Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica
Abstract Precise constraints on the compositions of melts generated by anatexis under ultrahigh temperature (UHT) conditions are critical for understanding processes of partial melting and differentiation of the Earth’s crust. Here we reveal geochemical and physical signatures of anatectic melts pre...
Published in: | Journal of Petrology |
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Language: | English |
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Oxford University Press (OUP)
2023
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Online Access: | http://dx.doi.org/10.1093/petrology/egad051 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad051/50791246/egad051.pdf https://academic.oup.com/petrology/article-pdf/64/7/egad051/51713537/egad051.pdf |
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croxfordunivpr:10.1093/petrology/egad051 2024-10-13T14:02:55+00:00 Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica Liu, Zhao Carvalho, Bruna B Li, Wancai Tong, Laixi Bartoli, Omar Chen, Longyao Yan, Qinghe Wu, Haobo 2023 http://dx.doi.org/10.1093/petrology/egad051 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad051/50791246/egad051.pdf https://academic.oup.com/petrology/article-pdf/64/7/egad051/51713537/egad051.pdf en eng Oxford University Press (OUP) https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model Journal of Petrology volume 64, issue 7 ISSN 0022-3530 1460-2415 journal-article 2023 croxfordunivpr https://doi.org/10.1093/petrology/egad051 2024-09-17T04:27:04Z Abstract Precise constraints on the compositions of melts generated by anatexis under ultrahigh temperature (UHT) conditions are critical for understanding processes of partial melting and differentiation of the Earth’s crust. Here we reveal geochemical and physical signatures of anatectic melts preserved as nanogranitoids (i.e. crystalized melt inclusions) within sapphirine-bearing UHT metapelitic granulites from the Mather Peninsula, East Antarctica. Their coexistence with high−Al orthopyroxene as inclusions in garnets strongly suggests that the investigated melts were at least partially UHT in origin. The nanogranitoids are enriched in SiO2 (69.9–75.6 wt.%), strongly peraluminous (ASI values = 1.2–1.6) and potassic to ultrapotassic (Na2O + K2O = 7.1–9.5 wt.%, K/Na = 2.2–9.3). When compared to the granulitic restite, the melts are enriched in Li, Cs, Rb, Ta, Sm, Nd, Zr, U and Pb, and depleted in Ce, Th, Ba, Sr and Nb. Their geochemical characteristics are consistent with biotite−dehydration melting in the absence of plagioclase. Our calculation results indicate that these hot crustal melts have low densities of 2.47 ± 0.07 g/cm3, low viscosities of 104.9 ± 1.2 Pa·s and high heat production values of ∼2.8 μW/m3. Therefore, such melts are mobile and susceptible to be extracted from the source, and consequently their flow and removal from the deep crust may greatly affect the chemical and thermal structure of the continental crust. Secondary C − O − H fluid inclusions within garnet and orthopyroxene have also been detected. These inclusions contain magnesite, pyrophyllite, corundum, with or without residual CO2. The minerals within the fluid inclusions are interpreted as stepdaughter minerals, which were produced by the reaction of the fluid with its host. The metamorphic timing of the investigated rocks is still a matter of debate. Zircon U–Pb dating results obtained in this study suggest that the metapelitic granulites may have undergone two separated thermal events at ∼1000 and ∼530 Ma, respectively. The ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Oxford University Press East Antarctica Mather Peninsula ENVELOPE(77.922,77.922,-68.847,-68.847) Journal of Petrology |
institution |
Open Polar |
collection |
Oxford University Press |
op_collection_id |
croxfordunivpr |
language |
English |
description |
Abstract Precise constraints on the compositions of melts generated by anatexis under ultrahigh temperature (UHT) conditions are critical for understanding processes of partial melting and differentiation of the Earth’s crust. Here we reveal geochemical and physical signatures of anatectic melts preserved as nanogranitoids (i.e. crystalized melt inclusions) within sapphirine-bearing UHT metapelitic granulites from the Mather Peninsula, East Antarctica. Their coexistence with high−Al orthopyroxene as inclusions in garnets strongly suggests that the investigated melts were at least partially UHT in origin. The nanogranitoids are enriched in SiO2 (69.9–75.6 wt.%), strongly peraluminous (ASI values = 1.2–1.6) and potassic to ultrapotassic (Na2O + K2O = 7.1–9.5 wt.%, K/Na = 2.2–9.3). When compared to the granulitic restite, the melts are enriched in Li, Cs, Rb, Ta, Sm, Nd, Zr, U and Pb, and depleted in Ce, Th, Ba, Sr and Nb. Their geochemical characteristics are consistent with biotite−dehydration melting in the absence of plagioclase. Our calculation results indicate that these hot crustal melts have low densities of 2.47 ± 0.07 g/cm3, low viscosities of 104.9 ± 1.2 Pa·s and high heat production values of ∼2.8 μW/m3. Therefore, such melts are mobile and susceptible to be extracted from the source, and consequently their flow and removal from the deep crust may greatly affect the chemical and thermal structure of the continental crust. Secondary C − O − H fluid inclusions within garnet and orthopyroxene have also been detected. These inclusions contain magnesite, pyrophyllite, corundum, with or without residual CO2. The minerals within the fluid inclusions are interpreted as stepdaughter minerals, which were produced by the reaction of the fluid with its host. The metamorphic timing of the investigated rocks is still a matter of debate. Zircon U–Pb dating results obtained in this study suggest that the metapelitic granulites may have undergone two separated thermal events at ∼1000 and ∼530 Ma, respectively. The ... |
format |
Article in Journal/Newspaper |
author |
Liu, Zhao Carvalho, Bruna B Li, Wancai Tong, Laixi Bartoli, Omar Chen, Longyao Yan, Qinghe Wu, Haobo |
spellingShingle |
Liu, Zhao Carvalho, Bruna B Li, Wancai Tong, Laixi Bartoli, Omar Chen, Longyao Yan, Qinghe Wu, Haobo Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
author_facet |
Liu, Zhao Carvalho, Bruna B Li, Wancai Tong, Laixi Bartoli, Omar Chen, Longyao Yan, Qinghe Wu, Haobo |
author_sort |
Liu, Zhao |
title |
Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
title_short |
Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
title_full |
Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
title_fullStr |
Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
title_full_unstemmed |
Into the High to Ultrahigh Temperature Melting of Earth’s Crust: Investigation of Melt and Fluid Inclusions within Mg-Rich Metapelitic Granulites from the Mather Peninsula, East Antarctica |
title_sort |
into the high to ultrahigh temperature melting of earth’s crust: investigation of melt and fluid inclusions within mg-rich metapelitic granulites from the mather peninsula, east antarctica |
publisher |
Oxford University Press (OUP) |
publishDate |
2023 |
url |
http://dx.doi.org/10.1093/petrology/egad051 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad051/50791246/egad051.pdf https://academic.oup.com/petrology/article-pdf/64/7/egad051/51713537/egad051.pdf |
long_lat |
ENVELOPE(77.922,77.922,-68.847,-68.847) |
geographic |
East Antarctica Mather Peninsula |
geographic_facet |
East Antarctica Mather Peninsula |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
Journal of Petrology volume 64, issue 7 ISSN 0022-3530 1460-2415 |
op_rights |
https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model |
op_doi |
https://doi.org/10.1093/petrology/egad051 |
container_title |
Journal of Petrology |
_version_ |
1812819370812899328 |