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{{Short description|Layer of rock that forms the continents and continental shelves}}
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{{Use dmy dates|date=October 2019}}
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[[File:Continental and oceanic crust.png|thumb|Continental and [[oceanic crust]] on the [[upper mantle]]]]
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'''Continental crust''' is the layer of [[igneous rock|igneous]], [[metamorphic rock|metamorphic]], and [[sedimentary rock|sedimentary]] rocks that forms the [[Continent#Geological continents|geological continents]] and the areas of shallow seabed close to their shores, known as ''[[continental shelf|continental shelves]]''. This layer is sometimes called ''[[sial]]'' because its bulk composition is richer in [[aluminium]] silicates (Al-Si) and has a lower density compared to the [[oceanic crust]],<ref>{{Cite book|editor-last=Fairbridge|editor-first=Rhodes W.|year=1967|title=The Encyclopedia of Atmospheric Sciences and Astrogeology|location=New York|publisher=Reinhold Publishing|page=323|oclc=430153}}</ref><ref>{{cite book|last1=Davis|first1=George H.|last2=Reynolds|first2=Stephen J.|last3=Kluth|first3=Charles F.|chapter=Nature of Structural Geology|title=Structural Geology of Rocks and Regions|edition=3rd|date=2012|publisher=[[John Wiley & Sons]]|page=18|isbn=978-0-471-15231-6}}</ref> called ''[[Sima (geology)|sima]]'' which is richer in [[magnesium]] silicate (Mg-Si) minerals. Changes in [[seismic wave]] velocities have shown that at a certain depth (the [[Conrad discontinuity]]), there is a reasonably sharp contrast between the more [[felsic]] upper continental crust and the lower continental crust, which is more [[mafic]] in character.<ref>{{cite book|first=Thomas|last=McGuire|chapter=Earthquakes and Earth’s Interior|title=Earth Science: The Physical Setting|date=2005|publisher=AMSCO School Publications Inc.|pages=182–184|isbn=978-0-87720-196-0}}</ref>
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Most continental crust is dry land above sea level. However, 94% of the [[Zealandia]] continental crust region is submerged beneath the [[Pacific Ocean]],<ref name=mortimer>{{cite journal|last1=Mortimer|first1=Nick|last2=Campbell|first2=Hamish J.|title=Zealandia: Earth's Hidden Continent|journal=[[GSA Today]]|volume=27|pages=27–35|year=2017|url=https://www.geosociety.org/gsatoday/archive/27/3/article/GSATG321A.1.htm|doi=10.1130/GSATG321A.1|url-status=live|archive-url=https://web.archive.org/web/20170217064642/https://www.geosociety.org/gsatoday/archive/27/3/article/GSATG321A.1.htm|archive-date=17 February 2017}}</ref> with [[New Zealand]] constituting 93% of the above-water portion.
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==Thickness and density {{anchor|Thickness|Density}}==
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[[Image:World relief map with isopachs of crustal thickness.jpg|thumb|350px|The thickness of [[Crust (geology)#Earth's crust|Earth's crust]] (km)]]
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The continental crust consists of various layers, with a bulk composition that is [[Intermediate composition|intermediate]] (SiO<sub>2</sub> wt% = 60.6).<ref>{{Cite book|date=1 January 2014|chapter=Composition of the Continental Crust|pages=1–51|doi=10.1016/B978-0-08-095975-7.00301-6|title=Treatise on Geochemistry|last1=Rudnick|first1=R.L.|last2=Gao|first2=S.|isbn=9780080983004}}</ref> The average density of the continental crust is about, {{cvt|2.83|g/cm3}},<ref>{{Cite journal|last1=Christensen|first1=Nikolas I.|last2=Mooney|first2=Walter D.|date=1995|title=Seismic velocity structure and composition of the continental crust: A global view|journal=[[Journal of Geophysical Research: Solid Earth]]|volume=100|issue=B6|pages=9761–9788|doi=10.1029/95JB00259|issn=2156-2202|bibcode=1995JGR...100.9761C}}</ref> less [[density|dense]] than the ultramafic material that makes up the [[Mantle (geology)|mantle]], which has a density of around {{cvt|3.3|g/cm3}}. Continental crust is also less dense than oceanic crust, whose density is about {{cvt|2.9|g/cm3}}. At {{cvt|25|to|70|km}} in thickness, continental crust is considerably thicker than oceanic crust, which has an average thickness of around {{cvt|7|to|10|km}}. Approximately 41% of Earth's surface area<ref>{{cite book|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780444538024001597|doi=10.1016/B978-0-444-53802-4.00159-7|chapter=Mechanism of Continental Crustal Growth|title=Treatise on Geophysics|year=2015|last1=Stein|first1=M.|last2=Ben-Avraham|first2=Z.|pages=173–199|isbn=9780444538031}}</ref>{{sfn|Cogley|1984}} and about 70% of the volume of [[Earth's crust]] are continental crust.{{sfn|Hawkesworth|Dhuime|Pietranik|Cawood|2010}}
