9417759 Cowan Brittle shear zones are common features in many tectonic settings, yet in spite of the importance of brittle shear zones and the probability that slip along some of them was seismogenic, there is as yet no unifying kinematic model relating the mesoscopic fabrics of the fault rocks within them to the strain paths or flow types characterizing shear zone deformation. This project will combine field data with extensive modeling to help develop and test the hypothesis that general coaxial shear is the predominant flow type as it is in ductile shear zones. Results are expected to improve the ability to interpret and kinematically analyze fabrics in brittle shear zones.