The record of fluid pressure variations by quartz geochemistry

Fluid pressure is a key parameter in the brittle, upper portion of the lithosphere, as it controls the stress necessary for faults to slip. In turn, fluid pressure is affected by brittle deformation, as large permeability changes occur during the seismic cycle. The interplay between fluid pressure and deformation is nevertheless mostly a theoretical model, as few data are available regarding the amplitude of fluid pressure at depth and its variations with time. Quartz veins constitute a potential time record of variations in precipitation conditions, as suggested by microstructures such as crack-seal or growth features. We examine in this work different sets of veins from convergent settings, spanning the seismogenic zone (T