Magnetic susceptibility and ice-rafted debris in surface sediments of the Atlantic sector of the Southern Ocean

Abstract.

Spatial distribution of magnetic susceptibility and the gravel fraction in surface sediments in the Atlantic sector of the Southern Ocean were investigated to reconstruct source areas and recent transport pathways of magnetominerals and ice-rafted debris. Maxima of magnetic susceptibility were observed offshore from areas where mafic source rocks occur, e.g. Queen Maud Land and the northern Antarctic Peninsula. The glacigenic input of debris and subsequent redeposition of fine material by bottom and turbidity currents on the continental margins result in regional variations of the gravel and susceptibility values. In the deep sea, however, the mixing of ice-rafted debris and turbidites from distal source areas causes a homogenous distribution of the susceptibility signal. On submarine elevations such as Maud Rise and Astrid Ridge, dust input may be an additional source for magnetominerals.