Dynamic

Dynamic metamorphism: rocks from environments such as large-scale ductile shear zones, where intense deformation is the dominant feature.
  • 123-2386 IMG Banded mylonite with lighter quartz-rich and darker micaceous layers, formed from semipelitic Moine schists. Small pale grains are porphyroclasts of minerals more resistant to dynamic recrystallisation, such as feldspar. From the Moine thrust zone at Knockan Crag, Assynt, NW Scotland.
  • 123-2388 IMG Very fine-grained quartz-rich mylonite with very few porphyroclasts. From the Moine thrust zone at Knockan Crag, Assynt, NW Scotland.
  • a98-kc3 Folded mylonite with quartz-rich and mica-rich bands. From the Moine thrust zone at Knockan Crag, Assynt, NW Scotland.
  • IMG 4380 This rock type, known locally as the 'oyster-shell rock', is a phyllonite - a mica-rich rock like a phyllite but formed by retrogression and shearing of Lewisian gneiss. The wavy foliation is organised into a set of spaced shear bands inclined at a small angle to the main schistosity. From the Moine thrust zone at Durness, NW Scotland.
  • IMG 5239 Mylonitised metagabbro in the Lizard Complex, Cornwall. Note the heterogeneous distribution of strain. It has been argued that some of these mylonites may have formed in the ocean floor on transform faults, rather than during later emplacement of the ophiolite.
  • IMG 6347 Pebble of strongly sheared granitic augen gneiss in a polymict conglomerate. From a slab in a stone merchant's yard.