Reconstructing ice-margin retreat using delta morphostratigraphy

• Published in: Scientific Reports
• Main Authors: Dietrich, Pierre, Ghienne, Jean-François, Normandeau, Alexandre, Lajeunesse, Patrick
• Other Authors: Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Dynamique de la lithosphère et des bassins sédimentaires (IPGS) (IPGS-Dylbas), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Geological Survey of Canada Dartmouth (GSC Atlantic), Geological Survey of Canada - Office (GSC), Natural Resources Canada (NRCan)-Natural Resources Canada (NRCan), Centre d'Etudes Nordiques (CEN), Université Laval Québec (ULaval)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; Canada; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/hal-01716133; https://hal.archives-ouvertes.fr/hal-01716133/document; https://hal.archives-ouvertes.fr/hal-01716133/file/Dietrich%20et%20al.,%202017%20Reconstructing%20ice%20margin%20retreat.pdf; https://doi.org/10.1038/s41598-017-16763-x

International audience The paleogeographic reconstruction of the successive inland positions of a retreating ice sheet is generally constrained by mapping moraines. However, deltaic complexes constructed by sediment-charged meltwater can also provide a record of the retreating ice-margin positions. Here, we examine a serie of ice-contact, ice-distal glaciofluvial and paraglacial depositional systems that developed along the Québec North Shore (eastern Canada) in the context of falling relative sea level during the northward retreat of the Laurentide Ice Sheet (LIS). Ice-contact depositional systems formed when the LIS was stillstanding along the Québec North Shore. Subsequent inland retreat of the ice margin generated glacial meltwaters feeding sediment to glaciofluvial deltas, leading to their rapid progradation. The retreat of the ice margin from drainage basins was marked by the onset of paraglacial processes such as the shutdown of delta progradation, severe fluvial entrenchment, and deposition of shallow-marine strata. Four end-member scenarios describe the spatial and stratigraphic distribution of these three depositional systems (ice-contact deposits, ice-distal glaciofluvial deltas, and paraglacial suites). They reflect both the inherited drainage basin physiography and the retreat pattern of the ice margin. Applied to twenty deltaic complexes, these end-members allowed us to refine the model of LIS-margin retreat over southeastern Québec.