190:
20:
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119:. The sedimentary rocks which may be deposited on top of the basement usually form a relatively thin veneer, but can be more than 5 kilometres (3 mi) thick. The basement rock of the crust can be 32â48 kilometres (20â30 mi) thick or more. The basement rock can be located under layers of sedimentary rock, or be visible at the surface.
167:
The basement rocks of the continental crust tend to be much older than the oceanic crust. The oceanic crust can be from 0â340 million years in age, with an average age of 64 million years. Continental crust is older because continental crust is light and thick enough so it is not subducted,
262:, where the new igneous rock forms a layer on the underside of the crust. The majority of continental crust on the planet is around 1 to 3 billion years old, and it is theorised that there was at least one period of rapid expansion and accretion to the continents during the Precambrian.
308:
Oceanic crust can be subducted, while continental crust cannot. Eventually, the subduction of the underthrusting oceanic crust can bring the volcanic arc close to a continent, with which it may collide. When this happens, instead of being subducted, it is
313:
to the edge of the continent and becomes part of it. Thin strips or fragments of the underthrusting oceanic plate may also remain attached to the edge of the continent so that they are wedged and tilted between the converging plates, creating
48:
are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The basement rocks lie below a
158:
laid from volcanic eruptions, and the granite is the result of magma intrusions into the Vishnu Schist. An extensive cross section of sedimentary rocks laid down on top of it through the ages is visible as well.
258:
was accreted to the edge of the continent. Any of this material may be folded, refolded and metamorphosed. New igneous rock may freshly intrude into the crust from underneath, or may form
341:â blocks of crust built around an initial original core of continents â that gradually grew and expanded as additional newly created terranes were added to their edges. For instance,
281:
When a plate of oceanic crust is subducted beneath an overriding plate of oceanic crust, as the underthrusting crust melts, it causes an upwelling of magma that can cause
835:. Bates, Robert Latimer, 1912-, Jackson, Julia A., 1939-, American Geological Institute. (3rd ed., Anchor books ed.). Garden City, N.Y.: Anchor Press/Doubleday.
545:
898:
329:. Exotic terranes are pieces of other continents that have broken off from their original parent continent and have become accreted to a different continent.
349:. Most continents, such as Asia, Africa and Europe, include several continental cratons, as they were formed by the accretion of many smaller continents.
131:
525:
273:, at subduction fronts, where oceanic crust is being pushed down into the mantle by an overriding plate of oceanic or continental crust.
899:"Western metamorphic and sedimentary basement / New Zealand's Rocks / NZ Geology / Science Topics / Learning / Home - GNS Science"
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As such, the basement rock can become younger going closer to the edge of the continent. There are exceptions, however, such as
729:
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207:
246:. They may consist of many different types of rock â volcanic, intrusive igneous and metamorphic. They may also contain
866:
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265:
Much of the basement rock may have originally been oceanic crust, but it was highly metamorphosed and converted into
229:
79:
Crustal rocks are modified several times before they become basement, and these transitions alter their composition.
520:
861:. Van der Pluijm, Ben A., 1955-, Catacosinos, Paul A., 1933-. Boulder, Colo.: Geological Society of America. 1996.
758:"The Determination of Economic Basement of Rock Formation in Exploring the LangkatâMedan Area, North Sumatra Basin"
531:
387:
was able to move over the hard basement, making the distinction between basement and cover even more pronounced.
322:
are accreted to their edges, and so continents can be composed of a complex quilt of terranes of varying ages.
211:
740:
757:
430:
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890:
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include
Proterozoic, Paleozoic and Mesozoic age rocks for the Oaxaquia, the Mixteco and the Guerrero
305:
from volcanoes. This tends to make the crust thicker and less dense, making it immune to subduction.
785:
200:
476:
is also used to describe the deeper parts of a cover sequence that are of no economic interest.
745:
Search and
Discovery Article #40052 (adapted from: AAPG Explorer (November and December, 1999)
925:
772:
380:
259:
700:
Geological
Society of London, 2007, Ch. 2 Metamorphic and Igneous Basement Complexes, p. 5,
583:
Seton, M; MĂŒller, RD; Zahirovic, S; Williams, S; Wright, NM; Cannon, J; et al. (2020).
76:
or sedimentary rocks on top of the basement can be called a "cover" or "sedimentary cover".
596:
423:
8:
310:
111:
which are laid down on top of the basement rocks after the continent was formed, such as
600:
585:"A global data set of present-day oceanic crustal age and seafloor spreading parameters"
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Mapping
Geologic Structure of Basement and Role of Basement in Hydrocarbon Entrapment,
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The basement rocks are often highly metamorphosed and complex, and are usually
142:). The Vishnu Schist is believed to be highly metamorphosed igneous rocks and
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along the subduction front on the overriding plate. This produces an oceanic
251:
139:
50:
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123:
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consisted of most of the Earth's continents being accreted into one giant
608:
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720:, Ch 5, in Susana A. Alaniz-Ălvarez and Angel F. Nieto-Samaniego, eds.,
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214: in this section. Unsourced material may be challenged and removed.
