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.
4-498: The Panguipulli Batholith is a granitic batholith of Jurassic age located in the Andes around Panguipulli Lake in southern Chile . This Los Ríos Region location article is a stub . You can help Misplaced Pages by expanding it . This article about a regional geological feature is a stub . You can help Misplaced Pages by expanding it . Granitic Granitoids are diverse; no classification system for granitoids can give
8-575: A continental arc or by convergence yielding continental collisions. Generally, 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
12-493: A complete and unique characterization of the origin, compositional evolution, and geodynamic environment for 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
16-416: 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
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