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▪ ice quake ▪ igneous structures

igneous structures

Magma is molten (igneous) rock formed when Earth's radioactivity heats rocks – because of Earth's geothermal gradient, the deeper in the Earth, the greater the temperature.

◙◙ Rock Index: Igneous Rocks ◙◙

Intrusion:
Magma that is emplaced below the surface when molten rock intrudes into or across strata of country rock cools and crystallizes in a variety of intrusive structures, including large plutonic and small hypabassal structures:

intrusive emplacement / structures: ▪ aplite, aplite dike (◙ aplite) ▪ batholith ▪ boudin ▪ bysmalith ▪ concordant ▪ conformable ▪ diapir ▪ diatreme ▪ dike ▪ discordant ▪ enclaves ▪ hypabassal ▪ laccoliths ▪ lopoliths ▪ pluton ▪ sills ▪ strata ▪ volcano ▪ vein ▪

structures reflecting flow/crystallization within magma chambers: ▪ cumulates ▪ enclaves ▪ schlieren ▪ xenoliths ▪

magmatic processes: ▪ anatexis ▪ assimiliation ▪ exchange of volatiles ▪ fractional crystallization ◘ igneous rocks ◘ igneous structures ◘ magma ▪ magmatic differentiation ▪ magmatic mixing ◘ ophiolite complexes ◘ tectonics

Extrusion:
When melted rock flows extrusively or erupts explosively at the surface is called lava – Hawaii's and Iceland's basalt lavas fountain or flow freely, while other lavas are sticky and explosive, producing deadly pyroclastic flows (Mount St. Helens, Vesuvius, Pinatubo).

extrusive: ▪ aphanitic texture ◘ lava ◙ tectonism ◘ volcanoes ▪ vulcanism

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