Spatial variation of pure and simple shear across transpressive shear zones: flow kinematics map of the Posada-Asinara shear zone (NE Sardinia, Italy)

Abstract

Flow kinematics estimations are necessary to determine how the deformation is partitioned in shear zones at different scales. Combining different scales of structural analysis with quantitative vorticity constraint allows a more rigorous examination of the kinematics of deformation. The Posada-Asinara shear zone (PASZ) in northern Sardinia (Italy) is a crustal-scale km-thick transpressive shear zone, separating the High-from the Medium-Grade Metamorphic Complex. After microstructural analysis, the vorticity of the flow was estimated to investigate the southernmost boundary of the PASZ, highlighting a dominant pure shear component far from the core of the shear zone. These results have been integrated with existing data to derive a regional-scale flow kinematic map of the Baronie region, highlighting the potentiality of automated geostatistical mapping to become a powerful complementary tool in the investigation of flow kinematics in collisional environments.