Trondhjemite

Trondhjemite is a leucocratic (light-colored) intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites.

Trondhjemite
Igneous rock
Composition
oligoclase, other plagioclase

Trondhjemite is common in Archean terranes occurring in conjunction with tonalite and granodiorite as the TTG (tonalite-trondhjemite-granodiorite) orthogneiss suite.[1] Trondhjemite dikes also commonly form part of the sheeted dike complex of an ophiolite.

The name of the rock type is derived from the city of Trondheim, Norway.

Footnotes
  1. Philpotts & Ague 2009, p. 398.

References
  • Best, Myron G. (2002) Igneous and Metamorphic Petrology, Blackwell Publishing, 2nd ed. ISBN 1-4051-0588-7
  • Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. pp. 139–143. ISBN 9780521880060.


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