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

Alessandro Petroccia^1
1Department of Earth Sciences, University of Turin, Via Valperga Caluso 35, 10125, Torino, Italy.
Corresponding author e-mail: alessandrogiovannimichele.petroccia@unito.it

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.

Variscan belt, transpression, vorticity, mylonite, strain partitioning.