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Ultra-high-pressure metamorphism

February 22, 2023

Ultra-high-pressure metamorphism refers to metamorphic processes at pressures high enough to stabilize coesite, the high-pressure polymorph of SiO2. It is important because the processes that form and exhume ultra-high-pressure (UHP) metamorphic rocks may strongly affect plate tectonics, the composition and evolution of Earth's crust. The discovery of UHP metamorphic rocks in 1984[1][2] revolutionized our understanding of plate tectonics. Prior to 1984 there was little suspicion that continental rocks could reach such high pressures.

The formation of many UHP terrains has been attributed to the subduction of microcontinents or continental margins and the exhumation of all UHP terrains has been ascribed principally to buoyancy caused by the low density of continental crust—even at UHP—relative to Earth's mantle. While the subduction proceeds at low thermal gradients of less than 10°C/km, the exhumation proceeds at elevated thermal gradients of 10-30°C/km.

Definition

Metamorphism of rocks at pressures ≥27kbar (2.7GPa) to stabilize coesite, the high-pressure polymorph of SiO2, recognized by either the presence of a diagnostic mineral (e.g., coesite or diamond[3]), mineral assemblage (e.g., magnesite + aragonite[4]), or mineral compositions.

Identification

Petrological indicators of UHP metamorphism are usually preserved in eclogite. The presence of metamorphic coesite, diamond, or majoritic garnet are diagnostic; other potential mineralogical indicators of UHP metamorphism, such as alpha-PbO2 structured TiO2, are not widely accepted. Mineral assemblages, rather than single minerals, can also be used to identify UHP rocks; these assemblages include magnesite + aragonite.[4] Because minerals change composition in response to changes in pressure and temperature, mineral compositions can be used to calculate pressure and temperature; for UHP eclogite the best geobarometers involve garnet + clinopyroxene + K-white mica and garnet + clinopyroxene + kyanite + coesite/quartz.[5] Most UHP rocks were metamorphosed at peak conditions of 800 °C and 3 GPa.[6] At least two UHP localities record higher temperatures: the Bohemian and Kokchetav Massifs reached 1000–1200 °C at pressures of at least 4 GPa.[7][8][9]

Most felsic UHP rocks have undergone extensive retrograde metamorphism and preserve little or no UHP record. Commonly, only a few eclogite enclaves or UHP minerals reveal that the entire terrain was subducted to mantle depths. Many granulite terrains and even batholithic rocks may have undergone UHP metamorphism that was subsequently obliterated[10][11]

Global distribution

Geologists have identified UHP terrains at more than twenty localities around the globe in most well-studied Phanerozoic continental orogenic belts; most occur in Eurasia.[12] Coesite is relatively widespread, diamond less so, and majoritic garnet is known from only rare localities. The oldest UHP terrain is 620 Ma and is exposed in Mali;[13] the youngest is 8 Ma and exposed in the D'Entrecasteaux Islands of Papua New Guinea.[14] A modest number of continental orogens have undergone multiple UHP episodes.[15]

UHP terrains vary greatly in size, from the >30,000 km2 giant UHP terrains in Norway and China, to small kilometer-scale bodies.[16] The giant UHP terrains have a metamorphic history spanning tens of millions of years, whereas the small UHP terrains have a metamorphic history spanning millions of years.[17] All are dominated by quartzofeldspathic gneiss with a few percent mafic rock (eclogite) or ultramafic rock (garnet-bearing peridotite). Some include sedimentary or rift-volcanic sequences that have been interpreted as passive margins prior to metamorphism.[18][19]

Implications and importance

UHP rocks record pressures greater than those that prevail within Earth's crust. Earth's crust is a maximum of 70–80 km thickness, and pressures at the base are <2.7 GPa for typical crustal densities. UHP rocks therefore come from depths within Earth's mantle. UHP rocks of a wide variety of compositions have been identified as both regional metamorphic terrains and xenoliths.

UHP ultramafic xenoliths of mantle affinity provide information (e.g., mineralogy or deformation mechanisms) about processes active deep in Earth. UHP xenoliths of crustal affinity provide information about processes active deep in Earth, but also information about what kinds of crustal rocks reach great depth in Earth and how profound those depths are.

