A JOURNEY TO THE CENTER OF THE ASTHENOSPHERE: A NUMERICAL EXPLORATION OF MAGMA PRODUCTION BENEATH MID OCEAN RIDGE AND SUBDUCTION ZONE SYSTEMS

Author

Francesca C. Burkett, Southern Illinois University CarbondaleFollow

Date of Award

5-1-2024

Degree Name

Master of Science

Department

Geology

First Advisor

Conder, James

Abstract

2-D numerical computer models based on thermodynamic and kinematic principles have become invaluable tools for simulating geodynamic processes at these systems. Numerical models have proven effective for allowing the examination and computation of multiple factors simultaneously, providing scientists with an important resource with which to study complex systems. Previously, for instance, numerical models have been used for examining different factors involved in magma production at subduction zones and mid ocean ridges by modelling the influence and interplay of factors such as the effect of hydration and the influence of the depth of the fault between the two plates on the melting (van Keken, 2003; van Keken 2008). Additional models have explored the thermal structure of subduction zones and its relationship to the processes involved at convergent boundaries, including magma production (van Keken, 2023a). Syracuse et al. (2010) used numerical models for subduction zones, creating thermal models that examined dehydration and melting in subduction zones with a variety of slab geometries, convergence velocities, ages and structures. Still others have shown that thermal structure affects melt production, formation of arc volcanoes, dehydration, and seismicity, modelling the effects of varying slab dip, plate convergence velocity, plate age, etc. (Syracuse et al., 2010; Hayes et al, 2018). However, none have yet utilized models to systematically investigate magma production at either subduction zones or mid-ocean ridges to specifically examine both batch and fractional melting with the combination of multiple controlling factors including slab dip, convergence rate, hydration, minerology, and slab age. This project investigated the processes surrounding magma production at subduction and mid-ocean ridge systems through the creation of a numerical model and utilization of the developed model to explore the effects of a multitude of parameters on fractional and batch melting, as well as investigated the incorporation of incompatible elements, and other processes of interest in subduction and mid ocean ridge systems.