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== Importance ==
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Because the surface of continental crust mainly lies above sea level, its existence allowed land life to [[evolution|evolve]] from marine life. Its existence also provides broad expanses of shallow water known as [[inland sea (geology)|epeiric seas]] and [[continental shelf|continental shelves]] where complex [[metazoan life]] could become established during early [[Paleozoic]] time, in what is now called the [[Cambrian explosion]].<ref>{{cite web|title=The Cambrian Period|url=http://www.ucmp.berkeley.edu/cambrian/cambrian.php|publisher=[[University of California Museum of Paleontology]]|access-date=30 November 2013|first1=Ben|last1=Waggoner|first2=Allen|last2=Collins}}</ref>
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==Origin==
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All continental crust is ultimately derived from mantle-derived melts (mainly [[basalt]]) through [[fractional crystallization (geology)|fractional differentiation]] of basaltic melt and the assimilation (remelting) of pre-existing continental crust. The relative contributions of these two processes in creating continental crust are debated, but fractional differentiation is thought to play the dominant role.<ref>{{Cite journal|last1=Klein|first1=Benjamin|last2=Jagoutz|first2=Oliver|date=1 January 2018|title=On the importance of crystallization-differentiation for the generation of SiO2-rich melts and the compositional build-up of arc (and continental) crust|journal=[[American Journal of Science]]|volume=318|issue=1|pages=29–63|doi=10.2475/01.2018.03|issn=1945-452X|bibcode=2018AmJS..318...29J|s2cid=134674805}}</ref> These processes occur primarily at [[volcanic arc|magmatic arcs]] associated with [[subduction]].
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There is little evidence of continental crust prior to 3.5 [[billion years|Ga]].<ref name="Hart">{{cite book|last=Hart|first=P. J.|title=Earth's Crust and Upper Mantle|publisher=[[American Geophysical Union]]|date=1969|pages=13–15|isbn=978-0-87590-013-1}}</ref> About 20% of the continental crust's current volume was formed by 3.0 Ga.<ref name="McCann2008">{{cite book|title=The Geology of Central Europe: Volume 1: Precambrian and Palaeozoic|publisher=[[Geological Society of London|The Geological Society]]|last=McCann|first=T.|year=2008|location=London|page=22|isbn=978-1-86239-245-8}}</ref> There was relatively rapid development on [[shield (geology)|shield]] areas consisting of continental crust between 3.0 and 2.5 Ga.<ref name=Hart/> During this time interval, about 60% of the continental crust's current volume was formed.<ref name="McCann2008"/> The remaining 20% has formed during the last 2.5 Ga.
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Proponents of a steady-state hypothesis argue that the total volume of continental crust has remained more or less the same after early rapid [[planetary differentiation]] of Earth and that presently found age distribution is just the result of the processes leading to the formation of [[craton]]s (the parts of the crust clustered in cratons being less likely to be reworked by plate tectonics).{{sfn|Armstrong|1991}} However, this is not generally accepted.{{sfn|Taylor|McLennan|2009}}
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== Forces at work ==
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In contrast to the persistence of continental crust, the size, shape, and number of continents are constantly changing through geologic time. Different tracts rift apart, collide and recoalesce as part of a grand [[supercontinent cycle]].{{sfn|Condie|2002}}
