The Posada–Asinara Line is a crustal-scale transpressive shear zone affecting the Variscan basement in northern Sardinia during Late Carboniferous time. We investigated a structural transect of the Posada–Asinara Line (Baronie) with the aid of geological mapping and structural analysis. N-verging F2 isoclinal folds with associated mylonitic foliation (S2) are the main deformation features developed during the Posada–Asinara Line activity (D2). The mineral assemblages and microstructures suggest that the Posada–Asinara Line was affected by a retrograde metamorphic path. This is also confirmed by quartz microstructures, where subgrain rotation recrystallization superimposes on grain boundary migration recrystallization. Crystallographic preferred orientation data, obtained using electron backscatter diffraction, allowed analysis of quartz slip systems and estimation of the deformation temperature, vorticity of flow and rheological parameters (flow stress and strain rate) during the Posada–Asinara Line activity. Quartz deformation temperatures of 400 ± 50 °C have been estimated along a transect perpendicular to the Posada–Asinara Line, in agreement with the syn-kinematic post-metamorphic peak mineral assemblages and the late microstructures of quartz. The D2 phase can be subdivided in two events: an early D2early phase, related to the metamorphic peak and low kinematic vorticity (pure shear dominated), and a late D2late phase characterized by a lower metamorphic grade and an increased kinematic vorticity (simple shear dominated). Palaeopiezometry and strain rate estimates associated with the D2late deformation event showed an intensity gradient increasing towards the core of the shear zone. The D2early deformation developed under peak temperature conditions, while the D2late event was active at shallower structural levels.

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Microstructure and texture data on the Main Central Thrust zone (MCTz) in central Himalaya, on two nearly N-S oriented valleys in the Manaslu range (Western Nepal), are provided. Kinematic indicators at the meso and microscale support a south-directed flow. From south to north, greenschist facies paragneiss in the garnet-zone pass to amphibolite facies rocks in the kyanite-zone, suggesting an up-section metamorphic temperature increase. Combining microstructures and data from two different texture analysers (X-ray Texture goniometry and crystal-fabric microanalyzer) allowed to link the temperature path (from 460°C to 600°C up-section) and kinematic vorticity estimates. The "orientation of oblique grain shape fabrics" method was applied, pointing out a general shear flow (40-56% of pure shear) at the MCTz top. Results are in line with a "decelerating strain-path" model, as relatively high simple shear components are recorded at deeper structural levels. This work highlights that the combination of X-ray texture goniometry and crystal-fabric microanalyzer techniques is a good strategy to ensure quartz full-fabric.