Impact of glacial erosion on synthetic (U-Th)/He detrital thermochronological age distributions: a new approach integrating glacial landscape modelling and thermal history inversion.

• Main Authors: Bernard, Maxime, Egholm, David L., Gallagher, Kerry, Steer, Philippe
• Other Authors: Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES), Department of Earth Sciences Aarhus, Aarhus University Aarhus
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; Greenland; Scoresby; Scoresby Sund; Sund; East Greenland; Ice Sheet
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-02091089

International audience Landscapes in Greenland have been deeply impacted by glacial erosion since the major cooling event at theEocene-Oligocene boundary and the initiation of the Greenland ice sheet between 5 and 30 Ma. Glacial erosioncreated deep and wide fjords including the largest in the world, the Scoresby Sund fjord, with a width greater than40 km. As fjords are unequivocally associated to glacial erosion, they represent a unique archive to assess theco-evolution of ice dynamics and landscapes during the Cenozoic. More specifically, the thermal history of rocksassessed from low-temperature thermochronology offer valuable insights to infer the long-term erosion history ofGreenland landscapes and the spatial distribution of ice over time. In the last decade, detrital thermochronologyhas been used to deduce spatial patterns of erosion within a catchment by considering just age probabilitydistributions functions (PDF). Recently, we have developed a new inverse approach to infer thermal historiesdirectly from detrital age distributions, without the need for in situ or vertical profile bedrock data.As this approach has shown promising results, we built the concept into the 3D landscape evolution model iSOSIA.Within the model we track sediment-particles resulting from erosion through multiple glaciation events, leadingto the formation of a major fjord comparable to those observed in Greenland. Each particle has an associatedthermochronological age, reflecting both the age distribution on the pre-glacial landscape and any modifications inresponse to glacial erosion. This information allows us to predict age distributions in a detrital sample anywherein the catchment. From these distributions we are then able to infer thermal histories, and to model the patternof erosion using an inverse approach. We present results of this modelling approach in a case study simulatingfjord development in East Greenland. The results highlight the importance of the strategy of detrital sampling forconstraining erosion history of ...