Regional metamorphic UHP terrains exposed on Earth's surface provide considerable information that is not available from xenoliths. Integrated study by structural geologists, petrologists, and geochronologists has provided considerable data on how the rocks deformed, the pressures and temperatures of metamorphism, and how the deformation and metamorphism varied as a function of space and time. It has been postulated that small UHP terrains that underwent short periods of metamorphism formed early during continent subduction, whereas giant UHP terrains that underwent long periods of metamorphism formed late during continent collision.[17]

Formation of UHP rocks

Eclogite-facies HP to UHP metamorphic rocks are produced by subduction of crustal rocks to the lower crust to mantle depths for extreme metamorphism at the low thermal gradients of less than 10°C/km.[20] All of these rocks occur at convergent plate margins, and UHP rocks only occur in collisional orogens. There is general agreement that most well-exposed and well-studied UHP terrains were produced by the burial of crustal rocks to mantle depths of >80 km during subduction. Continental margin subduction is well documented in a number of collisional orogens, such as the Dabie orogen where South China Block passive-margin sedimentary and volcanic sequences are preserved,[21] in the Arabian continental margin beneath the Samail ophiolite (in the Al Hajar Mountains, Oman),[22] and in the Australian margin presently subducting beneath the Banda Arc.[23] Sediment subduction occurs beneath volcanoplutonic arcs around the world[24] and is recognized in the compositions of arc lavas.[25] Continental subduction may be underway beneath the Pamir.[26] Subduction erosion also occurs beneath volcanoplutonic arcs around the world,[24] carrying continental rocks to mantle depths at least locally.[27]

Exhumation of UHP rocks

The specific processes by which UHP terrains were exhumed to Earth's surface appear to have been different in different locations.

If continental lithosphere is subducted because of its attachment to downgoing oceanic lithosphere, the downward slab pull force may exceed the strength of the slab at some time and location, and necking of the slab initiates.[28] The positive buoyancy of the continental slab—in opposition principally to ridge push—can then drive exhumation of the subducting crust at a rate and mode determined by plate geometry and the rheology of the crustal materials. The Norwegian Western Gneiss Region is the archetype for this exhumation mode, which has been termed 'eduction' or subduction inversion.[29]

If a plate undergoing subduction inversion begins to rotate in response to changing boundary conditions or body forces, the rotation may exhume UHP rocks toward crustal levels. This could occur if, for example, the plate is small enough that continental subduction markedly changes the orientation and magnitude of slab pull or if the plate is being consumed by more than one subduction zone pulling in different directions.[30] Such a model has also been proposed for the UHP terrain in eastern Papua New Guinea, where rotation of the Woodlark microplate is causing a rift in the Woodlark Basin).[31]

If a subducting plate consists of a weak buoyant layer atop a stronger negatively buoyant layer, the former will detach at the depth where the buoyancy force exceeds slab pull, and extrude upward as a semi-coherent sheet. This type of delamination and stacking was proposed to explain exhumation of UHP rocks in the Dora Maira massif in Piedmont, Italy,[32] in the Dabie orogen,[33] and in the Himalaya.[34] In addition it was demonstrated with analogue experiments.[35] This mechanism is different from flow in a subduction channel in that the exhuming sheet is strong and remains undeformed. A variant of this mechanism, in which the exhuming material undergoes folding, but not wholescale disruption, was suggested for the Dabie orogen, where exhumation-related stretching lineations and gradients in metamorphic pressure indicate rotation of the exhuming block;[36]

The buoyancy of a microcontinent locally slows the rollback of and steepens the dip of subducting mafic lithosphere.[37] If the mafic lithosphere on either side of the microcontinent continues to roll back, a buoyant portion of the microcontinent may detach, allowing the retarded portion of the mafic slab to roll quickly back, making room for the UHP continental crust to exhume and driving back-arc extension. This model was developed to explain repeated cycles of subduction and exhumation documented in the Aegean and Calabria–Apennine orogens. UHP exhumation by slab rollback has not yet been extensively explored numerically, but it has been reproduced in numerical experiments of Apennine-style collisions.[38]