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There are currently about {{convert|7|e9km3|e9mi3|abbr=off}} of continental crust, but this quantity varies because of the nature of the forces involved. The relative permanence of continental crust contrasts with the short life of oceanic crust. Because continental crust is less dense than oceanic crust, when active margins of the two meet in [[subduction]] zones, the oceanic crust is typically subducted back into the mantle. Continental crust is rarely subducted (this may occur where continental crustal blocks collide and overthicken, causing deep melting under mountain belts such as the [[Himalayas]] or the [[Alps]]). For this reason the oldest rocks on Earth are within the cratons or cores of the continents, rather than in repeatedly [[crustal recycling|recycled oceanic crust]]; the oldest intact crustal fragment is the [[Acasta Gneiss]] at 4.01 [[Year#SI prefix multipliers|Ga]], whereas the oldest large-scale oceanic crust (located on the [[Pacific plate]] offshore of the [[Kamchatka Peninsula]]) is from the [[Jurassic]] (≈180 [[Year#SI prefix multipliers|Ma]]), although there might be small older remnants in the [[Mediterranean Sea]] at about 340 Ma.<ref>{{Cite web|url=https://www.newscientist.com/article/2100988-worlds-oldest-ocean-crust-dates-back-to-ancient-supercontinent/|title=World's oldest ocean crust dates back to ancient supercontinent}}</ref> Continental crust and the rock layers that lie on and within it are thus the best archive of Earth's history.{{sfn|Cogley|1984}}{{sfn|Bowring|Williams|1999}}
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The height of mountain ranges is usually related to the thickness of crust. This results from the [[isostasy]] associated with [[orogeny]] (mountain formation). The crust is thickened by the compressive forces related to subduction or continental collision. The buoyancy of the crust forces it upwards, the forces of the collisional stress balanced by gravity and erosion. This forms a keel or mountain root beneath the mountain range, which is where the thickest crust is found.{{sfn|Saal|Rudnick|Ravizza|Hart|1998}} The thinnest continental crust is found in [[rift]] zones, where the crust is thinned by [[detachment fault]]ing and eventually severed, replaced by oceanic crust. The edges of continental fragments formed this way (both sides of the [[Atlantic Ocean]], for example) are termed [[passive margin]]s.
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The high temperatures and pressures at depth, often combined with a long history of complex distortion, cause much of the lower continental crust to be metamorphic – the main exception to this being recent [[igneous intrusion]]s. Igneous rock may also be "underplated" to the underside of the crust, i.e. adding to the crust by forming a layer immediately beneath it.
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Continental crust is produced and (far less often) destroyed mostly by [[plate tectonics|plate tectonic]] processes, especially at [[convergent boundary|convergent plate boundaries]]. Additionally, continental crustal material is transferred to oceanic crust by sedimentation. New material can be added to the continents by the partial melting of oceanic crust at subduction zones, causing the lighter material to rise as magma, forming volcanoes. Also, material can be accreted horizontally when volcanic [[island arc]]s, [[seamount]]s or similar structures collide with the side of the continent as a result of plate tectonic movements. Continental crust is also lost through erosion and sediment subduction, tectonic erosion of forearcs, delamination, and deep subduction of continental crust in collision zones.{{sfn|Clift|Vannuchi|2004}} Many theories of crustal growth are controversial, including rates of crustal growth and recycling, whether the lower crust is recycled differently from the upper crust, and over how much of Earth history plate tectonics has operated and so could be the dominant mode of continental crust formation and destruction.{{sfn|Armstrong|1991}}
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It is a matter of debate whether the amount of continental crust has been increasing, decreasing, or remaining constant over geological time. One model indicates that at prior to 3.7 Ga ago continental crust constituted less than 10% of the present amount.{{sfn|von Huene|Scholl|1991}} By 3.0 Ga ago the amount was about 25%, and following a period of rapid crustal evolution it was about 60% of the current amount by 2.6 Ga ago.{{sfn|Taylor|McLennan|1995}} The growth of continental crust appears to have occurred in ''spurts'' of increased activity corresponding to five episodes of increased production through geologic time.{{sfn|Butler|2011|loc=See graphic}}

