Field Report for the Collection of Mafic Tephra from the Aleutians Islands between Unimak and the Island of Four Mountains (Alaska, USA)

This field report includes maps, photos and descriptions that document the location of samples collected for NSF-GeoPrisms project EAR-1456814, to study the origin, storage, ascent and eruption of volatile-bearing magmas in the Aleutians island arc. Samples are from summit eruptions and mafic side cones from Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok, Vsevidof and Cleveland volcanoes. Special targets included tephra from historic eruptions and scoria lapilli from cinder cones, to provide well-quenched material for the study of volatiles in olivine-hosted melt inclusion. We also include description of tephra samples generously collected by Chris Walls during EarthScope Plate Boundary Observatory installations on Unimak island in 2008. Field and lab assistants are gratefully acknowledged: Alex Lloyd, Amanda Lough, Anna Barth, Lindsay Buff. Expert help came from Pavel Izbekov, Kirsten Nicolaysen, Jessica Larsen, Janet Schaefer, Christoph Kern, Cynthia Werner, Merry Cai, Gene Yogodzinski, Game McGinsey, Billy d’Andrea, Chris Waythomas, Cheryl Cameron, Erik Hauri and Chris Nye. None of this work would have been possible without collaboration with the Alaska Volcano Observatory, and the skillful helicopter piloting of Dan Leary and the captain and crew of the R/V Maritime Maid. In addition to the NSF Grant cited above, Rasmussen also acknowledges support of a Jack Kleinman Grant to collect samples at Scotch Cap, Unimak.