If continental material is subducted within a confined channel, the material tends to undergo circulation driven by tractions along the base of the channel and the relative buoyancy of rocks inside the channel;[39] the flow can be complex, generating nappe-like or chaotically mixed bodies.[40][41][42][43][44][45] The material within the channel can be exhumed if:[41][42]

  1. continuous introduction of new material into the channel driven by traction of the subducting plate pushes old channel material upward;
  2. buoyancy in the channel exceeds subduction-related traction and the channel is pushed upward by the asthenospheric mantle intruding between the plates; or
  3. a strong indenter squeezes the channel and extrudes the material within.

Buoyancy alone is unlikely to drive exhumation of UHP rocks to Earth's surface, except in oceanic subduction zones.[46] Arrest and spreading of UHP rocks at the Moho (if the overlying plate is continental) is likely unless other forces are available to force the UHP rocks upward.[11] Some UHP terrains might be coalesced material derived from subduction erosion.[47][48] This model was suggested to explain the North Qaidam UHP terrain in western China.[49] Even subducted sediment may rise as diapirs from the subducting plate and accumulate to form UHP terrains.[50][51]

Studies of numerical geodynamics suggest that both subducted sediment and crystalline rocks may rise through the mantle wedge diapirically to form UHP terranes.[47][49][50] Diapiric rise of a much larger subducted continental body has been invoked to explain the exhumation of the Papua New Guinea UHP terrain.[52] This mechanism was alo used to explain the exhumation of UHP rocks in Greenland.[53] However, the mantle wedge above continental subduction zones is cold like cratons, which do not allow for diapirically ascending of the crustal materials. Foundering of the gravitationally unstable portions of continental lithosphere locally carries quartzofeldspathic rocks into the mantle[54] and may be ongoing beneath the Pamir.[26]

See also

References

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  2. ^ Smith, D. C., 1984, Coesite in clinopyroxene in the Caledonides and its implications for geodynamics: Nature, v. 310, p. 641–644.
  3. ^ Massonne, H. J., and Nasdala, L., 2000, Microdiamonds from the Saxonian Erzgebirge, Germany: in situ micro-Raman characterisation: European Journal of Mineralogy, v. 12, p. 495-498.
  4. ^ a b Klemd, R., Lifei, Z., Ellis, D., Williams, S., and Wenbo, J., 2003, Ultrahigh-pressure metamorphism in eclogites from the western Tianshan high-pressure belt (Xinjiang, western China); discussion and reply: American Mineralogist, v. 88, p. 1153-1160
  5. ^ Ravna, E. J. K., and Terry, M. P., 2004, Geothermobarometry of phengite-kyanite-quartz/coesite eclogites: Journal of Metamorphic Geology, v. 22, p. 579-592.
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  7. ^ Massonne, H.-J., 2003, A comparison of the evolution of diamondiferous quartz-rich rocks from the Saxonian Erzgebirge and the Kokchetav Massif: are so-called diamondiferous gneisses magmatic rocks?: Earth and Planetary Science Letters, v. 216, p. 347–364.
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  28. ^ van Hunen, J., and Allen, M. B., 2011, Continental collision and slab break-off: A comparison of 3-D numerical models with observations: Earth and Planetary Science Letters, v. 302, p. 27-37.
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  30. ^ Guo, Xiaoyu; Encarnacion, John; Xu, Xiao; Deino, Alan; Li, Zhiwu; Tian, Xiaobo (2012-10-01). "Collision and rotation of the South China block and their role in the formation and exhumation of ultrahigh pressure rocks in the Dabie Shan orogen". Terra Nova. 24 (5): 339–350. Bibcode:2012TeNov..24..339G. doi:10.1111/j.1365-3121.2012.01072.x. ISSN 1365-3121. S2CID 128133726.
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  37. ^ Brun, J.-P., and Faccenna, C., 2008, Exhumation of high-pressure rocks driven by slab rollback: Earth and Planetary Science Letters, v. 272, p. 1-7.
  38. ^ Faccenda, M., Gerya, T. V., and Burlini, L., 2009, Deep slab hydration induced by bending-related variations in tectonic pressure: Nature Geoscience, v. DOI: 10.1038/NGEO656.
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  42. ^ a b Warren, C. J., Beaumont, C., and Jamieson, R. A., 2008, Modelling tectonic styles and ultrahigh pressure (UHP) rock exhumation during the transition from oceanic subduction to continental collision: Earth and Planetary Science Letters, v. 267, p. 129-145.
  43. ^ Yamato, P., Burov, E., Agard, P., Pourhiet, L. L., and Jolivet, L., 2008, HP-UHP exhumation during slow continental subduction: Self-consistent thermodynamically and thermomechanically coupled model with application to the Western Alps: Earth and Planetary Science Letters, v. 271, p. 63-74.
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  46. ^ Hacker, B.R., 2007. Ascent of the ultrahigh-pressure Western Gneiss Region, Norway. In Cloos, M., Carlson, W.D., Gilbert, M.C., Liou, J.G., and Sorenson, S.S., eds., Convergent Margin Terranes and Associated Regions: A Tribute to W.G. Ernst: Geological Society of America Special Paper 419, p. 171–184.
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Further reading

