Silicic melt evolution in the early Izu-Bonin arc recorded in detrital zircons

Indiana University, Bloomington IN

Investigators

Abstract

Understanding the movement of tectonic plates across Earth's surface and the eventual return of these plates to the interior of our planet is central to our knowledge of Earth and its natural hazards such as earthquakes, tsunamis, and volcanic eruptions. This research focuses on understanding the formation, growth and eventual demise of volcanoes that mark the process of subduction, where tectonic plates return to Earth's interior. Minerals recovered from deep beneath the western Pacific Ocean floor by the International Ocean Discovery Program will be examined to decipher the history of volcano growth above an evolving subduction zone. The goals of the research are to use the chemistry of these minerals, called zircons, to better understand the life cycle of volcanoes, especially the timing of explosive volcanic eruptions. This research involves strong integration of research and education by involving undergraduate university students both in the laboratory and in field-based research projects at similar ocean floor volcanic systems that are now exposed on land in the Sierra Nevada mountains in the western United States. The goal of this study is to better understand the generation of silicic melts in a new and evolving intra-oceanic volcanic arc by searching for petrologic links between silicic volcanism and tonalitic arc plutonism and using this to better understand the evolution of the related magmatic processes through time. The primary goal of the research is to test whether (or to what extent) detrital zircons in drill cores, recovered by the International Ocean Drilling Program Expedition 351 and other legacy ocean drilling cores from a relatively primitive oceanic arc setting, record the regional and/or secular variation in silicic melts that crystallized magmatic zircon. Geochronology and trace element geochemistry of the zircons will allow comparisons between the thermal and melt chemical evolution recorded by arc-derived detrital zircons and by igneous zircons recovered in dredge samples of contemporaneous arc tonalite. This study will also generate an internally-consistent database of geochemical parameters for arc-derived zircons from a compositional range of marine arcs that will be useful for comparative zircon provenance studies, as these studies evolve to more commonly include key geochemical provenance indicators.