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Geological
Society of America Special Paper 422, 2007, pp. 142â145
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Metamorphic or igneous rocks below a sedimentary platform or cover
491:
488: â Large stable area of exposed Precambrian crystalline rock
442:
366:
319:
269:. It is possible for oceanic crust to be subducted down into the
255:
127:
104:
37:
26:
464:) crystalline basement is not of interest as it rarely contains
448:
The term basement is used mostly in disciplines of geology like
642:
Structural
Geology and Tectonics. Encyclopedia of Earth Science
527:
Map Shows
Content and Origins of the Nationâs Geologic Basement
434:
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while oceanic crust is periodically subducted and replaced at
87:
Basement rock is the thick foundation of ancient, and oldest,
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301:, and thickens the crust by depositing additional layers of
122:
Basement rock is visible, for example, at the bottom of the
173:
155:
151:
361:, the basement generally refers to rocks older than the
718:
Igneous petrogenesis of the Trans-Mexican
Volcanic Belt
318:. In this manner, continents can grow over time as new
716:
A. GĂłmez-Tuena, Ma.T. Orozco-Esquivel, and L. Ferrari
414:) rock units as the basement to the late Mesozoic and
831:Bates, Robert L.; Jackson, Julia A., eds. (1984).
418:Andean sequences developed following the onset of
755:
917:
805:McGraw-Hill dictionary of geology and mineralogy
644:. Berlin, Heidelberg: Springer. pp. 26â29.
749:
494: â Solid rock under loose surface material
383:zone on which the harder (stronger) limestone
337:Continents can consist of several continental
859:Basement and basins of eastern North America
830:
126:, consisting of 1.7- to 2-billion-year-old
107:. Basement rock is contrasted to overlying
56:or cover, or more generally any rock below
616:
254:that became wedged between plates when a
230:Learn how and when to remove this message
379:were deposited. The evaporites formed a
18:
807:(2nd ed.). New York: McGraw-Hill.
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510:
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589:Geochemistry, Geophysics, Geosystems
212:adding citations to reliable sources
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82:
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394:geology the basement refers to the
13:
14:
937:
640:Burwash, RA (1987). "Basement".
570:"Basement domain list by region"
519: This article incorporates
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422:along the western margin of the
365:. On top of this older basement
188:
72:in origin. In the same way, the
532:United States Geological Survey
199:needs additional citations for
833:Dictionary of geological terms
803:Parker, Sybil P., ed. (2003).
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546:"Bedrock | Encyclopedia.com"
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756:Mulhadiano J.A.S. (1984).
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250:, which are fragments of
460:in which the (typically
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293:. This volcanism causes
696:Teresa Moreno, et al.,
678:Encyclopedia Britannica
650:10.1007/3-540-31080-0_6
103:, often in the form of
889:: CS1 maint: others (
780:Cite journal requires
521:public domain material
303:extrusive igneous rock
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33:
698:The geology of Chile,
674:"Volcanism | geology"
595:(10): e2020GC009214.
22:
609:10.1029/2020GC009214
550:www.encyclopedia.com
429:When discussing the
424:South American Plate
208:improve this article
46:crystalline basement
741:Gay, Parker (2002)
601:2020GGG....2109214S
722:Geology of MĂ©xico,
299:igneous intrusions
62:sedimentary basins
34:
730:978-0-8137-2422-5
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534:. April 23, 2015.
474:economic basement
458:petroleum geology
267:continental crust
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109:sedimentary rocks
83:Continental crust
58:sedimentary rocks
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906:. Retrieved
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295:metamorphism
287:volcanic arc
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260:underplating
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220:January 2019
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206:Please help
201:verification
198:
166:
124:Grand Canyon
121:
93:igneous rock
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618:1885/289849
472:. The term
470:natural gas
462:Precambrian
396:Proterozoic
244:crystalline
89:metamorphic
66:metamorphic
51:sedimentary
908:2019-12-26
764:2019-04-09
683:2019-04-09
555:2019-04-09
499:References
420:subduction
402:and early
377:limestones
370:evaporites
316:ophiolites
248:ophiolites
180:Complexity
170:subduction
101:continents
885:cite book
627:224967179
466:petroleum
400:Paleozoic
283:volcanism
277:Volcanism
117:limestone
113:sandstone
74:sediments
64:that are
920:Category
877:35068112
823:50731349
480:See also
443:terranes
439:basement
416:Cenozoic
412:Jurassic
408:Triassic
404:Mesozoic
374:Mesozoic
320:terranes
311:accreted
54:platform
42:basement
31:Scotland
851:9412868
797:Sources
597:Bibcode
572:. USGS.
492:Bedrock
367:Permian
339:cratons
333:Cratons
289:, like
256:terrane
176:areas.
146:, from
128:granite
105:granite
70:igneous
38:geology
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523:from
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291:Japan
144:shale
97:crust
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863:ISBN
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702:ISBN
654:ISBN
456:and
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