Mantle signals in arcs: Transport models from geochemistry and seismicity

Lead PI: Philipp Ruprecht

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

February 2015 - January 2018
Project Type: Research

DESCRIPTION: The proposed study will explore magma transport rates in the middle to lower crust of convergent margin volcanoes and therefore address one of the most fundamental questions in geodynamics: How do magmas move from their source region in the mantle wedge to the surface? Furthermore, results from this study will provide first-order controls on arc magma petrogenesis, connecting the mantle source and melting process with the crustal plumbing system as well as provide insights on the aggregation of mantle-derived melts beneath arc volcanoes. The project is designed to use an integrative approach combining constraints from geochemistry, seismology, and fluid dynamics. The project will lead to a better understanding of magma transport beneath active volcanoes and improve our interpretation of monitoring dataset from such volcanoes. Current models for magma transport in convergent margins suggest the prolonged storage and evolution of mantle-derived melts in the crust. This project will test whether a fast mode of magma transport even for large, long-lived arc magma systems exists and what conditions may facilitate such rapid ascent from the mantle to the surface. The time-integrative nature of geochemical data often precludes a direct comparison to geophysical signals that record transient processes. However, geochemical speedometers employing fast elemental diffusion in zoned magmatic crystals may bridge this observational gap and advance the application of geochemical tools to short time scale magmatic processes otherwise only investigated through geophysics. Such techniques have been successfully employed for near-surface magmatic processes; this projects aims at extending such approaches to the entire crustal magma ascent path.