hide
Free keywords:
-
Abstract:
Ice-penetrating radar measurements and ice core drilling have shown that large parts of the north-central Greenland
Ice Sheet are melting from below. Locally these observational data indicate that an anomalously high geothermal
flux is needed to explain the observed basal ice melting. In this study we reconstruct the distribution of geothermal
flux in Greenland and identify a large-scale geothermal anomaly beneath the thick ice cover. The anomaly
represents a continuous 400-km-wide band of elevated heat flux, crossing Greenland from west to east. Our
combined analysis of seismic, gravity and tectonic data links the origin of this anomaly to Greenland’s passage
over the Iceland mantle plume between roughly 80 and 35 million years ago. Most of the observed subglacial
melting as well as previously suggested hydrological networks operating under the ice sheet occur within the
anomalous zone. Also the position of the enigmatic 750-km-long northeastern Greenland ice stream is controlled
by the enhanced ice deformation and basal sliding induced by the elevated heat flux. This rapid ice flow initiates at
the very heart of the reconstructed anomaly, where our study and observations indicate some of the highest rates
of basal ice melting in interior Greenland. Our findings suggest that the present-day subglacial hydrology and
rapid ice flow of the north-central Greenland Ice Sheet have their origin in tectonic events that predate the onset of
Greenland glaciations by many tens of millions of years.