  • Coleman, R.G., and Wang, X. (Editors), 1995. Ultrahigh Pressure Metamorphism. Cambridge University Press, 528 pp.
  • Hacker, B.R., and Liou, J.G. (Editors), 1998. When Continents Collide: Geodynamics and Geochemistry of Ultrahigh-Pressure Rocks. Kluwer Academic Publishers, 323 pp.
  • Liou, J.G., and Ernst, W.G. (Editors), 2000. UltraHigh Pressure Metamorphism and Geodynamics in Collision-Type Orogenic Belts. Geological Society of America, International Book Series, volume 4, 293 pp.
  • Hacker, B.R., McClelland, W.C., and Liou, J.G. (Editors), 2006. Ultrahigh-Pressure Metamorphism: Deep Continental Subduction. Geological Society of America Special Paper 403, 206 pp.

February 22, 2023
ultra, high, pressure, metamorphism, refers, metamorphic, processes, pressures, high, enough, stabilize, coesite, high, pressure, polymorph, sio2, important, because, processes, that, form, exhume, ultra, high, pressure, metamorphic, rocks, strongly, affect, p. Ultra high pressure metamorphism refers to metamorphic processes at pressures high enough to stabilize coesite the high pressure polymorph of SiO2 It is important because the processes that form and exhume ultra high pressure UHP metamorphic rocks may strongly affect plate tectonics the composition and evolution of Earth s crust The discovery of UHP metamorphic rocks in 1984 1 2 revolutionized our understanding of plate tectonics Prior to 1984 there was little suspicion that continental rocks could reach such high pressures The formation of many UHP terrains has been attributed to the subduction of microcontinents or continental margins and the exhumation of all UHP terrains has been ascribed principally to buoyancy caused by the low density of continental crust even at UHP relative to Earth s mantle While the subduction proceeds at low thermal gradients of less than 10 C km the exhumation proceeds at elevated thermal gradients of 10 30 C km Contents 1 Definition 2 Identification 3 Global distribution 4 Implications and importance 4 1 Formation of UHP rocks 4 2 Exhumation of UHP rocks 5 See also 6 References 7 Further readingDefinition EditMetamorphism of rocks at pressures 27kbar 2 7GPa to stabilize coesite the high pressure polymorph of SiO2 recognized by either the presence of a diagnostic mineral e g coesite or diamond 3 mineral assemblage e g magnesite aragonite 4 or mineral compositions Identification EditPetrological indicators of UHP metamorphism are usually preserved in eclogite The presence of metamorphic coesite diamond or majoritic garnet are diagnostic other potential mineralogical indicators of UHP metamorphism such as alpha PbO2 structured TiO2 are not widely accepted Mineral assemblages rather than single minerals can also be used to identify UHP rocks these assemblages include magnesite aragonite 4 Because minerals change composition in response to changes in pressure and temperature mineral compositions can be used to calculate pressure and temperature for UHP eclogite the best geobarometers involve garnet clinopyroxene K white mica and garnet clinopyroxene kyanite coesite quartz 5 Most UHP rocks were metamorphosed at peak conditions of 800 C and 3 GPa 6 At least two UHP localities record higher temperatures the Bohemian and Kokchetav Massifs reached 1000 1200 C at pressures of at least 4 GPa 7 8 9 Most felsic UHP rocks have undergone extensive retrograde metamorphism and preserve little or no UHP record Commonly only a few eclogite enclaves or UHP minerals reveal that the entire terrain was subducted to mantle depths Many granulite terrains and even batholithic rocks may have undergone UHP metamorphism that was subsequently obliterated 10 11 Global distribution EditGeologists have identified UHP terrains at more than twenty localities around the globe in most well studied Phanerozoic continental orogenic belts most occur in Eurasia 12 Coesite is relatively widespread diamond less so and majoritic garnet is known from only rare localities The oldest UHP terrain is 620 Ma and