Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides
Abstract In the North‐East Greenland Caledonides, P–T conditions and textures are consistent with partial melting of ultrahigh‐pressure ( UHP ) eclogite during exhumation. The eclogite contains a peak assemblage of garnet, omphacite, kyanite, coesite, rutile, and clinozoisite; in addition, phengite...
Published in: | Journal of Metamorphic Geology |
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Online Access: | http://dx.doi.org/10.1111/jmg.12447 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjmg.12447 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12447 |
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crwiley:10.1111/jmg.12447 2024-09-15T18:04:17+00:00 Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides Cao, Wentao Gilotti, Jane A. Massonne, Hans‐Joachim Ferrando, Simona Foster, Charles T. National Science Foundation Division of Earth Sciences 2018 http://dx.doi.org/10.1111/jmg.12447 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjmg.12447 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12447 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#am http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Metamorphic Geology volume 37, issue 1, page 15-39 ISSN 0263-4929 1525-1314 journal-article 2018 crwiley https://doi.org/10.1111/jmg.12447 2024-07-11T04:38:21Z Abstract In the North‐East Greenland Caledonides, P–T conditions and textures are consistent with partial melting of ultrahigh‐pressure ( UHP ) eclogite during exhumation. The eclogite contains a peak assemblage of garnet, omphacite, kyanite, coesite, rutile, and clinozoisite; in addition, phengite is inferred to have been present at peak conditions. An isochemical phase equilibrium diagram, along with garnet isopleths, constrains peak P–T conditions to be subsolidus at 3.4 GP a and 940°C. Zr‐in‐rutile thermometry on inclusions in garnet yields values of ~820°C at 3.4 GP a. In the eclogite, plagioclase may exhibit cuspate textures against surrounding omphacite and has low dihedral angles in plagioclase–clinopyroxene–garnet aggregates, features that are consistent with former melt–solid–solid boundaries and crystallized melt pockets. Graphic intergrowths of plagioclase and amphibole are present in the matrix. Small euhedral neoblasts of garnet against plagioclase are interpreted as formed from a peritectic reaction during partial melting. Polymineralic inclusions of albite+K‐feldspar and clinopyroxene+quartz±kyanite±plagioclase in large anhedral garnet display plagioclase cusps pointing into the host, which are interpreted as crystallized melt pockets. These textures, along with the mineral composition, suggest partial melting of the eclogite by reactions involving phengite and, to a large extent, an epidote‐group mineral. Calculated and experimentally determined phase relations from the literature reveal that partial melting occurred on the exhumation path, at pressures below the coesite to quartz transition. A calculated P–T phase diagram for a former melt‐bearing domain shows that the formation of the peritectic garnet rim occurred at 1.4 GP a and 900°C, with an assemblage of clinopyroxene, amphibole, and plagioclase equilibrated at 1.3 GP a and 720°C. Isochemical phase equilibrium modelling of a symplectite of clinopyroxene, plagioclase, and amphibole after omphacite, combined with the mineral composition, ... Article in Journal/Newspaper East Greenland Greenland Wiley Online Library Journal of Metamorphic Geology 37 1 15 39 |
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Wiley Online Library |
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English |
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Abstract In the North‐East Greenland Caledonides, P–T conditions and textures are consistent with partial melting of ultrahigh‐pressure ( UHP ) eclogite during exhumation. The eclogite contains a peak assemblage of garnet, omphacite, kyanite, coesite, rutile, and clinozoisite; in addition, phengite is inferred to have been present at peak conditions. An isochemical phase equilibrium diagram, along with garnet isopleths, constrains peak P–T conditions to be subsolidus at 3.4 GP a and 940°C. Zr‐in‐rutile thermometry on inclusions in garnet yields values of ~820°C at 3.4 GP a. In the eclogite, plagioclase may exhibit cuspate textures against surrounding omphacite and has low dihedral angles in plagioclase–clinopyroxene–garnet aggregates, features that are consistent with former melt–solid–solid boundaries and crystallized melt pockets. Graphic intergrowths of plagioclase and amphibole are present in the matrix. Small euhedral neoblasts of garnet against plagioclase are interpreted as formed from a peritectic reaction during partial melting. Polymineralic inclusions of albite+K‐feldspar and clinopyroxene+quartz±kyanite±plagioclase in large anhedral garnet display plagioclase cusps pointing into the host, which are interpreted as crystallized melt pockets. These textures, along with the mineral composition, suggest partial melting of the eclogite by reactions involving phengite and, to a large extent, an epidote‐group mineral. Calculated and experimentally determined phase relations from the literature reveal that partial melting occurred on the exhumation path, at pressures below the coesite to quartz transition. A calculated P–T phase diagram for a former melt‐bearing domain shows that the formation of the peritectic garnet rim occurred at 1.4 GP a and 900°C, with an assemblage of clinopyroxene, amphibole, and plagioclase equilibrated at 1.3 GP a and 720°C. Isochemical phase equilibrium modelling of a symplectite of clinopyroxene, plagioclase, and amphibole after omphacite, combined with the mineral composition, ... |
author2 |
National Science Foundation Division of Earth Sciences |
format |
Article in Journal/Newspaper |
author |
Cao, Wentao Gilotti, Jane A. Massonne, Hans‐Joachim Ferrando, Simona Foster, Charles T. |
spellingShingle |
Cao, Wentao Gilotti, Jane A. Massonne, Hans‐Joachim Ferrando, Simona Foster, Charles T. Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
author_facet |
Cao, Wentao Gilotti, Jane A. Massonne, Hans‐Joachim Ferrando, Simona Foster, Charles T. |
author_sort |
Cao, Wentao |
title |
Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
title_short |
Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
title_full |
Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
title_fullStr |
Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
title_full_unstemmed |
Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides |
title_sort |
partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: an example from the north‐east greenland caledonides |
publisher |
Wiley |
publishDate |
2018 |
url |
http://dx.doi.org/10.1111/jmg.12447 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjmg.12447 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jmg.12447 https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/jmg.12447 |
genre |
East Greenland Greenland |
genre_facet |
East Greenland Greenland |
op_source |
Journal of Metamorphic Geology volume 37, issue 1, page 15-39 ISSN 0263-4929 1525-1314 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#am http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/jmg.12447 |
container_title |
Journal of Metamorphic Geology |
container_volume |
37 |
container_issue |
1 |
container_start_page |
15 |
op_container_end_page |
39 |
_version_ |
1810441787369586688 |