Crustal‐scale fluid transport: Magnitude and mechanisms

Fluids in the crust of the Earth play an important role in the geochemical and geophysical structure of the crust. They are responsible for a multitude of chemical/rock reactions and couple directly with geophysical processes and the geophysical imaging of the crust. The known depth of significant fluid reaction/transport has been increasing in recent years with the detailed study of drilled and exhumed solid phase samples. From both isotopic and chemical evidence, it is clear that meteoric fluids can penetrate at least 10 kilometers into the crust of the Earth (fluids have also been sampled directly from a depth of 12 km in the Kola Peninsula Drillhole) and the horizontal scale of fluid transport is now known to extend 100's of kilometers. Furthermore, as the kinetics and reaction dynamics (rather than simple equilibrium)are included to explain these observations, estimates of the fluid volumes (expressed as a water/rock ratio)required to emplace these fluid derived rock suites and deposits have increased steadily.