Influence of Biotite and Foliation on Brittle Deformation of Gneiss
Contribution to Book
Atlas of Mylonitic and Fault-Related Rocks
Princeton University Press
Experimental work of Borg and Handin (1966) and Gottschalk and others (1990) indicates that relatively small quantities of biotite and gneissic foliation may influence the orientation, location, and density of fractures and subsequent faults in brittlely deformed rocks. The examples presented here are from naturally deformed granite gneisses in southwestern Montana, and are analogous to the features described in previous experimental work. Archean gneisses in the foot-wall and hanging wall of the Scarface thrust were deformed at depths no greater than 4 km during early Tertiary, east-directed thrusting (Schmidt and others, 1993). The protolith consists of well-foliated, medium-grained quartz-feldspar-biotite gneiss. Few fractures exist in undeformed samples of the rock.
Evans, J. P. , 1998, Influence of biotite and foliation on brittle deformation of gneiss, in: Atlas of mylonitic and fault-related rocks, A. W. Snoke, J. A. Tullis, and V. R. Todd, eds., Princeton University Press, p. 40-41.