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Abstract. Measurement of absolute and relative amounts of dust and salt deposited in the polar ice record is central to several fields of study, including nutrient delivery, atmospheric deposition of trace elements, past wind strengths, dust provenance, and other aspects of climate and geochemical history. We present a method intended to give a more accurate picture than has been possible before of the total amounts and relative proportions of the dust and salt deposited by the atmosphere into polar ice. It also permits us to distinguish different compositional types of dust in the ice. The method is based on precise measurement of a suite of several metals whose proportions contrast strongly between dust and salt and vary substantially between dust types. We apply the method to a small suite of ice samples from the Taylor Dome core in coastal West Antarctica. In full glacial times, when total impurities were high and dust dominated over salt, wind strength in the West Antarctic region was apparently high, and extensive sea-ice cover prevented incorporation of salt into the atmospheric load. At the termination of the glacial period, increased salt in the dust-salt mixture indicates that sea ice diminished, but wind strength continued high, and unchanged dust composition indicates unchanged source areas. At about 10,000-11,000 y.B.P., sea-ice cover appears to have briefly returned to glacial conditions, but wind conditions remained in the milder postglacial condition. Soon after, sea ice retreated, and an abrupt change in dust composition indicates changed source materials or terranes. If extended by analysis of more samples from more sites, such information on salt and dust could provide firm constraints on past wind strengths, extent of sea-ice cover, deposition fluxes of salt and dust, and changing continental source areas of dust, for both polar regions of the Earth. The method we present here for measuring the absolute and relative amounts of dust and salt and for distinguishing different types of dust in ice relies on the accurate determination by a sensitive analytical technique (stable isotope dilution (SID) followed by thermal ionization mass spectrometry (TIMS)) of a suite of six major, minor, and trace alkali and alkaline earth metals (K, Rb, Cs, Ca, Sr, Ba). The geochemical abundances and behaviors of these metals are well known, and their proportions contrast between rock dust and sea salt. The metals vary between rock types to allow us to assign general sources of the dust. 18,487

A buried, old volcanic body (pre-Komitake Volcano) was discovered during drilling into the northeastern flank of Mount Fuji. The pre-Komitake Volcano is characterized by hornblende-bearing andesite and dacite, in contrast to the porphyritic basaltic rocks of Komitake Volcano and to the olivine-bearing basaltic rocks of Fuji Volcano. K-Ar age determinations and geological analysis of drilling cores suggest that the pre-Komitake Volcano began with effusion of basaltic lava flows around 260 ka and ended with explosive eruptions of basaltic andesite and dacite magma around 160 ka. After deposition of a thin soil layer on the pre-Komitake volcanic rocks, successive effusions of lava flows occurred at Komitake Volcano until 100 ka. Explosive eruptions of Fuji Volcano followed shortly after the activity of Komitake. The long-term eruption rate of about 3 km 3 /ka or more for Fuji Volcano is much higher than that estimated for pre-Komitake and Komitake. The chemical variation within Fuji Volcano, represented by an increase in incompatible elements at nearly constant SiO 2 , differs from that within pre-Komitake and other volcanoes in the northern Izu-Bonin arc, where incompatible elements increase with increasing SiO 2 . These changes in the volcanism in Mount Fuji may have occurred due to a change in regional tectonics around 150 ka, although this remains unproven.