CATACLASITE

Cataclasite (Grubenmann and Niggli, 1924) is the general name given to fine grained products of cataclasis which possess internal cohesion. The dominant mechanical processes involved are microfracturing and microbrecciation of crystals with intergranular sliding and rotation of grains. Because of the irregular behaviour of the fragmental components these crystals show no optically preferred orientation. Because of their general fine grain size and the moderate temperature and pressure conditions under which they form the individual components cohere together to form a rock. Banding is absent and the proportion of recognizable parent material to totally crushed rock has been used for further divide these into a) protocataclasite (> 50%), b) cataclasite (50-90%) and 3) ultracataclasite (> 90%). In the older literature, particularly that coming from British geologists, cataclasites were often termed flinty crush rock.