is exposed in Mali 13 the youngest is 8 Ma and exposed in the D Entrecasteaux Islands of Papua New Guinea 14 A modest number of continental orogens have undergone multiple UHP episodes 15 UHP terrains vary greatly in size from the gt 30 000 km2 giant UHP terrains in Norway and China to small kilometer scale bodies 16 The giant UHP terrains have a metamorphic history spanning tens of millions of years whereas the small UHP terrains have a metamorphic history spanning millions of years 17 All are dominated by quartzofeldspathic gneiss with a few percent mafic rock eclogite or ultramafic rock garnet bearing peridotite Some include sedimentary or rift volcanic sequences that have been interpreted as passive margins prior to metamorphism 18 19 Implications and importance EditUHP rocks record pressures greater than those that prevail within Earth s crust Earth s crust is a maximum of 70 80 km thickness and pressures at the base are lt 2 7 GPa for typical crustal densities UHP rocks therefore come from depths within Earth s mantle UHP rocks of a wide variety of compositions have been identified as both regional metamorphic terrains and xenoliths UHP ultramafic xenoliths of mantle affinity provide information e g mineralogy or deformation mechanisms about processes active deep in Earth UHP xenoliths of crustal affinity provide information about processes active deep in Earth but also information about what kinds of crustal rocks reach great depth in Earth and how profound those depths are Regional metamorphic UHP terrains exposed on Earth s surface provide considerable information that is not available from xenoliths Integrated study by structural geologists petrologists and geochronologists has provided considerable data on how the rocks deformed the pressures and temperatures of metamorphism and how the deformation and metamorphism varied as a function of space and time It has been postulated that small UHP terrains that underwent short periods of metamorphism formed early during continent subduction whereas giant UHP terrains that underwent long periods of metamorphism formed late during continent collision 17 Formation of UHP rocks Edit Eclogite facies HP to UHP metamorphic rocks are produced by subduction of crustal rocks to the lower crust to mantle depths for extreme metamorphism at the low thermal gradients of less than 10 C km 20 All of these rocks occur at convergent plate margins and UHP rocks only occur in collisional orogens There is general agreement that most well exposed and well studied UHP terrains were produced by the burial of crustal rocks to mantle depths of gt 80 km during subduction Continental margin subduction is well documented in a number of collisional orogens such as the Dabie orogen where South China Block passive margin sedimentary and volcanic sequences are preserved 21 in the Arabian continental margin beneath the Samail ophiolite in the Al Hajar Mountains Oman 22 and in the Australian margin presently subducting beneath the Banda Arc 23 Sediment subduction occurs beneath volcanoplutonic arcs around the world 24 and is recognized in the compositions of arc lavas 25 Continental subduction may be underway beneath the Pamir 26 Subduction erosion also occurs beneath volcanoplutonic arcs around the world 24 carrying continental rocks to mantle depths at least locally 27 Exhumation of UHP rocks Edit The specific processes by which UHP terrains were exhumed to Earth s surface appear to have been different in different locations If continental lithosphere is subducted because of its attachment to downgoing oceanic lithosphere the downward slab pull force may exceed the strength of the slab at some time and location and necking of the slab initiates 28 The positive buoyancy of the continental slab in opposition principally to ridge push can then drive exhumation of the subducting crust at a rate and mode determined by plate geometry and the rheology of the crustal materials The Norwegian Western Gneiss Region is the