Development of FluidVeins during Deformation of Fluid-rich Rocks close to the Brittle^Ductile Transition: Comparison between Experimental and Physical Models

To understand the factors affecting the orientation and spacing of fluid veins in deforming silicate matrices, experimental results on the deformation of sub-micron flint have been examined. New results and data from the literature show that deformation of flint at high-temperature, fluid-rich conditions (6 vol. % fluid) and strains, , less than 0·1^0·2 leads to the development of fluid band-ing orthogonal to ~3, consistent with theoretical expectations. On the other hand, above these strains and with fluid-poor conditions (1 vol. %), conjugate R1and R2 Riedel bands are observed, related to brittle fracture.These latter bands cross the first generation of 458 bands formed at lower . It is of note that for strains up to 0·5 the strain rate _ remains uniform throughout the entire sample, but that above this value deformation is concentrated in a single prominent Riedel band. To understand and rationalize these observations, one-dimensional numerical modelling of fluid^rock separatio