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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 . [ 1 ] Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites .
Tonalite–trondhjemite–granodiorite (TTG) rocks are intrusive rocks with typical granitic composition (quartz and feldspar) but containing only a small portion of potassium feldspar. Tonalite , trondhjemite , and granodiorite often occur together in geological records , indicating similar petrogenetic processes. [ 1 ]
Trondhjemite is an orthoclase-deficient variety of sodium-rich tonalite with minor biotite as the only mafic mineral, named after Norway's third largest city, Trondheim. [6] Tonalites, together with granodiorites, are characteristic of calc-alkaline batholiths formed above subduction zones. [7]
Type locality, also called type area, is the locality where a particular rock type, stratigraphic unit or mineral species is first identified. [1] If the stratigraphic unit in a locality is layered, it is called a stratotype, whereas the standard of reference for unlayered rocks is the type locality. [2] The concept is similar to type site in ...
Diorite is an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and sometimes pyroxene.The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite.
The location map of the Dharwar Craton. The shaded area represents the Dharwar Craton. Generated from GeoMapApp (Ryan et al., 2009). [1]The Dharwar Craton is an Archean continental crust craton formed between 3.6-2.5 billion years ago (), which is located in southern India and considered the oldest part of the Indian peninsula.
Troctolite / ˈ t r ɒ k t ə l aɪ t / (from Greek τρώκτης 'trout' and λίθος 'stone') is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene.
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