archetype for this exhumation mode which has been termed eduction or subduction inversion 29 If a plate undergoing subduction inversion begins to rotate in response to changing boundary conditions or body forces the rotation may exhume UHP rocks toward crustal levels This could occur if for example the plate is small enough that continental subduction markedly changes the orientation and magnitude of slab pull or if the plate is being consumed by more than one subduction zone pulling in different directions 30 Such a model has also been proposed for the UHP terrain in eastern Papua New Guinea where rotation of the Woodlark microplate is causing a rift in the Woodlark Basin 31 If a subducting plate consists of a weak buoyant layer atop a stronger negatively buoyant layer the former will detach at the depth where the buoyancy force exceeds slab pull and extrude upward as a semi coherent sheet This type of delamination and stacking was proposed to explain exhumation of UHP rocks in the Dora Maira massif in Piedmont Italy 32 in the Dabie orogen 33 and in the Himalaya 34 In addition it was demonstrated with analogue experiments 35 This mechanism is different from flow in a subduction channel in that the exhuming sheet is strong and remains undeformed A variant of this mechanism in which the exhuming material undergoes folding but not wholescale disruption was suggested for the Dabie orogen where exhumation related stretching lineations and gradients in metamorphic pressure indicate rotation of the exhuming block 36 The buoyancy of a microcontinent locally slows the rollback of and steepens the dip of subducting mafic lithosphere 37 If the mafic lithosphere on either side of the microcontinent continues to roll back a buoyant portion of the microcontinent may detach allowing the retarded portion of the mafic slab to roll quickly back making room for the UHP continental crust to exhume and driving back arc extension This model was developed to explain repeated cycles of subduction and exhumation documented in the Aegean and Calabria Apennine orogens UHP exhumation by slab rollback has not yet been extensively explored numerically but it has been reproduced in numerical experiments of Apennine style collisions 38 If continental material is subducted within a confined channel the material tends to undergo circulation driven by tractions along the base of the channel and the relative buoyancy of rocks inside the channel 39 the flow can be complex generating nappe like or chaotically mixed bodies 40 41 42 43 44 45 The material within the channel can be exhumed if 41 42 continuous introduction of new material into the channel driven by traction of the subducting plate pushes old channel material upward buoyancy in the channel exceeds subduction related traction and the channel is pushed upward by the asthenospheric mantle intruding between the plates or a strong indenter squeezes the channel and extrudes the material within Buoyancy alone is unlikely to drive exhumation of UHP rocks to Earth s surface except in oceanic subduction zones 46 Arrest and spreading of UHP rocks at the Moho if the overlying plate is continental is likely unless other forces are available to force the UHP rocks upward 11 Some UHP terrains might be coalesced material derived from subduction erosion 47 48 This model was suggested to explain the North Qaidam UHP terrain in western China 49 Even subducted sediment may rise as diapirs from the subducting plate and accumulate to form UHP terrains 50 51 Studies of numerical geodynamics suggest that both subducted sediment and crystalline rocks may rise through the mantle wedge diapirically to form UHP terranes 47 49 50 Diapiric rise of a much larger subducted continental body has been invoked to explain the exhumation of the Papua New Guinea UHP terrain 52 This mechanism was alo used to explain the exhumation of UHP rocks in Greenland 53 However the mantle wedge above continental subduction zones is cold like cratons which do not allow