DETECTING THE IMPRINT OF FAST ICE FLOW ON MODERN PROGLACIAL FIELDS: AN EXAMPLE FROM MÝRDALSJÖKULL ICE CAP, SOUTHERN ICELAND

Investigation of modern glacial systems is critical, to both enhance understanding of the current and changing dynamics of modern glaciers and to aid in the interpretation of paleoice sheet dynamics in previously glaciated regions. Understanding the location, duration and size of ice streams, areas of fast ice flow within ice sheets, is key to interpreting ice behaviours and dynamics. However, it is difficult to identify their former presence in paleoglacial deposits as little is known about the sediments and landforms they generate. Consequently, modern surge-type glaciers, which also undergo periodic rapid ice flow, have been proposed as analogues for paleoice streams that developed in the Laurentide and Scandinavian Ice Sheets that covered much of the northern hemisphere during the Quaternary. This study focuses on the impact of fast ice flow on the generation of sediments and landforms at two outlet glaciers of the Mýrdalsjökull Ice Cap in southern Iceland, western Slettjökull and Öldufellsjökull. A combination of landsystem and sedimentological analysis was used to study the process-form relationship of landforms and sediments exposed in the proglacial fields of these two glaciers. Preliminary mapping of the two proglacial fields was completed using a 5 m digital elevation model (DEM) and aerial imagery. An unmanned aerial vehicle was used to collect aerial imagery of areas impacted by historical surges. These data were input into Agisoft Metashape and used to create high resolution (2 cm) DEMs of the areas of interest. Sedimentological data were collected from exposures along river banks to identify sediment types associated with different landforms. The field and remotely sensed data were then compared with similar data from surging and non-surging proglacial fields to analyse the impact of fast ice flow on the landform-sediment assemblages. The Slettjökull and Öldufellsjökull glacial fields have few of the characteristics commonly reported from other surge-type glacier forefields in Iceland, despite having experienced multiple recorded surge events. This study highlights the need for further investigation of these dynamic systems to refine the understanding of the impact of fast ice flow on proglacial fields in both modern and previously glaciated regions.