Glacial landforms on the Siberian termination of the Lomonosov Ridge – hints for a 1 km thick pan-Arctic ice shelf?

• Main Authors: Schlager, Ursula, Jokat, Wilfried, Weigelt, Estella, Gebhardt, Catalina
• Format: Conference Object
• Language: unknown
• Published: 2021
• Subjects: Arctic; Arctic Ocean; Ice Shelf; Lomonosov Ridge; Sea ice
• Online Access: https://epic.awi.de/id/eprint/55960/; https://epic.awi.de/id/eprint/55960/1/Presentation15minPDF_AGU2021_epic.pdf; https://epic.awi.de/id/eprint/55960/2/Presentation05minPDF_AGU2021_epic.pdf; https://hdl.handle.net/10013/epic.405212bb-9277-49cf-bced-4e1787468a5f

The Arctic Ocean is mainly surrounded by continents and large shelf seas. During glacial times the ocean was covered by thick sea ice and/or fragments of ice sheets and ice shelfs. Evidences for this are erosion of the seafloor along the surrounding margins and also in the center of the Arctic Ocean. Glacial processes have modified the present and past seafloor down to water depths of more than a kilometer. This observation triggered a discussion about the existence of a 1 km thick pan-Arctic ice shelf during the LGM or earlier. The Lomonosov Ridge is a continental sliver and submarine ridge in the Arctic Ocean which rises several kilometers above the adjacent deep sea plains. It has no onshore catchment areas like the glaciated margins surrounding the Central Arctic Ocean which are strongly modified by glaciers and ice streams. Nevertheless, evidences for glacial erosion are found on the ridge. In our contribution, we investigate the Siberian termination of the Lomonosov Ridge between 81˚-84˚N with bathymetric, sediment echosounder and multichannel seismic reflection data acquired with RV Polarstern in 2014 and 2018. Bathymetry data reveal three sets of glacial lineations, differentiated by their orientation, which are traced to a maximum water depth of ~1250 m. A flat-topped ridge crest shows recessional moraines and pockmarks that might be glacially induced. Sediment echosounder and multichannel seismic reflection data show deeper units with well stratified reflections that are truncated and incised. Based on these data, we will discuss the pros and cons for the existence of a past 1 km thick pan-Arctic ice shelf on the Siberian termination of Lomonosov ridge.