces have been attributed to glacial headward erosion in Alpine settings, the timing and processes responsible for their formation in northern high-latitude regions remain elusive. Here, we investigate the topographic evolution of western Scandinavia during the Late Pliocene and Quaternary glaciations (0-2.8 Myr) by comparing inland erosion and offshore sedimentation. Fjord erosion over the entire western Scandinavia, quantified using the geophysical relief, only accounts for 30-55 % of the total sediment volume deposited offshore Norway. This large mismatch implies that significant erosion must have taken place at high elevation during this period, despite the conspicuous nature of the fjords. Furthermore, comparing the distribution of the low-relief surfaces with Equilibrium Line Altitudes (ELAs) suggests a glacial “buzzsaw†mechanism for their formation. In turn, by reconciling glacial erosion of fjords and topography around/above the ELA, our results clearly illustrate how glacial erosion can simultaneously increase topographic relief and still limit mountain height. We suggest that similar processes may have created similar morphologies in other northern high-latitude landscapes, and that models of their tectono-morphologic evolution should thus be reappraised.