Dehydration Reaction Kinetics and the Global Water Cycle

Plate boundary processes involve the production, consumption, and transport of fluids, as well as the evolving physical properties of the solid earth. Metamorphic reactions are at the roots of these processes. Model predictions of subduction zone phenomena (including devolatilization, magma genesis, and eclogitization) and regional orogeny require some quantification of the rate and timescale over which metamorphic reactions in the crust and mantle proceed.

Garnet frequently grows during dehydration, thus preserving a record of these reactions during metamorphism. In this research, we are integrating high precision zoned garnet geochronology with thermodynamic analysis of garnet forming dehydration reactions to directly measure dehydration fluxes in subduction zones and regional orogeny. Ongoing research has focused on well preserved garnet-bearing blueschists on the islands of Sifnos and Syros, Greece as well as large rotated garnets from Townshend Dam, Vermont.

Relevant Grant Support

NSF Grant EAR-1250497 "Collaborative Research: Field-Based Quantification of Dehyration Flux from Subducting Lithologies, Syros and Sifnos, Greece", 1/1/13, PI: Baxter; Co-PIs: Caddick

NSF Grant EAR-0911582 “Collaborative Research: Developing a Practical and Quantitative Method for Measurement of Metamorphic Porphyroblast Crystallization Kinetics and Strain Rate”, 7/1/09, PI: Hirsch; Co-PIs: Stowell, Baxter

NSF Grant EAR-0547999 “CAREER: Rates and Timescales of Metamorphic Reactions at Convergent Plate Boundaries”, 1/1/06, PI: Baxter

Selected Publications

Baxter EF, Caddick MJ, 2013. Garnet as a proxy for progressive subduction zone dehydration. Geology, v.41, p. 643-646 (PDF)

Dragovic B, Samanta LM, Baxter EF, Selverstone J, 2012. Using Garnet to Constrain the Duration and Rate of Water-Releasing Metamorphic Reactions During Subduction: An Example from Sifnos, Greece. Chemical Geology, v. 314-317. p. 9-22. (link to paper)