Crustal structure beneath Eastern Greenland

The conjugate Atlantic passive margins of western Norway and eastern Greenland are characterized by the presence of coast-parallel mountain ranges with peak elevations of more than 3.5 km close to Scoresby Sund in Eastern Greenland. Knowledge about crustal thickness and composition below these mountain belts is needed for assessing the isostatic balance of the crust and to gain insight into possible links between crustal composition, rifting history and present-day topography of the North Atlantic Region. However, the acquisition of geophysical data onshore Greenland is logistically complicated by the presence of an up to 4 km thick ice sheet, permanently covering the largest part of the land mass. Hence previous seismic surveys have only been carried out offshore and near the coast of Greenland, where little information about the continental part of the crust could be gained. To get insight into crustal thickness and composition below the Greenland ice sheet, the TopoGreenland project collects the first ever seismic data onshore Greenland. Wide-angle data was acquired along an EW-trending profile, extending 350 km inland from the approximate edge of the stable ice cap near Scoresby Sund. Data is recorded by 350 Reftek Texan receivers for 10 equidistant shot points along the profile. We use forward ray tracing modelling to construct a two-dimensional velocity model from the observed travel times. These results show the first images of the subsurface velocity structure beneath the Greenland ice sheet and provide a link between the composition of the crust and the present-day topography of Greenland.