The geomorphological impacts of the deglaciation in the Skagafjörður area (northern Iceland)

• Main Author: Coquin, Julien
• Other Authors: Littoral, Environnement, Télédétection, Géomatique (LETG - Nantes), Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Rennes 2 (UR2), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Université de Brest (UBO)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Nantes, Denis MERCIER, Olivier BOURGEOIS
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2015
• Subjects: Deglaciation/Slopes/Paraglacial/Gravitational spreading/ Landslides; Déglaciation/Versants/Paraglaciaire/Etalements gravitaires/Glissements; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SHS.GEO]Humanities and Social Sciences/Geography; Skagafjörður; Iceland; Islande
• Online Access: https://tel.archives-ouvertes.fr/tel-01279835; https://tel.archives-ouvertes.fr/tel-01279835/document; https://tel.archives-ouvertes.fr/tel-01279835/file/THESE_VF.pdf

Located north of Iceland, the Skagafjörður area has experienced an ice shrinking during the Late Weichselian deglaciation.This period of transition from glacial to non-glacial conditions was characterized by significant impacts on reliefs and slope dynamics. The slope instabilities induced by the deglaciation operate in the form of: (i) slope deformations (i.e. gravitational spreading) and (ii) slope failures (i.e. mass-movements). This thesis is devoted to these slope readjustments which occurred in context of deglaciation. Accordingly, the thesis is related to the paraglacial geomorphology which focuses on “non glacial earth surface processes, sediment accumulations, landforms, landsystems and landscapes that are directly conditioned by glaciation and deglaciation” (Ballantyne, 2002). Two major uncertainties remains about: (i) the relationship between slopeinstabilities, both in the form of gravitational spreading and mass-movement, and the sequence of deglaciation, and (ii)the influence of paraglacial slope instabilities in the shaping of the erosional landforms usually attributed to the action ofglacial erosion processes (i.e. cirques and troughs). Main results carried out during this research highlight: (i) asignificant influence of paraglacial gravitational spreading and mass-movement respectively in the carving of troughsand cirques and (ii) a potential influence of gravitational spreading as a precursor of mass-movement, throughoutthe progressive degradation of slope stability induced by the gravitational deformation which may ultimately result inrock-slope failures. Située au nord de l’Islande, la région littorale du Skagafjörður a connu, au cours de la déglaciation du Weichsélien Tardif, une fonte massive des édifices glaciaires. Cette période de déglaciation a eu des impacts importants sur les reliefs et les dynamiques de versant. Les instabilités qui ont affecté les versants au cours de cette séquence s’expriment selon deux modalités principales : (i) les réajustements par déformation (i.e. les ...