Reaction enhanced permeability during retrogressive metamorphism

摘要: Abstract Retrogressive metamorphism is in most cases associated with influx of external fluids into igneous or metamorphic rocks low to negligible initial permeabilities. Thus fluid migration some process that creates the necessary channels for migration. One such mechanism volume changes resulting from volatilization reactions. Petrographic studies a partly serpentinized troctolite Duluth complex Minnesota reveal how increase solid hydration olivine phenocrystals generates an extensive network microfractures surrounding plagioclase-dominated matrix. This microfracture allows hydrous penetrate further rock. A 2-D spring-network model illustrates expanding polygons (or non-spherical grains) elastically deforming matrix cause dilatant microfracturing and porosity generation even if overall stresses are compressive. The emphasises infiltration may be promoted by stress heterogeneities set up