SUBGLACIAL CONTROL ON ICE FLOW IN NORTHERN GREENLAND

Recent studies, focusing on the dynamic behavior of the Greenland Ice Sheet, revealed rapid changes that cannot be explained by existing ice-sheet models. Better understanding of these processes is needed for improving numerical ice-sheet models and constraining future ice sheet evolution. An important control on fast glacier flow is the basal temperature regime and the presence of lubricating meltwater or water-saturated sediments. Observations suggest localized melting in northern Greenland that can only be explained if large spatial variations in geothermal heat flux are invoked. Such variations may be associated with pronounced subglacial topography, or they may result from lateral variations in crustal thickness and lithology.

We combine geophysical (airborne magnetics and gravity, ice-penetrating radar) and remote sensing (laser altimetry, visible, NIR and SAR imagery) data to map subglacial geology and to establish the relationship between geologic boundaries, subglacial geomorphology and ice surface features in NW Greenland. We also investigate the origin and evolution of prominent bedrock channels and subglacial hills and their effect on ice flow. Our results suggest that over the Precambrian Franklinian Basin, ice flow is primarily controlled by bed conditions and not by bed topography. Subglacial melting appears to show a pattern related to the magnetic anomalies of the central Greenland magmatic province and prominent bedrock troughs and surface features follow the boundaries of major basement structures.