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.
| 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
- 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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