A history of glaciations: the perks of combining recent and ancient morphostratigraphic archives

• Main Author: Dietrich, Pierre
• Other Authors: Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), European Geosciences Union
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2022
• Subjects: [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy; Canada; Furnes; glacier*; Ice Sheet
• Online Access: https://insu.hal.science/insu-03693959

International audience It is undoubtedly the observation of modern European Alps glaciers along with their erosive, transportational and depositional actions shaping the landscapes that first led scientists to reveal the existence of a ‘past ice age’ during which glaciers not so long ago covered northern Europe and North America. Based on similar observations, evidence for much more ancient (Permian, ca. 300 Ma) glaciers were simultaneously discovered in Wales. Since then, others glacial episodes punctuating the Earth history were successively discovered (Eyles, 2008), the oldest of which being the ‘Barberton diamictites of South Africa, dated back to 3.5 Ga (deWit & Furnes, 2016).The modern glaciation may serve as the basis to decipher past ice ages and associated climate dynamics that remain obscure as growing evidences indicate that these ancient glacial epochs share similarities, but also discrepancies, with the Cenozoic one, in term of tempos (ice ages encompassing periods of contraction-dilatation of ice) or forcing parameters (e.g., Ghienne et al., 2014; Kochhann et al., 2021; Montanez, 2021). Past ice dynamics may therefore be unraveled by the integration in time and space of punctual glacial processes whose interpretation is made on the basis of their modern and recent equivalent. The glacio-isostatic adjustment, for example, is a process well-known for the ultimate glacial cycle, as marked by widespread evidences such as the raised beaches of Scandinavia and Canada. Given its time span of completion however (a few tens of thousands of years), this process is hardly decipherable for ancient epochs, for which temporal resolution is intrinsically too low, therefore hindering our ability to constrain ancient ice-sheet dynamics. A stratigraphic model built upon recent glacial strata has been successfully extrapolated to both the Ordovician and Carboniferous-Permian ice ages, providing clues about pattern of glacial retreat of postglacial relative sea level changes. Similarly, the geomorphic and ...