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map of plutonic rock of North AmericaPluton is a general term for any large igneous intrusion of crystallized magma. Rocks that emplaced in large intrusive structures are termed "plutonic", whereas those that form in small intrusions are called "hypabyssal".

Plutonic igneous rocks cooled and crystallized from intrusive or irruptive magma within the Earth's crust. Plutonic rocks exhibit a fine-grained aphanitic texture if the magma cooled close to the surface in volcanic necks or feeder pipes, with grain size increasing through to coarse-grained, phaneritic textures for magmas that cooled very slowly at great depth in very large magma chambers. (image - click to enlarge - plutonic rock of North America)

Plutonic rock types include granite, diorite, gabbro, and rhyolite. Plutonic structures include huge solidified magma chambers called batholiths, laccoliths, stocks, bysmaliths, and lopoliths, while smaller hypabyssal structures include diapirs, dikes and dikelets, ring dykes, sills, volcanic necks and plugs, and cone sheets. Less commonly encountered plutonic structures include: phacoliths, cactoliths, ductoliths, harpoliths, sphenoliths, akmoliths, and ethmoliths. Chonoliths are intrusive igneous structure with shapes so irregular that they do not fall into the normal categories. Any intrusive structure may later become exposed at the surface by erosion.

(Veins are finite volumes within rocks, which are filled with crystals of minerals precipitated from hot (aqueous) fluids.)

intrusive emplacement / structures: ▪ batholithboudinbysmalithconcordantconformablediapirdiatremedikediscordantenclaveshypabassallaccolithslopolithsplutonsillsstratavolcanovein

structures reflecting flow/crystallization within magma chambers: ▪ cumulatesenclavesschlierenxenoliths

magmatic processes: ▪ assimiliationexchange of volatilesfractional crystallizationigneous rocksigneous structuresmagmamagmatic differentiationmagmatic mixingophiolite complexestectonics extrusive: ◘ lavavolcanoesvulcanism

igneous rocks: ◘ basaltcumulatesdunitesenclavesfelsic (sial) ◘ gabbrogranitegranodioritegroundmasskeratophyreslavamafic (sima) ◘ magmaophiolite complexespegmatitesperidotiteperidotiteporphyryschlierentonalitesxenocrystxenoliths

Maps of North American rock types : rock types - metamorphic, plutonic, sedimentary, volcanic; tapestry of time and terrain, terrain.

[images : dike, sill, diapir, laccolith, batholith]

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