Chemical composition of volcanic glasses in visible tephra layers found in a 2503 m deep ice core from Dome Fuji, Antarctica

Twenty-six ash layers were found in a 2503 m deep ice core from Dome Fuji station, East Antarctica. In order to gain information about the sources of ash particles found in the layers, major and trace element abundances have been measured. The particles found in 21 of the 26 layers were commonly a few tens of pm in size, suggesting that they originated from volcanoes located in and around the Antarctic. On the basis of comparison of the major-element compositions of these tephras with reference to volcanic rocks and ash, the tephras were divided into three types: (1) tholeiitic basalt to dacite, (2) calc-alkaline andesite, and (3) trachyandesite to trachyte. The source regions appear to be (1) South Sandwich Islands, Southern Ocean, (2) South Shetland islands, Antarctica, and/or a southern part of the volcanic zone of the Andes, and (3) Marie Byrd Land and/or Victoria Land, Antarctica, respectively. The tephras found in the other five ash layers were significantly smaller (< 5 mu m), suggesting that they traveled over longer distances. Abundances of trace elements for the alkaline tephra collected from one layer revealed a possible genetic link to volcanic rocks from Marie Byrd Land. In order to correlate between ice cores from Dome Fuji and Vostok, Antarctica, which are widely separated, we found coeval ash layers serving as stratigraphic markers of Antarctic ice cores. A comparison of profiles of O-18/O-16 (delta O-18) and H-2/H-1 (delta D) for the Dome Fuji and Vostok cores indicates that eight ash layers are equivalent in the two cores. A clear correlation was found for the chemical compositions of six of these ash layers, indicating a high potential for key correlation beds between the deep ice cores from Dome Fuji and Vostok.