A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz , plagioclase , and alkali feldspar . Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz-poor monzonites to quartz-rich quartzolites . As only two of the three defining mineral groups (quartz, plagioclase, and alkali feldspar) need to be present for the rock to be called a granitoid, foid -bearing rocks, which predominantly contain feldspars but no quartz, are also granitoids. The terms granite and granitic rock are often used interchangeably for granitoids; however, granite is just one particular type of granitoid.
5-729: The Chambers-Strathy Batholith , also called the Strathy-Chambers Batholith , is a large granitoid batholith complex in the Temagami region of Northeastern Ontario , Canada . Named for the Chambers and Strathy townships, its compositions range from pink to grey quartz monzonite to granodiorite and intrudes through rocks of the Temagami Greenstone Belt . 47°08′N 79°47′W / 47.14°N 79.78°W / 47.14; -79.78 This article about
10-400: A specific Canadian geological feature is a stub . You can help Misplaced Pages by expanding it . This Northern Ontario geographical article is a stub . You can help Misplaced Pages by expanding it . Granitoid Granitoids are diverse; no classification system for granitoids can give a complete and unique characterization of the origin, compositional evolution, and geodynamic environment for
15-416: The plutonic rocks outcrop. Granitoids can form in all tectonic environments. There are numerous exceptions to these generalizations. For example, granitoids can form in anorogenic environments , a granitoid source rock can be from the mantle (for example, at intraplate hotspots ) and the melting mechanism can be radiogenic crustal heat . This igneous rock -related article
20-490: The evolution to granitoid magmas requires a thermal disturbance to ascent though continental crust. Most granitoids are generated from crustal anatexis , the partial melting of the crust; however the mantle may contribute both heat and material. Granitoids can occur coeval with volcanic rocks that have equivalent chemical composition (granite– rhyolite , syenite– trachyte , granodiorite – dacite etc.) however, these extrusive rocks are often eroded so just
25-468: The genesis of a granitoid. Accordingly, multiple granitoid classification systems have been developed such as those based on: geochemistry , modal content, emplacement depth, and tectonic regime . There are several generalizations that apply to the majority of granitoids. Typically, granitoids occur where orogeny thickens continental crust either by subduction yielding a continental arc or by convergence yielding continental collisions. Generally,
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