for diapirically ascending of the crustal materials Foundering of the gravitationally unstable portions of continental lithosphere locally carries quartzofeldspathic rocks into the mantle 54 and may be ongoing beneath the Pamir 26 See also EditHigh pressure terranes along the Bangong Nujiang Suture Zone Eclogitization Subduction zone metamorphismReferences Edit Chopin C 1984 Coesite and pure pyrope in high grade blueschists of the western Alps a first record and some consequences Contributions to Mineralogy and Petrology v 86 p 107 118 Smith D C 1984 Coesite in clinopyroxene in the Caledonides and its implications for geodynamics Nature v 310 p 641 644 Massonne H J and Nasdala L 2000 Microdiamonds from the Saxonian Erzgebirge Germany in situ micro Raman characterisation European Journal of Mineralogy v 12 p 495 498 a b Klemd R Lifei Z Ellis D Williams S and Wenbo J 2003 Ultrahigh pressure 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convergent plate margins Journal of Asian Earth Sciences v 145 p 46 73 Schmid R Romer R L Franz L Oberhansli R and Martinotti G 2003 Basement Cover Sequences within the UHP unit of the Dabie Shan Journal of Metamorphic Geology v 21 p 531 538 Searle M P Waters D J Martin H N and Rex D C 1994 Structure and metamorphism of blueschist eclogite facies rocks from the northeastern Oman Mountains Journal of the Geological Society of London v 151 p 555 576 Hamilton W 1979 Tectonics of the Indonesian Region U S Geological Survey Professional Paper v 1078 p 1 345 a b Scholl D W and von Huene R 2007 Crustal recycling at modern subduction zones applied to the past Issues of growth and preservation of continental basement mantle geochemistry and supercontinent reconstruction in Robert D Hatcher J Carlson M P McBride J H and Catalan J R M eds Geological Society of America Memoir Boulder Geological Society of America p 9 32 Plank T and Langmuir C H 1993 Tracing trace elements from sediment input to 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Collision and rotation of the South China block and their role in the formation and exhumation of ultrahigh pressure rocks in the Dabie Shan orogen Terra Nova 24 5 339 350 Bibcode 2012TeNov 24 339G doi 10 1111 j 1365 3121 2012 01072 x ISSN 1365 3121 S2CID 128133726 Webb L E Baldwin S L Little T A Fitzgerald P G 2008 Can microplate rotation drive subduction inversion PDF Geology 36 10 823 826 Bibcode 2008Geo 36 823W doi 10 1130 G25134A 1 Chopin C 1987 Very high pressure metamorphism in the western Alps implications for subduction of continental crust Philosophical Transactions of the Royal Society A Mathematical Physical And Engineering Sciences v 321 p 183 197 Okay A I and Sengor A M C 1992 Evidence for intracontinental thrust related exhumation of the ultrahigh pressure rocks in China Geology v 20 p 411 414 Wilke F D H et al 2010 Multi stage reaction history in different eclogite types from the Pakistan Himalaya and implications for exhumation processes Lithos v 114 p 70 85 Chemenda A I Mattauer M Malavieille J and Bokun A N 1995 A mechanism for syn collisional rock exhumation and associated normal faulting Results from physical modelling Earth and Planetary Science Letters v 132 p 225 232 Hacker B R Ratschbacher L Webb L E McWilliams M Ireland T R Calvert A Dong S Wenk H R and Chateigner D 2000 Exhumation of ultrahigh pressure continental crust in east central China Late Triassic Early Jurassic tectonic unroofing Journal of Geophysical Research v 105 p 13339 13364 Brun J P and Faccenna C 2008 Exhumation of high pressure rocks driven by slab rollback Earth and Planetary Science Letters v 272 p 1 7 Faccenda M Gerya T V and Burlini L 2009 Deep slab hydration induced by bending related variations in tectonic pressure Nature Geoscience v DOI 10 1038 NGEO656 Zheng Y F Zhao Z F Chen Y X 2013 Continental subduction channel processes Plate interface interaction during continental collision Chinese Science Bulletin 58 4371 4377 Burov E Jolivet L Le Pourhiet L and Poliakov A 