== See also ==
* [[Digital geologic mapping]]
* [[Geologic map]]
* [[Geologic province]]
* [[Lithosphere]]
* [[Mohorovičić discontinuity]]
* [[Oceanic crust]]
* [[OneGeology]]
* [[Plate tectonics]]
* [[Terrane]]

== References ==
{{reflist}}

=== Bibliography ===
{{Refbegin}}
* {{cite journal|last=Armstrong|first=R.L.|title=The Persistent Myth of Crustal Growth|journal=[[Australian Journal of Earth Sciences]]|year=1991|volume=38|issue=5|pages=613–630|doi=10.1080/08120099108727995|url=http://www.mantleplumes.org/WebDocuments/Armstrong1991.pdf|bibcode=1991AuJES..38..613A|citeseerx=10.1.1.527.9577}}
* {{cite journal|last1=Bowring|first1=S. A.|last2=Williams|first2=I. S.|title=Priscoan (4.00–4.03 Ga) orthogneisses from northwestern Canada|journal=[[Contributions to Mineralogy and Petrology]]|volume=134|year=1999|issue=134|pages=3–16|doi=10.1007/s004100050465|bibcode=1999CoMP..134....3B|s2cid=128376754}}
* {{cite web|last=Butler|first=Rob|title=Making new continents|year=2011|url=http://earth.leeds.ac.uk/assyntgeology/extra_info/ehistory.htm|access-date=29 January 2006|url-status=dead|archive-url=https://web.archive.org/web/20060301071038/http://earth.leeds.ac.uk/assyntgeology/extra_info/ehistory.htm|archive-date=1 March 2006}}
* {{cite journal|last=Cogley|first=J. Graham|title=Continental Margins and the Extent and Number of Continents|journal=[[Reviews of Geophysics]]|year=1984|volume=22|issue=2|pages=101–122|doi=10.1029/RG022i002p00101|bibcode=1984RvGSP..22..101C}}
* {{cite journal|last=Condie|first=Kent C.|title=The supercontinent cycle: are there two patterns of cyclicity?|journal=[[Journal of African Earth Sciences]]|year=2002|volume=35|issue=2|pages=179–183|doi=10.1016/S0899-5362(02)00005-2|bibcode=2002JAfES..35..179C}}
* {{cite journal|last1=Clift|first1=P.|last2=Vannuchi|first2=P.|title=Controls on Tectonic Accretion versus Erosion in Subduction Zones: Implications for the Origin and Recycling of the Continental Crust|journal=[[Reviews of Geophysics]]|year=2004|volume=42|issue=RG2001|pages=RG2001|doi=10.1029/2003RG000127|bibcode=2004RvGeo..42.2001C|hdl=1912/3466|s2cid=19916396|hdl-access=free}}
* {{cite journal|last1=Hawkesworth|first1=C.J.|last2=Dhuime|first2=B.|last3=Pietranik|first3=A.B.|last4=Cawood|first4=P.A.|last5=Kemp|first5=A.I.S.|last6=Storey|first6=C.D.|title=The generation and evolution of the continental crust|journal=[[Journal of the Geological Society]]|volume=167|issue=2|year=2010|pages=229–248|doi=10.1144/0016-76492009-072|bibcode=2010JGSoc.167..229H|s2cid=131052922}}
* {{cite journal|last1=Saal|first1=A.L.|last2=Rudnick|first2=R.L.|last3=Ravizza|first3=G.E.|last4=Hart|first4=S.R.|title=Re–Os isotope evidence for the composition, formation and age of the lower continental crust|journal=[[Nature (journal)|Nature]]|year=1998|issue=6680|pages=58–61|doi=10.1038/29966|volume=393|bibcode=1998Natur.393...58S|s2cid=4327383}}
* {{cite book|last=Walther|first=John Victor|title=Essentials of Geochemistry|page=35|publisher=[[Jones & Bartlett]]|year=2005|isbn=978-0-7637-2642-3|url=https://books.google.com/books?id=NmvMrnxtHecC&pg=PA35}} (Diagram entitled "Model of growth of continental crust through time" by {{cite journal|last1=Taylor|first1=S.R.|last2=McLennan|first2=S.M.|year=1995|title=The geochemical evolution of the continental crust|journal=[[Reviews of Geophysics]]|volume=33|issue=2|pages=241–265|doi=10.1029/95RG00262|bibcode=1995RvGeo..33..241T}})
* {{cite book|last1=Taylor|first1=S. Ross|last2=McLennan|first2=Scott|title=Planetary Crusts: Their Composition, Origin and Evolution|date=2009|publisher=[[Cambridge University Press]]|isbn=9780521841863|url=https://books.google.com/books?id=4WAxH-nYGy8C&dq=the+persistent+myth+of+crustal+growth&pg=PA323|access-date=28 June 2022}}
* {{cite journal|last1=von Huene|first1=Roland|last2=Scholl|first2=David W.|title=Observations at convergent margins concerning sediment subduction, subduction erosion, and the growth of continental crust|journal=[[Reviews of Geophysics]]|year=1991|volume=29|issue=3|pages=279–316|doi=10.1029/91RG00969|bibcode=1991RvGeo..29..279V|url=https://zenodo.org/record/1231311}}
{{Refend}}

