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

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.本研究针对南大洋大西洋海域表层沉积物中的磁化率（magnetic susceptibility）与砾石组分的空间分布展开调查，旨在重建磁性矿物与冰筏碎屑（ice-rafted debris）的物源区及近期输运路径。研究观测到，磁化率峰值出现在富铁镁质源岩分布海域的近岸区域，例如毛德皇后地（Queen Maud Land）与南极半岛北部。大陆边缘区域的冰川成因碎屑输入，以及随后由底流与浊流对细粒物质的再沉积作用，造成了砾石含量与磁化率数值的区域差异。但在深海区域，来自远端物源区的冰筏碎屑与浊积岩的混合作用，使得磁化率信号呈现均一化分布。在莫德海山（Maud Rise）与阿斯特里德海岭（Astrid Ridge）这类海底高地，粉尘输入可能是磁性矿物的额外物源。