Distorted Olivine Crystals: An unexploited record of magma storage at Kīlauea Volcano, Hawaiʻi
Penny E. Wieser, Marie Edmonds, John Maclennan and John Wheeler
Received Date: 28th March 19
Distorted olivines of enigmatic origin occur in basaltic lavas erupted in a wide range of volcanic settings (e.g. Hawaiʻi, Iceland, Reunion, Chile). At Kīlauea Volcano, they have been attributed to various processes: creep within rift zone dunites, grain collisions, or an early phase of dendritic growth. We assess these competing hypotheses using electron backscatter diffraction. Distorted olivines display crystallographic signatures distinct from those of dendritic growth, but consistent with deformation at high temperatures. The spatial distribution of eruptions containing distorted grains, along with the absence of adcumulate textures (e.g. internal melt films), is inconsistent with derivation from rift zone dunites. We suggest that distortions are generated by gravitational loading within melt-rich olivine cumulates with thicknesses of a few hundred metres accumulating within the summit reservoir. This mechanism invalidates petrological arguments for deep rift zone magma transport at Kīlauea, and accounts for the presence of deformed grains in many basaltic volcanoes.
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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.