== External links ==
* [http://www.geo.cornell.edu/geology/classes/geochemdata/CrustalAbundances.html Average composition of continental crust]
* [https://web.archive.org/web/20080908040832/http://quake.wr.usgs.gov/research/structure/CrustalStructure Crust 5.1]
* [http://assets.cambridge.org/052178/2376/excerpt/0521782376_excerpt.htm Evolution of the continental crust]
* [http://cdn.sci-news.com/images/enlarge8/image_9342e-Plate-Tectonics.jpg Continental crust world map]{{Dead link|date=December 2023 |bot=InternetArchiveBot |fix-attempted=yes }}

{{Earthsinterior}}

{{Authority control}}

{{DEFAULTSORT:Continental Crust}}
[[Category:Plate tectonics]]
[[Category:Structure of the Earth]]
[[Category:Earth's crust]]

Latest revision as of 18:46, 12 December 2024

Continental and oceanic crust on the upper mantle

Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust,[1][2] called sima which is richer in magnesium silicate (Mg-Si) minerals. Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity), there is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character.[3]

Most continental crust is dry land above sea level. However, 94% of the Zealandia continental crust region is submerged beneath the Pacific Ocean,[4] with New Zealand constituting 93% of the above-water portion.

Thickness and density

[edit]
The thickness of Earth's crust (km)

The continental crust consists of various layers, with a bulk composition that is intermediate (SiO2 wt% = 60.6).[5] The average density of the continental crust is about, 2.83 g/cm3 (0.102 lb/cu in),[6] less dense than the ultramafic material that makes up the mantle, which has a density of around 3.3 g/cm3 (0.12 lb/cu in). Continental crust is also less dense than oceanic crust, whose density is about 2.9 g/cm3 (0.10 lb/cu in). At 25 to 70 km (16 to 43 mi) in thickness, continental crust is considerably thicker than oceanic crust, which has an average thickness of around 7 to 10 km (4.3 to 6.2 mi). Approximately 41% of Earth's surface area[7][8] and about 70% of the volume of Earth's crust are continental crust.[9]

Importance

[edit]

Because the surface of continental crust mainly lies above sea level, its existence allowed land life to evolve from marine life. Its existence also provides broad expanses of shallow water known as epeiric seas and continental shelves where complex metazoan life could become established during early Paleozoic time, in what is now called the Cambrian explosion.[10]

Origin

[edit]

All continental crust is ultimately derived from mantle-derived melts (mainly basalt) through fractional differentiation of basaltic melt and the assimilation (remelting) of pre-existing continental crust. The relative contributions of these two processes in creating continental crust are debated, but fractional differentiation is thought to play the dominant role.[11] These processes occur primarily at magmatic arcs associated with subduction.

