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erupt on the ocean floor and produce the extrusive rock pumice. Pumice is a light-weight glass with a vesicular texture that differs from scoria in its silicic composition and therefore floats.
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are volcanic depressions formed after an erupted volcano collapses. Resurgent calderas can refill with an eruption of rhyolitic magma to form the extrusive rock rhyolite like the
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194:. Crystals in aphantic rocks are small in size due to their rapid formation during eruption. Any larger crystals visible to the human eye, called
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are formed by high viscosity lava that piles up, forming a dome shape. Domes typically solidify to form the rich in silica extrusive rock
206:. The extrusive rocks scoria and pumice have a vesicular, bubble-like, texture due to the presence of vapor bubbles trapped in the magma.
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often have andesitic magma and typically form the extrusive rock andesite. Andesitic magma is composed of many gases and melted
198:, form earlier while slowly cooling in the magma reservoir. When igneous rocks contain two distinct grain sizes, the texture is
48:) weight contents. Blue area is roughly where alkaline rocks plot; yellow area where subalkaline rocks plot. Original source: *
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The texture of extrusive rocks is characterized by fine-grained crystals indistinguishable to the human eye, described as
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which are released as free gas, then it may cool with large or small vesicles (bubble-shaped cavities) such as in
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are large, slow forming volcanoes that erupt fluid basaltic magma that cools to form the extrusive rock
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The main effect of extrusion is that the magma can cool much more quickly in the open air or under
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or scoria cones violently expel lava with high gas content, and due to the vapor bubbles in this
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Practical
Volcanology: Lecture Notes for Understanding Volcanic Rocks from Field Based Studies
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refers to rocks formed by magma which cools below the surface.
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Fissure volcanoes pour out low viscosity basaltic magma from
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A volcanic rock from Italy with a relatively large six-sided
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domes form the extrusive rock dacite, like in the case of
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A classification of igneous rocks and glossary of terms
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76:(diameter about 1 mm) surrounded by a fine-grained
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390:. Upper Saddle River, New Jersey: Prentice-Hall.
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148:at all, instead becoming a natural glass like
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257:lava, the extrusive basalt scoria is formed.
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453:: CS1 maint: multiple names: authors list (
415:. New York City, New York: Springer-Verlag.
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109:flows out (extrudes) onto the surface as
580:Principle of cross-cutting relationships
473:Petrology : Principles and Practice
202:, and the finer crystals are called the
174:. Other examples of extrusive rocks are
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439:Németh, Károly, Martin, Ulrike (2007).
140:. Sometimes, a residual portion of the
16:Mode of igneous volcanic rock formation
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590:Principle of inclusions and components
507:Igneous and volcanic textures - images
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236:to form the extrusive rock basalt.
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443:. Geological Institute of Hungary.
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361:Fundamentals of Physical Geology
575:Principle of lateral continuity
411:Schmincke, Hans-Ulrich (2004).
210:Extrusive bodies and rock types
155:If the magma contains abundant
113:or explodes violently into the
585:Principle of faunal succession
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363:. New Delhi, India: Springer.
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1:
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64:, Blackwell Science, Oxford.
792:. You can help Knowledge by
386:Winter, John DuNann (2001).
36:to their relative alkali (Na
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325:"Extrusive rock - geology"
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550:principles and processes
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101:formation in which hot
86:petrographic microscope
740:Mass wasting processes
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359:Jain, Sreepat (2014).
94:refers to the mode of
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616:Petrologic principles
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702:Marine transgression
570:Law of superposition
475:. Berlin: Springer.
471:Sen, Gautam (2014).
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283:Yellowstone Caldera
157:volatile components
759:Geology portal
717:Sediment transport
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44:O) and silica (SiO
26:classification of
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125:. In contrast,
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794:expanding it
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328:. Retrieved
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119:pyroclastics
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82:thin section
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639:Exfoliation
200:porphyritic
196:phenocrysts
146:crystallize
833:Categories
697:Subsidence
659:Compaction
654:Diagenesis
644:Weathering
422:3540436502
397:0132403420
330:21 October
312:References
261:Lava domes
204:groundmass
115:atmosphere
78:groundmass
74:phenocryst
629:Extrusive
624:Intrusive
491:864593152
449:cite book
413:Volcanism
227:pyroxenes
223:feldspars
169:vesicular
144:fails to
31:extrusive
28:aphanitic
634:Volcanic
548:Geologic
306:Seamount
295:See also
279:Calderas
265:obsidian
192:aphantic
180:andesite
176:rhyolite
150:obsidian
138:crystals
134:seawater
84:under a
247:rocks.
186:Texture
96:igneous
489:
479:
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367:
269:dacite
251:Cinder
245:mantle
219:basalt
172:basalt
165:scoria
161:pumice
142:matrix
788:is a
255:mafic
167:, or
152:.
107:Earth
103:magma
40:O + K
790:stub
487:OCLC
477:ISBN
455:link
417:ISBN
392:ISBN
365:ISBN
332:2018
225:and
178:and
123:tuff
111:lava
58:1989
24:IUGS
121:or
56:);
54:ed.
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
