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Igneous Rocks - Coggle Diagram
Igneous Rocks
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magma crystallization
magmatic differentiation: process of modification of magma composition during crystallization. Can lead to formation of various igneous rock from single melt
crystal fractionation: in cooling magma, minerals crystallizing first settle down first,settling rate depends on timing of crystallization, density, size of crystals, viscosity. different minerals crystallize at different temp
result of crystal fractionation: residual melt becomes progressively more felsic (silica-rich). -> nature of volcanism depends on timing of extraction of residual magma
classification
based on rock texture
extrusive
form from relatively rapid cooling (due to great difference in temp.) of magma/ lava near earth's surface
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zB basalt (major component of oceanic crust, lots of it produced at mid-ocean ridges)
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lava ejected from volcano: pieces cool & solidify in air -> pyroclasts. come in various sizes: volcanic ash (<2mm), lapilli (intermediate), bombs (>6.4mm)
pyroclastic flow: explosive volcanic eruptions, sudden & massive release of mix of very hot gas & ash rushing down side of volcano at high speed. very dangerous
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sometimes combination of fine & coarse-grained, large & small crystals: porphyry. rock started to cool slowly beneath surface, then cooled faster as it approached surface
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