There is little evidence of continental crust prior to 3.5 Ga.[12] About 20% of the continental crust's current volume was formed by 3.0 Ga.[13] There was relatively rapid development on shield areas consisting of continental crust between 3.0 and 2.5 Ga.[12] During this time interval, about 60% of the continental crust's current volume was formed.[13] The remaining 20% has formed during the last 2.5 Ga.

Proponents of a steady-state hypothesis argue that the total volume of continental crust has remained more or less the same after early rapid planetary differentiation of Earth and that presently found age distribution is just the result of the processes leading to the formation of cratons (the parts of the crust clustered in cratons being less likely to be reworked by plate tectonics).[14] However, this is not generally accepted.[15]

Forces at work

[edit]

In contrast to the persistence of continental crust, the size, shape, and number of continents are constantly changing through geologic time. Different tracts rift apart, collide and recoalesce as part of a grand supercontinent cycle.[16]

There are currently about 7 billion cubic kilometres (1.7 billion cubic miles) of continental crust, but this quantity varies because of the nature of the forces involved. The relative permanence of continental crust contrasts with the short life of oceanic crust. Because continental crust is less dense than oceanic crust, when active margins of the two meet in subduction zones, the oceanic crust is typically subducted back into the mantle. Continental crust is rarely subducted (this may occur where continental crustal blocks collide and overthicken, causing deep melting under mountain belts such as the Himalayas or the Alps). For this reason the oldest rocks on Earth are within the cratons or cores of the continents, rather than in repeatedly recycled oceanic crust; the oldest intact crustal fragment is the Acasta Gneiss at 4.01 Ga, whereas the oldest large-scale oceanic crust (located on the Pacific plate offshore of the Kamchatka Peninsula) is from the Jurassic (≈180 Ma), although there might be small older remnants in the Mediterranean Sea at about 340 Ma.[17] Continental crust and the rock layers that lie on and within it are thus the best archive of Earth's history.[8][18]

The height of mountain ranges is usually related to the thickness of crust. This results from the isostasy associated with orogeny (mountain formation). The crust is thickened by the compressive forces related to subduction or continental collision. The buoyancy of the crust forces it upwards, the forces of the collisional stress balanced by gravity and erosion. This forms a keel or mountain root beneath the mountain range, which is where the thickest crust is found.[19] The thinnest continental crust is found in rift zones, where the crust is thinned by detachment faulting and eventually severed, replaced by oceanic crust. The edges of continental fragments formed this way (both sides of the Atlantic Ocean, for example) are termed passive margins.

The high temperatures and pressures at depth, often combined with a long history of complex distortion, cause much of the lower continental crust to be metamorphic – the main exception to this being recent igneous intrusions. Igneous rock may also be "underplated" to the underside of the crust, i.e. adding to the crust by forming a layer immediately beneath it.

Continental crust is produced and (far less often) destroyed mostly by plate tectonic processes, especially at convergent plate boundaries. Additionally, continental crustal material is transferred to oceanic crust by sedimentation. New material can be added to the continents by the partial melting of oceanic crust at subduction zones, causing the lighter material to rise as magma, forming volcanoes. Also, material can be accreted horizontally when volcanic island arcs, seamounts or similar structures collide with the side of the continent as a result of plate tectonic movements. Continental crust is also lost through erosion and sediment subduction, tectonic erosion of forearcs, delamination, and deep subduction of continental crust in collision zones.[20] Many theories of crustal growth are controversial, including rates of crustal growth and recycling, whether the lower crust is recycled differently from the upper crust, and over how much of Earth history plate tectonics has operated and so could be the dominant mode of continental crust formation and destruction.[14]

