Heat flux and crustal thickness in Greenland adjacent to and under the ice sheet

Within Greenland, the ice-free Scoresbysund region (Central East Greenland) hosts the hottest and largest number of geothermal springs, the shallowest seismic Moho depths, and the highest heat flux estimates from two magnetics-based approaches. Crustal magnetic thickness models made using both global satellite (MF-7, xChaos) and some local airborne data sets (EMM2010) point to thin magnetic crust in the Scoresbysund region; and thick magnetic crust in NW and southernmost Greenland. Recent seismic results suggest that the Scoresbysund region, the largest contiguous ice-free region within Greenland, hosts the shallowest Moho depths (24-27 km). Temperatures of up to 62 deg C have been measured from the geothermal springs here. Adjacent ice-covered regions are likely to be most heavily affected by the relatively high geothermal activity. Because hot springs and geothermal anomalies have only been identified along the coast where they are easily accessible, and because little is known of their areal extent, we are attempting more detailed mapping of these geothermal anomalies using the TIRS data set (100 m spot size) on the recently launched Landsat-8 satellite. Magnetic and seismic results suggest that heat fluxes in the Scoresbysund region may be as much as four times larger than that in NW and southernmost Greenland, on the assumption of steady-state 1-d heat conduction and heat production restricted to the crust. Existing magnetics-based crustal thickness and heat flux models under and adjacent to the Greenland ice sheet are based on satellite and low-altitude airborne data sets. Magnetic field measurements from high (20 km) altitude are strongly preferred because of their increased sensitivity to wavelengths characteristic of the entire magnetic crust, and their ability to suppress local remanent magnetic field signatures. As a consequence, we are developing a proposal for a high-altitude airborne magnetic and thermal IR mission to map the geothermal heat flux under and adjacent to the Greenland ice sheet. The results of the proposed mission, IceBase, will reduce the uncertainty in future sea level rise, in turn allowing a more informed assessment of its impact on society. The mission, part of NASA's Earth Venture program, would begin in 2014 if selected.