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to rupture the skin and start the formation of a new eruption point nearer the vent. This process produces a series of interconnecting lobate shapes that are pillow-like in cross-section. The skin cools much faster than the inside of the pillow, so it is very fine-grained, with a glassy texture. The magma inside the pillow cools slowly, so it is slightly coarser-grained than the skin, but it is still classified as
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reaches the surface but, as there is a large difference in temperature between the lava and the water, the surface of the emergent tongue cools very quickly, forming a skin. The tongue continues to lengthen and inflate with more lava, forming a lobe, until the pressure of the magma becomes sufficient
575:"Furnes, H. & Skjerlie, F.J. 1972. The significance of primary structures in the Ordovician pillow lava sequence of Western Norway in an understanding of major fold pattern. Geological Magazine, 109, 315-322"
414:
Kuroda, N.; Shiraki, K.; Urano, H. (1988-10-01). "Kuroda, N., Shiraki, K. & Urano, H. 1988. Ferropigeonite quartz dacites from Chichi-jima, Bonin
Islands: Latest differentiates from boninite-forming magma".
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indicator in geology; that is, study of their shape reveals the attitude, or position, in which they were originally formed. Pillow lava shows it is still in its original orientation when:
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are characterized by thick sequences of discontinuous pillow-shaped masses, commonly up to one meter in diameter. They form the upper part of
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The pillows might have a tapered base downwards, as they may have molded themselves to any underlying pillows during their formation.
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are found towards the top of a pillow (because the gas trapped as part of the rock is less dense than its solid surroundings).
542:"Scientists Study 'Glaciovolcanoes,' Mountains of Fire and Ice, in Iceland, British Columbia, US ScienceDaily, Apr. 23, 2010"
514:
343:"McCarthy, T. & Rubidge, B. 2008. The story of earth and life, Chapter 3, The first continent. 60-91, Struik Publishers"
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Walker, George P L. (1992-08-01). "Walker, G.P.L. 1992. Morphometric study of pillow-size spectrum among pillow lavas".
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that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or
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Geology and geodynamics of
Iceland, R.G. Trønnes, Nordic volcanological Institute, University of Iceland
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2005. Volcanoes and the environment by Joan Martí, Gerald Ernst, Cambridge
University Press, 488 pp.
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The presence of pillow lavas in the oldest preserved volcanic sequences on the planet, the
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129:. As new oceanic crust is formed, thick sequences of pillow lavas are erupted at the
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Lava containing characteristic pillow-shaped structures due to subaqueous extrusion
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Eon. Pillow lavas are used generally to confirm subaqueous volcanism in
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They occur wherever lava is extruded underwater, such as along marine
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NeMO Explorer, NOAA - Contains link to video of pillows being formed
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The pillow structures show a convex (rounded) upper surface.
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Pillow lava at
Boatman's Harbour. Oamaru, New Zealand.
375:"Late Palaeozoic Ultramafic Lavas in Yunnan, SW China"
157:, thus exposing the oceanic segment above sea level).
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the composition (richer in silica - resulting in an
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102:), the larger the pillows, due to the increase in
182:Pillow lavas are also found associated with some
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501:Harmon, Russel S.; Rapela, Carlos W. (1991).
149:sequence (when a segment of oceanic crust is
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573:H. Furnes and F. J. Skjerlie (1972-07-01).
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503:Andean Magmatism and Its Tectonic Setting
417:Contributions to Mineralogy and Petrology
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66:composition, although pillows formed of
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23:Pillow lava on the ocean floor of Hawaii
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262:Weathered Archean pillow lava in the
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186:at an early stage of an eruption.
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348:. Web.wits.ac.za. Archived from
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94:are known. In general, the more
281:Pillow lava formations from an
141:. Pillow lavas and the related
44:Layer 2 of normal oceanic crust
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211:Pillow lavas can be used as a
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577:. Geolmag.geoscienceworld.org
507:Geological Society of America
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305:, Rizal Province, Philippines
123:constructive plate boundaries
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62:Pillow lavas are commonly of
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7:
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10:
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400:10.1093/petrology/44.1.141
373:Fang, N.; Niu, Y. (2003).
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207:Use as a way-up criterion
264:Temagami Greenstone Belt
100:Intermediate composition
460:Bulletin of Volcanology
145:form part of a classic
194:They are created when
143:sheeted dyke complexes
106:of the erupting lava.
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24:
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22:
379:Journal of Petrology
184:subglacial volcanoes
137:from the underlying
36:subaqueous extrusion
472:1992BVol...54..459W
429:1988CoMP..100..129K
391:2003JPet...44..141F
301:Pillow basalt from
285:sequence, Northern
614:Structural geology
544:. Sciencedaily.com
480:10.1007/BF00301392
437:10.1007/BF00373580
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38:. Pillow lavas in
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516:978-0-8137-2265-8
246:Pillow lava near
155:continental crust
80:basaltic andesite
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509:. p. 24.
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355:on 2009-04-07
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317:Pillow basalt
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40:volcanic rock
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579:. Retrieved
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357:. Retrieved
350:the original
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201:fine grained
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28:Pillow lavas
27:
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619:Volcanology
177:metamorphic
151:thrust over
50:Composition
608:Categories
581:2014-03-10
548:2014-03-10
359:2014-03-10
329:References
110:Occurrence
488:129797887
445:128613176
287:Apennines
283:ophiolite
190:Formation
166:Barberton
147:ophiolite
104:viscosity
68:komatiite
311:See also
220:Vesicles
92:rhyolite
90:or even
84:andesite
76:boninite
64:basaltic
468:Bibcode
425:Bibcode
387:Bibcode
322:Spilite
289:, Italy
266:of the
233:Gallery
179:belts.
173:Archean
133:fed by
119:volcano
116:hotspot
72:picrite
513:
486:
443:
248:Oamaru
213:way-up
96:felsic
88:dacite
484:S2CID
441:S2CID
353:(PDF)
346:(PDF)
303:Baras
196:magma
135:dykes
32:lavas
511:ISBN
164:and
162:Isua
153:the
30:are
476:doi
433:doi
421:100
395:doi
125:of
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
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