Strain distribution and fabric development modeled in active and ancient transpressive zones

Abstract

A model based on kinematics of transpression allows the measurable internal parameters (simultaneous strain, fabric, and vertical elevation) to be simulated in relation to the macroscopically determined external parameters of transpressive zones (i.e., zone width, velocity, angle of convergence, and zone depth). We present a diagram of convergence angle against time for homogeneous transpression, where isolines of strain intensity D , strain symmetry K , and vertical elevation of rock samples are superposed. However, the distribution of internal strain parameters is sensitive to three types of strain partitioning: (1) Discrete partitioning results in general decrease of finite strain accumulations and in increase of pure shear component, (2) ductile partitioning splits the transpressional domain into a pure shear zone where strain accumulations decreases and in a wrench‐dominated zone where strain accumulations increases, and (3) viscosity partitioning is marked by different strain rates in zones of different viscosity and therefore by different strain parameters.