2019 Graduate Student Showcase
 

Title of Submission

Backarc Thermal Structure Controls Slab-Mantle Viscous Coupling Depth in Subduction Zones

Degree Program

Geosciences, PhD

Major Advisor Name

Matthew Kohn

Type of Submission

Scholarly Poster

Judging Session

Both Judging Sessions

Abstract

A primary feature of subduction zones is the point at which the slab and mantle viscously couple—defining the initiation of mantle wedge circulation. Here we consider the effects of the backarc thermal structure on coupling depth using two-dimensional thermomechanical models. Models show a strong correlation between coupling depth and backarc lithospheric thickness and coupling is always associated with the breakdown of antigorite. Backarc lithospheric thickness is a good predictor of coupling depth and can be indirectly estimated from surface heat flow. Consistently high backarc heat flow in circum-Pacific subduction zones may indicate a common depth of slab-mantle coupling globally.

Funding Information

NSF-PIRE/OIA Grant: PIRE: Exterra Field Institute and Research Endeavor (E-FIRE) to Matthew J. Kohn

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