Rehydration of the lower crust, fluid sources and geophysical expression

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This project aims to explore a long-standing mystery: the origin of deep crustal electrical conductors detected by magnetotelluric imaging of tectonically stable crust. These features occur in cratons of all ages, and commonly cross cut structures and lithologies. This project aims to investigate the hypothesis that such features are the record of ancient deep crustal fluid flow, which modified the rock electrical properties. Using an exceptionally exposed natural laboratory preserving large-scale rehydration of anhydrous lower crust, the project plans to determine the source of fluids and the compositional changes they induced. It then plans to experimentally determine changes in resistivity induced by fluid flow and use that data to model the magnetotelluric response at crustal scale.