Identification and correlation of distal tephra layers in deep-sea sediment cores, Scotia Sea, Antarctica

Quaternary deposits in six sediment cores from the Scotia Sea, Antarctica, were examined for the presence of volcanic ash layers. The cores were recovered from water depths of 3369-4025 m. Altogether, 23 ash layers were found, 18 of which have been investigated by electron-probe microanalysis. Deception Island is identified as the source of all the ash layers analyzed. The upper ash layer in each core can be correlated across all six cores, over a distance of 400 km, on the basis of its unusual bimodal composition, major oxide geochemistry and strati graphic position. Two other ash layers can also be correlated between several of the cores.