Collaborative Research: U-Series Constraints on Rhyolite Genesis at Medicine Lake Volcano

University Of Iowa, Iowa City IA

Investigators

Abstract

0001003/0000886 Reagan/Sims Because of its high viscosity and ability to concentrate water, rhyolite is capable of highly explosive eruptions that have the potential to cause widespread destruction. One of the most recent rhyolitic eruptions in the continental U.S. took place at the Medicine Lake volcano in northern California about 850 years ago. This eruption ejected about 1 km3 of rhyolite and dacite in lava flows and tephras from a chain of vents near the summit of the volcano. Much larger eruptions of rhyolite are possible from Cascades volcanoes (e.g. the climactic eruption of rhyolite from Crater Lake caldera 7700 years ago). Recent U-series data we collected on climactic ejecta from Crater Lake suggest that these rhyolites were generated over 105 year time-scales. The goal of our current project is to determine the time-scales of required to generate the smaller volumes of rhyolite erupted from the Medicine Lake volcano. We intend to determine whether these rhyolites migrate directly to the surface after being generated, or whether there is a potential that they are accumulating in the crust.