Aeromagnetic reconnaissance over the Riiser-Larsen Ice Shelf, east Antarctica

A single 160 km long aeromagnetic profile across the Riiser-Larsen Ice Shelf from the coast to Vestfjella, indicates shallowing of the depth to the magnetic source from about 2 km below the sea floor at the ice front to a depth equivalent to ice thickness at the position of the grounding line about 80 km farther south. Adjoining marine multichannel seismic data and sonobuoy measurements suggest that the material below the ice shelf may be a prograding wedge of sediments of seismic velocity less than 3.5km/s. Parallel northeast trending magnetic anomalies between the Plogen and Dagvola nunataks in Vestfjella can best be modelled as three large dyke swarms at depth