Timescales of magmatic processes from diffusional profiles recorded in minerals of the 2016-2017 eruption of Bogoslof Volcano, Alaska

Abstract

Every volcanic eruption is unique, and creates opportunities for scientists to gain insights on magma processes. Studying active volcanoes not only adds to our understanding of fundamental processes that shape our planet, but it is also importantly aids the scientic community to assess and mitigate the many hazards that volcanoes pose. The products of the 2016-2017 eruption of Bogoslof Volcano provide a unique opportunity for the application of diusion chronometry, due to the abundance of distinct, stepwise boundaries within three mineral phases: clinopyroxene, plagioclase, and amphibole. Given that diusion is driven by the presence of a chemical gradient, the compositionally stepwise boundaries between distinct zones can be used to investigate the diusion of elements within the crystals in order to constrain timing of the magmatic processes that created them, as well as crystal residence times. Here we present our analyses of these stepwise boundaries, and discuss the potential correlation of acquired diusional timescales from clinopyroxene with the other two mineral phases, in order to determine what magma processes lead to the formation of these boundaries, and when these processes occurred. Our results suggest that the stepwise boundaries in crystalline phases of the magmas erupted by Bogoslof in August 2017 formed due to mac recharge that resumed in March 2017 and occurred repeatedly until the cessation of the eruption in August 2017. Activity at Bogoslof during March 2017 is additionally characterized by increased seismicity and SO₂ rates, suggesting that our petrologic results are consistent with multiple interdisciplinary observations.