Regional metamorphism in south-east Nelson

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Reed, J.J. 1958 Regional metamorphism in south-east Nelson. Wellington: Government Printer. New Zealand Geological Survey bulletin 60 64 p.

Abstract: Regional metamorphism in south-east Nelson has been mapped in an area of 500 square miles. Three metamorphic zones, based on the appearance of the index minerals chlorite, biotite, and garnet, are recognised in quartzo-feldspathic rocks (greywackes and argillites). The zones form a progressive metamorphic series in which the rank of metamorphism increases from east to west. It is concluded that metamorphism took place at a depth greater than 50,000 ft, essentially by oriented crystal-growth under a compressive stress normal to the schistosity planes (load metamorphism). The apparently conflicting metamorphic processes in south-east Nelson and Otago are reconciled if the schistosity planes in Otago originated by compression and thereafter functioned as planes of slip. (auth/EB)