Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica)
Amphiboles are the most widespread hydrous metasomatic phases in spinel-bearing mantle peridotites from Harrow Peaks (HP), Northern Victoria Land (Antarctica). They occur both in veinlets and disseminated in the peridotite matrix (preferentially associated with clinopyroxene and spinel grains). Four...
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ftunivpisairis:oai:arpi.unipi.it:11568/785182 2024-02-11T09:56:00+01:00 Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) Gentili, S Bonadiman, C. Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. BIAGIONI, CRISTIAN Gentili, S Bonadiman, C. Biagioni, Cristian Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. 2015 ELETTRONICO http://hdl.handle.net/11568/785182 https://doi.org/10.1007/s00710-015-0404-4 http://www.link.springer.de/link/service/journals/00710/about.htm eng eng info:eu-repo/semantics/altIdentifier/wos/WOS:000365098200008 volume:109 issue:6 firstpage:741 lastpage:759 numberofpages:19 journal:MINERALOGY AND PETROLOGY http://hdl.handle.net/11568/785182 doi:10.1007/s00710-015-0404-4 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84947490811 http://www.link.springer.de/link/service/journals/00710/about.htm Geochemistry and Petrology Geophysics info:eu-repo/semantics/article 2015 ftunivpisairis https://doi.org/10.1007/s00710-015-0404-4 2024-01-17T17:56:19Z Amphiboles are the most widespread hydrous metasomatic phases in spinel-bearing mantle peridotites from Harrow Peaks (HP), Northern Victoria Land (Antarctica). They occur both in veinlets and disseminated in the peridotite matrix (preferentially associated with clinopyroxene and spinel grains). Four amphibole crystals were investigated by single-crystal X-ray diffraction (SC-XRD), electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS) and micro-Mössbauer spectroscopy; these crystal-chemical data allow to constrain upper mantle conditions during growth of these amphiboles and the role of volatile circulation during metasomatic processes in the Antarctic region. The HP amphiboles have low Mg# values (69.3–84.1), high TiO2 (2.74–5.30 wt%) and FeOtot contents (3.40 to 6.90 wt%). The Fe3+/Fetot ratios are significantly high (0.53–0.66). The W-site is mainly occupied by O2- (0.984–1.187 apfu) plus OH (H2O: 0.70–1.01 wt%) and minor F (0.04–0.24 wt%) and Cl (0.03–0.08 wt%). Consequently, HP amphiboles are actually characterized by a significant oxo component. The aH2O values were calculated at 1.5 GPa by dehydration equilibrium equations written as H2O-buffering equilibria among end-member components of amphibole and coexisting peridotite phases. Three out of four HP amphibole-bearing peridotites have values of aH2O ranging from 0.122 to 0.335; whereas one sample has aH2O remarkably higher (0.782) approaching an ideal H2O basalt solubility. The HP fO2 values, determined by the olivine-spinel-orthopyroxene oxygeobarometer (ΔQFM = −1.77 : +0.01), are remarkably different from those calculated on the basis of the amphibole dehydration equilibrium and the application of the dissociation reaction (ΔQFM = −2.60 : +6.8). The high aH2O and the extremely high fO2 values, determined by the oxy-amphibole equilibrium with respect to the redox conditions recorded by the co-existing anhydrous minerals (close to QFM buffer), revealed that: i) the amphibole-forming reaction is a relatively recent process with the ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Victoria Land ARPI - Archivio della Ricerca dell'Università di Pisa Antarctic The Antarctic Victoria Land Harrow Peaks ENVELOPE(164.750,164.750,-74.067,-74.067) Mineralogy and Petrology 109 6 741 759 |
institution |
Open Polar |
collection |
ARPI - Archivio della Ricerca dell'Università di Pisa |
op_collection_id |
ftunivpisairis |
language |
English |
topic |
Geochemistry and Petrology Geophysics |
spellingShingle |
Geochemistry and Petrology Geophysics Gentili, S Bonadiman, C. Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. BIAGIONI, CRISTIAN Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
topic_facet |
Geochemistry and Petrology Geophysics |
description |
