Petrography and provenance of volcaniclastic sands recovered from the Izu-Bonin Arc, Leg 126

Abstract

These sands are dominantly composed of volcanic-lithic and plagioclase-feldspar grains derived from the Izu-Bonin magmatic arc and intrarift volcanoes. The glass color of volcanic fragments ranges from black (tachylite) to brown to colorless; individual samples usually contain a mixture of glass colors. There is an increase in the proportions of pumice colorless glass, felsitic grains, and quartz within sediments of the incipient backarc basin (Sumisu Rift), as compared with the forearc-basin sites. -from Author