HR: 08:50h
AN: V21C-04    [Abstracts]
TI: Tephrochronology of North Pacific Volcanic Arcs - data from ODP Leg 145
AU: * Prueher, L
EM: lprueher@usgs.gov
AF: USGS, MS 974 Denver Federal Center PO Box 25046, Lakewood, CO 80225 United States
AB: Volcanic ash layers in deep-sea sediment from the North Pacific provide a record of volcanism in North Pacific Island Arcs. 450 ash layers were counted in deep-sea cores from the Ocean Drilling Project Sites 882, 883, and 887, in order to determine frequency of eruption, ash thickness, episodes of regional volcanism, and the impact of multiple eruptions on the intensification of Northern Hemisphere Glaciation. Episodes of explosive volcanism occurred approximately at 0.2-0.5, 1.5-1.7, and 2.5-2.65 Ma in the Kamchatka-Kurile volcanic arc, and 0.15-.4, 1.5-1.7, and 2.55-2.65 Ma in the eastern Aleutian volcanic arc. Aeolian mineral grains and volcanic glass were removed from the deep-sea sediments using a method developed at the University of Michigan. A new method of heavy-liquid separation was developed to separate volcanic glass from terrestrial mineral grains. The glass was isolated in order to calculate the flux of volcanic glass in order to quantify the climatic impact of the eruptions. The amount of volcanic glass in the sediments between visible ash layers was measured and used as a proxy for sulfate aerosols in the atmosphere. Eruption ages were determined by magnetic reversal stratigraphy. Argon-argon geochronology will be used to compare the ages and to further test the usefulness of the argon-argon method for determining the age of volcanic glass.
DE: 8404 Ash deposits
DE: 8409 Atmospheric effects (0370)
DE: 9355 Pacific Ocean
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting