Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism.
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| Title: | Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism. |
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| Authors: | Condamine, Pierre1,2,3 p.condamine@opgc.univ-bpclermont.fr, Médard, Etienne1,2,3 |
| Source: | Earth & Planetary Science Letters. Jul2014, Vol. 397, p80-92. 13p. |
| Subjects: | Phlogopite, Magmatism, Fluid dynamics, Extraction (Chemistry), Orthopyroxene, Viscosity |
| Abstract: | We have experimentally investigated the fluid-absent melting of a phlogopite peridotite at 1.0 GPa (1000–1300 °C) to understand the source of K2O- and SiO2-rich magmas that occur in continental, post-collisional and island arc settings. Using a new extraction technique specially developed for hydrous conditions combined with iterative sandwich experiments, we have determined the composition of low- to high-degree melts ( to 24.2 wt.%) of metasomatized lherzolite and harzburgite sources. Due to small amounts of adsorbed water in the starting material, amphibole crystallized at the lowest investigated temperatures. Amphibole breaks down at 1050–1075 °C, while phlogopite-breakdown occurs at 1150–1200 °C. This last temperature is higher than the previously determined in a mantle assemblage, due to the presence of stabilizing F and Ti. Phlogopite–lherzolite melts incongruently according to the continuous reaction: 0.49 phlogopite + 0.56 orthopyroxene + 0.47 clinopyroxene + 0.05 spinel = 0.58 olivine + 1.00 melt. In the phlogopite–harzburgite, the reaction is: 0.70 phlogopite + 1.24 orthopyroxene + 0.05 spinel = 0.99 olivine + 1.00 melt. The K2O content of water-undersaturated melts in equilibrium with residual phlogopite is buffered, depending on the source fertility: from in lherzolite to in harzburgite. Primary melts are silica-saturated and evolve from trachyte to basaltic andesite (63.5–52.1 wt.% SiO2) with increasing temperature. Calculations indicate that such silica-rich melts can readily be extracted from their mantle source, due to their low viscosity. Our results confirm that potassic, silica-rich magmas described worldwide in post-collisional settings are generated by melting of a metasomatized phlogopite-bearing mantle in the spinel stability field. [ABSTRACT FROM AUTHOR] |
| Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 96188326 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Condamine%2C+Pierre%22">Condamine, Pierre</searchLink><relatesTo>1,2,3</relatesTo><i> p.condamine@opgc.univ-bpclermont.fr</i><br /><searchLink fieldCode="AR" term="%22Médard%2C+Etienne%22">Médard, Etienne</searchLink><relatesTo>1,2,3</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Earth+%26+Planetary+Science+Letters%22">Earth & Planetary Science Letters</searchLink>. Jul2014, Vol. 397, p80-92. 13p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Phlogopite%22">Phlogopite</searchLink><br /><searchLink fieldCode="DE" term="%22Magmatism%22">Magmatism</searchLink><br /><searchLink fieldCode="DE" term="%22Fluid+dynamics%22">Fluid dynamics</searchLink><br /><searchLink fieldCode="DE" term="%22Extraction+%28Chemistry%29%22">Extraction (Chemistry)</searchLink><br /><searchLink fieldCode="DE" term="%22Orthopyroxene%22">Orthopyroxene</searchLink><br /><searchLink fieldCode="DE" term="%22Viscosity%22">Viscosity</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We have experimentally investigated the fluid-absent melting of a phlogopite peridotite at 1.0 GPa (1000–1300 °C) to understand the source of K2O- and SiO2-rich magmas that occur in continental, post-collisional and island arc settings. Using a new extraction technique specially developed for hydrous conditions combined with iterative sandwich experiments, we have determined the composition of low- to high-degree melts ( to 24.2 wt.%) of metasomatized lherzolite and harzburgite sources. Due to small amounts of adsorbed water in the starting material, amphibole crystallized at the lowest investigated temperatures. Amphibole breaks down at 1050–1075 °C, while phlogopite-breakdown occurs at 1150–1200 °C. This last temperature is higher than the previously determined in a mantle assemblage, due to the presence of stabilizing F and Ti. Phlogopite–lherzolite melts incongruently according to the continuous reaction: 0.49 phlogopite + 0.56 orthopyroxene + 0.47 clinopyroxene + 0.05 spinel = 0.58 olivine + 1.00 melt. In the phlogopite–harzburgite, the reaction is: 0.70 phlogopite + 1.24 orthopyroxene + 0.05 spinel = 0.99 olivine + 1.00 melt. The K2O content of water-undersaturated melts in equilibrium with residual phlogopite is buffered, depending on the source fertility: from in lherzolite to in harzburgite. Primary melts are silica-saturated and evolve from trachyte to basaltic andesite (63.5–52.1 wt.% SiO2) with increasing temperature. Calculations indicate that such silica-rich melts can readily be extracted from their mantle source, due to their low viscosity. Our results confirm that potassic, silica-rich magmas described worldwide in post-collisional settings are generated by melting of a metasomatized phlogopite-bearing mantle in the spinel stability field. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.epsl.2014.04.027 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 13 StartPage: 80 Subjects: – SubjectFull: Phlogopite Type: general – SubjectFull: Magmatism Type: general – SubjectFull: Fluid dynamics Type: general – SubjectFull: Extraction (Chemistry) Type: general – SubjectFull: Orthopyroxene Type: general – SubjectFull: Viscosity Type: general Titles: – TitleFull: Experimental melting of phlogopite-bearing mantle at 1 GPa: Implications for potassic magmatism. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Condamine, Pierre – PersonEntity: Name: NameFull: Médard, Etienne IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 07 Text: Jul2014 Type: published Y: 2014 Identifiers: – Type: issn-print Value: 0012821X Numbering: – Type: volume Value: 397 Titles: – TitleFull: Earth & Planetary Science Letters Type: main |
| ResultId | 1 |