Amphiboles are the most widespread hydrous metasomatic phases in spinel-bearing mantle peridotites from Harrow Peaks (HP), Northern Victoria Land (Antarctica). They occur both in veinlets and disseminated in the peridotite matrix (preferentially associated with clinopyroxene and spinel grains). Four amphibole crystals were investigated by single-crystal X-ray diffraction (SC-XRD), electron microprobe analysis (EMPA), secondary ion mass spectrometry (SIMS) and micro-Mössbauer spectroscopy; these crystal-chemical data allow to constrain upper mantle conditions during growth of these amphiboles and the role of volatile circulation during metasomatic processes in the Antarctic region. The HP amphiboles have low Mg# values (69.3–84.1), high TiO2 (2.74–5.30 wt%) and FeOtot contents (3.40 to 6.90 wt%). The Fe3+/Fetot ratios are significantly high (0.53–0.66). The W-site is mainly occupied by O2- (0.984–1.187 apfu) plus OH (H2O: 0.70–1.01 wt%) and minor F (0.04–0.24 wt%) and Cl (0.03–0.08 wt%). Consequently, HP amphiboles are actually characterized by a significant oxo component. The aH2O values were calculated at 1.5 GPa by dehydration equilibrium equations written as H2O-buffering equilibria among end-member components of amphibole and coexisting peridotite phases. Three out of four HP amphibole-bearing peridotites have values of aH2O ranging from 0.122 to 0.335; whereas one sample has aH2O remarkably higher (0.782) approaching an ideal H2O basalt solubility. The HP fO2 values, determined by the olivine-spinel-orthopyroxene oxygeobarometer (ΔQFM = −1.77 : +0.01), are remarkably different from those calculated on the basis of the amphibole dehydration equilibrium and the application of the dissociation reaction (ΔQFM = −2.60 : +6.8). The high aH2O and the extremely high fO2 values, determined by the oxy-amphibole equilibrium with respect to the redox conditions recorded by the co-existing anhydrous minerals (close to QFM buffer), revealed that: i) the amphibole-forming reaction is a relatively recent process with the ... |
author2 |
Gentili, S Bonadiman, C. Biagioni, Cristian Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. |
format |
Article in Journal/Newspaper |
author |
Gentili, S Bonadiman, C. Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. BIAGIONI, CRISTIAN |
author_facet |
Gentili, S Bonadiman, C. Comodi, P. Coltorti, M. Zucchini, A. Ottolini, L. BIAGIONI, CRISTIAN |
author_sort |
Gentili, S |
title |
Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
title_short |
Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
title_full |
Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
title_fullStr |
Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
title_full_unstemmed |
Oxo-amphiboles in mantle xenoliths: evidence for H2O-rich melt interacting with the lithospheric mantle of Harrow Peaks (Northern Victoria Land, Antarctica) |
title_sort |
oxo-amphiboles in mantle xenoliths: evidence for h2o-rich melt interacting with the lithospheric mantle of harrow peaks (northern victoria land, antarctica) |
publishDate |
2015 |
url |
http://hdl.handle.net/11568/785182 https://doi.org/10.1007/s00710-015-0404-4 http://www.link.springer.de/link/service/journals/00710/about.htm |
long_lat |
ENVELOPE(164.750,164.750,-74.067,-74.067) |
geographic |
Antarctic The Antarctic Victoria Land Harrow Peaks |
geographic_facet |
Antarctic The Antarctic Victoria Land Harrow Peaks |
genre |
Antarc* Antarctic Antarctica Victoria Land |
genre_facet |
Antarc* Antarctic Antarctica Victoria Land |
op_relation |
info:eu-repo/semantics/altIdentifier/wos/WOS:000365098200008 volume:109 issue:6 firstpage:741 lastpage:759 numberofpages:19 journal:MINERALOGY AND PETROLOGY http://hdl.handle.net/11568/785182 doi:10.1007/s00710-015-0404-4 info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-84947490811 http://www.link.springer.de/link/service/journals/00710/about.htm |
op_doi |
https://doi.org/10.1007/s00710-015-0404-4 |
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Mineralogy and Petrology |
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109 |
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6 |
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741 |
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