It is a matter of debate whether the amount of continental crust has been increasing, decreasing, or remaining constant over geological time. One model indicates that at prior to 3.7 Ga ago continental crust constituted less than 10% of the present amount.[21] By 3.0 Ga ago the amount was about 25%, and following a period of rapid crustal evolution it was about 60% of the current amount by 2.6 Ga ago.[22] The growth of continental crust appears to have occurred in spurts of increased activity corresponding to five episodes of increased production through geologic time.[23]

See also

[edit]

References

[edit]
  1. ^ Fairbridge, Rhodes W., ed. (1967). The Encyclopedia of Atmospheric Sciences and Astrogeology. New York: Reinhold Publishing. p. 323. OCLC 430153.
  2. ^ Davis, George H.; Reynolds, Stephen J.; Kluth, Charles F. (2012). "Nature of Structural Geology". Structural Geology of Rocks and Regions (3rd ed.). John Wiley & Sons. p. 18. ISBN 978-0-471-15231-6.
  3. ^ McGuire, Thomas (2005). "Earthquakes and Earth's Interior". Earth Science: The Physical Setting. AMSCO School Publications Inc. pp. 182–184. ISBN 978-0-87720-196-0.
  4. ^ Mortimer, Nick; Campbell, Hamish J. (2017). "Zealandia: Earth's Hidden Continent". GSA Today. 27: 27–35. doi:10.1130/GSATG321A.1. Archived from the original on 17 February 2017.
  5. ^ Rudnick, R.L.; Gao, S. (1 January 2014). "Composition of the Continental Crust". Treatise on Geochemistry. pp. 1–51. doi:10.1016/B978-0-08-095975-7.00301-6. ISBN 9780080983004.
  6. ^ Christensen, Nikolas I.; Mooney, Walter D. (1995). "Seismic velocity structure and composition of the continental crust: A global view". Journal of Geophysical Research: Solid Earth. 100 (B6): 9761–9788. Bibcode:1995JGR...100.9761C. doi:10.1029/95JB00259. ISSN 2156-2202.
  7. ^ Stein, M.; Ben-Avraham, Z. (2015). "Mechanism of Continental Crustal Growth". Treatise on Geophysics. pp. 173–199. doi:10.1016/B978-0-444-53802-4.00159-7. ISBN 9780444538031.
  8. ^ a b Cogley 1984.
  9. ^ Hawkesworth et al. 2010.
  10. ^ Waggoner, Ben; Collins, Allen. "The Cambrian Period". University of California Museum of Paleontology. Retrieved 30 November 2013.
  11. ^ Klein, Benjamin; Jagoutz, Oliver (1 January 2018). "On the importance of crystallization-differentiation for the generation of SiO2-rich melts and the compositional build-up of arc (and continental) crust". American Journal of Science. 318 (1): 29–63. Bibcode:2018AmJS..318...29J. doi:10.2475/01.2018.03. ISSN 1945-452X. S2CID 134674805.
  12. ^ a b Hart, P. J. (1969). Earth's Crust and Upper Mantle. American Geophysical Union. pp. 13–15. ISBN 978-0-87590-013-1.
  13. ^ a b McCann, T. (2008). The Geology of Central Europe: Volume 1: Precambrian and Palaeozoic. London: The Geological Society. p. 22. ISBN 978-1-86239-245-8.
  14. ^ a b Armstrong 1991.
  15. ^ Taylor & McLennan 2009.
  16. ^ Condie 2002.
  17. ^ "World's oldest ocean crust dates back to ancient supercontinent".
  18. ^ Bowring & Williams 1999.
  19. ^ Saal et al. 1998.
  20. ^ Clift & Vannuchi 2004.
  21. ^ von Huene & Scholl 1991.
  22. ^ Taylor & McLennan 1995.
  23. ^ Butler 2011, See graphic.

Bibliography

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