Tephrochronology of the Kamchatka-Kurile and Aleutian arcs: evidence for volcanic episodicity

Volcanic ash layers in North Pacific deep-sea sediment provide a record of episodic explosive volcanism in the Kamchatka-Kurile and Aleutian arcs over the past five million years. We counted 450 ash layers, determined layer t hickness and cumulative ash thickness to quantify the flux of ash with time . We use this record to investigate the eruptive history of these arcs, tes t the reliability of the marine ash record, and inquire into the regional e pisodicity of North Pacific explosive volcanic history. Episodes of explosi ve volcanism occurred at approximately 0.2-0.5, 0.7-0.9, 1.5-1.7, and 2.5-2 .65 hla in the Kamchatka are and 0.15-0.4, 1.7-1.8, 2.55-2.65, and at 3.0-3 .1 hla in the eastern Aleutian are. These generally coeval eruptive episode s suggest that the pulses in explosive volcanism in the North pacific enume rated here and recognized by others are regionally episodic over a wide por tion of the Pacific rim and not just a response to local volcanogenic proce sses. (C) 2001 Elsevier Science B.V. All lights reserved.