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The creation of sheeted dykes is a perpetual and continuous process that promotes the phenomenon known as seafloor spreading. Seafloor spreading is the creation of new oceanic crust by volcanic activity at mid-ocean ridges, and as magma continues to rise and solidify at mid-ocean ridges, the existing
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formations such as pillow lava, a common extrusive rock created near areas of volcanic activity on the seafloor. Although some magma is able to reach the surface of oceanic crust, a considerable amount of magma solidifies within the crust. Dykes are formed when the rising magma that does not reach
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Mid-ocean ridges with a spreading rate greater than or equal to 90 mm/year are considered to be fast-spreading ridges. Due to the large amounts magma being expelled from the asthenosphere in a relatively short period of time, these formations typically protrude much higher from the seafloor.
101:, consistent with most dykes having been split by later dykes. It is also common for the chilled margins to be consistently on one side, suggesting that most dykes in any one exposure were gradually moved away from the spreading centre by further stages of intrusion in a constant location.
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The layer of sheeted dykes that makes up the lower part of Layer 2 of the oceanic crust is typically between one and two kilometres thick. At the top, the dykes become increasingly separated by screens of lava, while at the base they become separated by screens of gabbro.
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Mid-ocean ridges with a spreading rate less than or equal to 40 mm/year are considered to be slow-spreading ridges. These formations are typically characterized by a large depression in the seafloor, known as
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Hole 504b, Costa Rica - Hole 504b is a scientific ocean drilling program that burrowed 1562.3 m below the seafloor directly through layers of sediment exposing sheeted dykes and pillow lava.
132:. These subaqueous mountain ranges are made up of newly created oceanic crust due to tectonic plates moving away from each other. In response to the separation of plates, magma from the
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Cartoon to explain how one-sided chilled margins develop in sheeted dyke complexes from repeated intrusion at one location - four stages of intrusion are shown, with 1 being the earliest
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continues to cool, as the existing seafloor moves away from the area of divergence, and additional magma is intruded and cools. In some tectonic settings slices of the oceanic crust are
255:
Phillips-Lander, Charity M.; Dilek, Yildirim (March 2009). "Structural architecture of the sheeted dike complex and extensional tectonics of the
Jurassic Mirdita ophiolite, Albania".
153:-like sequences of rocky columns within the seafloor. Ophiolites are formed when these sections of oceanic crust are revealed above sea level and embedded within continental crust.
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divergence travels through a fracture in the earlier formed oceanic crust, feeding the lavas above and cooling below the seafloor forming upright columns of igneous rock.
290:
Karson, Jeffrey A. (2019). "From
Ophiolites to Oceanic Crust: Sheeted Dike Complexes and Seafloor Spreading". In Srivastava, R.; Ernst, R.; Peng, P. (eds.).
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Karson, Jeffrey A.; Hurst, Stephen D.; Lonsdale, Peter (1992). "Tectonic rotations of dikes in fast-spread oceanic crust exposed near Hess Deep".
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Rothery, D. A. (March 1983). "The base of a sheeted dyke complex, Oman ophiolite: implications for magma chambers at oceanic spreading axes".
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is subject to upwelling, pushing hot magma up towards the seafloor. The magma that reaches the surface is subject to fast cooling and creates
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The individual dykes typically range in thickness from a few centimetres to a few metres. Most of the dykes show evidence of one-sided
231:- A sheeted dyke complex on the coast of Oman has been discovered to have been formed during a single sea-floor spreading episode.
624:"Fluid evolution in oceanic crustal layer 2: fluid inclusion evidence from the sheeted dike complex, Hole 504B, Costa Rica Rift"
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307:
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186:, and variations in spreading rate determine the geometry of the mid-ocean ridge being created at plate boundaries.
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Dykes are perpetually formed as long as magma continues to flow through the plate boundary, creating a distinct,
505:"Geophysical constraints on the crustal architecture of the Troodos ophiolite: results from the IANGASS project"
451:
468:
Marinoni, Laura B (June 2001). "Crustal extension from exposed sheet intrusions: review and method proposal".
351:
Hutton, D.H.W.; Aftalion, M.; Halliday, A.N. (1985). "An
Ordovician ophiolite in County Tyrone, Ireland".
657:
662:
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Nicolas, A.; Boudier, F. (1991). "Rooting of the
Sheeted Dike Complex in the Oman Ophiolite".
503:
Mackenzie, G.D.; Maguire, P.K.H.; Coogan, L.A.; Khan, M.A.; Eaton, M.; Petrides, G. (2006).
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the surface cools into upright columns of igneous rock beneath areas of divergence.
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Robinson, Paul T.; Malpas, John; Dilek, Yildirim; Zhou, Mei-fu (2008).
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182:. The rate at which new oceanic crust is created is referred to as
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593:. Petrology and Structural Geology. Vol. 5. pp. 39–54.
630:. Proceedings of the Ocean Drilling Program. 137/140: 191–198.
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Proceedings of the Ocean
Drilling Program, Scientific Results
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older dykes are pushed out of the way to make room for newer
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10.1130/0091-7613(1992)020<0685:TRODIF>2.3.CO;2
294:. Springer Geology. Singapore: Springer. pp. 459–492.
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due to low spreading rate. (Middle and bottom) Creation of
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Ophiolite
Genesis and Evolution of the Oceanic Lithosphere
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391:"The significance of sheeted dike complexes in ophiolites"
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Kelley, Deborah S.; Vanko, David A.; Gu, Chifeng (1995).
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Series of parallel dykes characteristic of oceanic crust
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124:Sheeted dyke complexes are most commonly found at
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61:, dykes are formed when magma beneath areas of
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470:Journal of Volcanology and Geothermal Research
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292:Dyke Swarms of the World: A Modern Perspective
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330:. New York: Springer-Verlag. pp. 61–62.
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326:Schmincke, Hans-Ulrich (2004).
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128:marked by the presence of
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25:Sheeted dykes in exposed
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199:Slow-spreading ridges
190:Fast-spreading ridges
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47:sheeted dike complex
43:sheeted dyke complex
568:1983JGSoc.140..287R
521:2006GeoJI.167.1385M
482:2001JVGR..107...27M
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365:1985Natur.315..210H
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165:(Top) Creation of
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658:Igneous petrology
608:978-94-010-5484-3
359:(6016): 210–212.
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218:Troodos Ophiolite
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263:(1–4): 192–206.
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171:mid-ocean ridges
130:mid-ocean ridges
119:mid-ocean ridges
73:(emplaced) upon
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167:rift valley
652:Categories
438:(8): 685.
239:References
145:Ophiolites
37:, England)
540:2381/2236
401:(11): 4.
395:GSA Today
328:Volcanism
79:ophiolite
27:ophiolite
225:Syncline
220:, Cyprus
212:Examples
138:basaltic
85:Geometry
71:obducted
35:Cornwall
564:Bibcode
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361:Bibcode
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223:Maydan
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180:seabed
67:Magma
57:. At
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