2001 A thermomechanical model of exhumation of high pressure HP and ultrahigh pressure UHP metamorphic rocks in Alpine type collision belts Tectonophysics v 342 p 113 136 a b Gerya T V Perchuk L L and Burg J P 2007 Transient hot channels perpetrating and regurgitating ultrahigh pressure high temperature crust mantle associations in collision belts Lithos v 103 p 236 256 a b Warren C J Beaumont C and Jamieson R A 2008 Modelling tectonic styles and ultrahigh pressure UHP rock exhumation during the transition from oceanic subduction to continental collision Earth and Planetary Science Letters v 267 p 129 145 Yamato P Burov E Agard P Pourhiet L L and Jolivet L 2008 HP UHP exhumation during slow continental subduction Self consistent thermodynamically and thermomechanically coupled model with application to the Western Alps Earth and Planetary Science Letters v 271 p 63 74 Beaumont C Jamieson R A Butler J P and Warren C J 2009 Crustal structure A key constraint on the mechanism of ultrahigh pressure rock exhumation Earth and Planetary Science Letters v 287 p 116 129 Li Z and Gerya T V 2009 Polyphase formation and exhumation of high to ultrahigh pressure rocks in continental subduction zone numerical modeling and application to the Sulu ultrahigh pressure terrane in eastern China Journal of Geophysical Research v 114 Hacker B R 2007 Ascent of the ultrahigh pressure Western Gneiss Region Norway In Cloos M Carlson W D Gilbert M C Liou J G and Sorenson S S eds Convergent Margin Terranes and Associated Regions A Tribute to W G Ernst Geological Society of America Special Paper 419 p 171 184 a b Stockhert B and Gerya T V 2005 Pre collisional high pressure metamorphism and nappe tectonics at active continental margins a numerical simulation Terra Nova v 17 p 102 110 Gerya T V and Stockhert B 2006 Two dimensional numerical modeling of tectonic and metamorphic histories at active continental margins International Journal of Earth Sciences v 95 p 250 274 a b Yin A Manning C E Lovera O Menold C A Chen X and Gehrels G E 2007 Early Paleozoic tectonic and thermomechanical evolution of ultrahigh pressure UHP metamorphic rocks in the northern Tibetan Plateau northwest China International Geology Review v 49 p 681 716 a b Behn M D Kelemen P B Hirth G Hacker B R and Massonne H J 2011 Diapirs as the source of the sediment signature in arc lavas Nature Geoscience v DOI 10 1038 NGEO1214 Currie C A Beaumont C and Huismans R S 2007 The fate of subducted sediments A case for backarc intrusion and underplating Geology v 35 p 1111 1114 Little T A Hacker B R Gordon S M Baldwin S L Fitzgerald P G Ellis S and Korchinski M 2011 Diapiric Exhumation of Earth s youngest UHP eclogites in the gneiss domes of the D Entrecasteaux Islands Papua New Guinea Tectonophysics v 510 p 39 68 Gilotti J A and McClelland W C 2007 Characteristics of and a Tectonic Model for Ultrahigh Pressure Metamorphism in the Overriding Plate of the Caledonian Orogen International Geology Review v 49 p 777 797 Gerya T V and Meilick F I 2011 Geodynamic regimes of subduction under an active margin effects of rheological weakening by fluids and melts Journal of Metamorphic Geology v 29 p 7 31 Further reading EditColeman R G and Wang X Editors 1995 Ultrahigh Pressure Metamorphism Cambridge University Press 528 pp Hacker B R and Liou J G Editors 1998 When Continents Collide Geodynamics and Geochemistry of Ultrahigh Pressure Rocks Kluwer Academic Publishers 323 pp Liou J G and Ernst W G Editors 2000 UltraHigh Pressure Metamorphism and Geodynamics in Collision Type Orogenic Belts Geological Society of America International Book Series volume 4 293 pp Hacker B R McClelland W C and Liou J G Editors 2006 Ultrahigh Pressure Metamorphism Deep Continental Subduction Geological Society of America Special Paper 403 206 pp Retrieved from https en wikipedia org w index php title Ultra high pressure metamorphism amp oldid 1139728457, wikipedia, wiki, book, books, library,

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