Geology Seminar: Olafur Ingolfsson: "Paleo-ice streams in North-eastern Iceland"
Olafur Ingolfsson from the University of Iceland will speak about :
"Paleo-ice streams in North-eastern Iceland"Ólafur Ingólfsson, Ívar Örn Benediktsson & Nína AradóttirUniversity of Iceland, Faculty of Earth Sciences Ice streams exercised critical control on the dynamics of the Weichselian Icelandic Ice Sheet. Our project aims to advance our understanding of the configuration, geomorphologic imprint, dynamics and recessional history of palaeo-ice streams in NE-Iceland. Our approach is to study glacial landform associations and sedimentary records, using multiple glacial geological, geomorphological, remote sensing, geophysical and chronological methods. The project is designed to elucidate the relative timing and spatial distribution of fast ice flow, the absolute timing of ice-stream/ice-sheet recession and thinning, and the mechanisms contributing to fast flow and the genesis of streamlined subglacial bedforms. We have identified areas where ice streams have run partially uncontrolled by local topography. These include onset zones with reticulated ridges and ribbed moraines and trunk-flow zones with highly-attenuated streamlined bedforms, characterized by swarms of large drumlins. The flow patterns are highly convergent and distinct. The geomorphic record also shows time-transgressive shifts in ice stream directions, where their location got more topographic focusing, perhaps signifying change from glacial maximum situation to large-scale, rapid deglaciation. Sedimentological and stratigraphical studies have highlighted extensively deformed sediments associated with the ice stream paths, as well as evidence of basal sliding and heavy scouring of bedrock. The paleo-ice streams have terminated in the ocean, probably reaching towards the shelf edge. Presently, high-resolution bathymetrical-/geophysical-/sediment data are lacking from the shelf areas. The project can provide insight into marine-ice sheet instability and the vulnerability of marine-terminating ice streams to sea-level rise, and further our understanding of ice sheet deglaciation dynamics. An important benefit of this project will be the value of its results for constraining numerical models aimed at illuminating subglacial landform development and the evolution of the Iceland ice sheet during the last deglaciation.