trondhjemite
Sign in to saveTrondhjemites are leucotonalites, a variety of leucocratic tonalite in which the modal mineralogy mostly consists of plagioclase in the form of albite to andesine, >20% quartz, and <10% alkali feldspar. Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites.
Key facts
- Rock.image
- File:HKU 香港大學 Stephen Hui Geological Museum 許士芬地質博物館 the oldest rocks from China TTG Migmatite Taishan complex n old trondhjemitic gneiss Baijiafen Anshan Oct 2016 Lnv.jpg
- Rock.caption
- Tonalite-trondhjemite-granodiorite migmatite (left) and trondhjemitic gneiss (right) from northern China
- Rock.name
- Trondhjemite
- Rock.type
- Igneous
- Rock.composition
- plagioclase: (albite to andesine), quartz, alkali feldspar
via Wikipedia infobox
~2 min read
Encyclopedic overview
4 sectionsContents
- Formation
- Notes
- References
- Further reading
Trondhjemites are leucotonalites, a variety of leucocratic tonalite in which the modal mineralogy mostly consists of plagioclase in the form of albite to andesine, >20% quartz, and <10% alkali feldspar. Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites.
Trondhjemites are common in Archean terranes, occurring in conjunction with tonalite and granodiorite as the TTG (tonalite-trondhjemite-granodiorite) orthogneiss suite. Trondhjemite dikes also commonly form part of the sheeted dike complex of an ophiolite.
Excerpted from Wikipedia’s “trondhjemite” article, available under the CC BY-SA 4.0 licence.