The effect of crystal shape and growth history on fabric and permeability of magma mush
Brenna A. Halverson 1, Katherine J. Dobson2, Madeleine Humphreys1, Fabian Wadsworth3, Alejandro Cuetos4
Affiliations: 1Department of Earth Sciences, Durham University, Durham, UK; 2Civil and Environmental Engineering, University of Strathclyde, Glasgow, UK; 3Earth & Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, Germany; 4Department of Physical, Chemical, and Natural Systems, Universidad Pablo Olavide, Seville, Spain
Presentation type: Talk
Presentation time: Thursday 15:00 - 15:15, Room S150
Programme No: 1.9.4
Abstract
Magmas in the crust are stored in crystal-rich mush zones with complex crystal inter- and over-growth textures and inter-crystal melt pathway geometries. For crystal-poor eruptions, large volumes of melt must migrate through the crystalline framework. To better understand the evolution of these melt pathways with time, we present an investigation of simulated magma mushes, comprised of three distinct cuboidal crystal morphologies with axial aspect ratios of 7:6:1, 20:6:1, and 15:5:3, respectively. Each of these morphologies undergoes associated changes in growth rate along different axes, with the faces perpendicular to the long axes growing at the fastest rates, and those perpendicular to the short axis growing most slowly. As growth of these crystals progresses, we calculate the permeability of melt through the system, constraining evolution of both crystalline intergrowth and melt-migration routes during mush formation. This research provides a detailed examination of the effects that different crystal shapes and associated growth patterns have upon magma crystallization and efficacy of melt permeability within magma bodies, with implications for timescales of eruption and recharge in volcanic systems.