Hydroxyl in eclogitic garnet, orthopyroxene, and oriented inclusion-bearing clinopyroxene, western Norway.
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| Title: | Hydroxyl in eclogitic garnet, orthopyroxene, and oriented inclusion-bearing clinopyroxene, western Norway. |
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| Authors: | Spengler, Dirk1 (AUTHOR) dirk@spengler.eu, Koch-Müller, Monika2 (AUTHOR), Włodek, Adam1 (AUTHOR), Cuthbert, Simon J.1 (AUTHOR), Majka, Jarosław1,3 (AUTHOR) |
| Source: | Solid Earth. 2025, Vol. 16 Issue 3, p233-250. 18p. |
| Subjects: | Orthopyroxene, Extreme value theory, Eclogite, Minerals, Cratons, Garnet |
| Abstract: | A total of 10 western Norwegian eclogites, whose mineral chemistry records metamorphism of up to 850 °C and 5.5 GPa , were investigated for structural hydroxyl content in nominally anhydrous minerals. Garnet shows pronounced absorption in the wavenumber ranges of 3596–3633, 3651–3694, and 3698–3735 cm-1 and minor absorption centred at about 3560 cm-1. Clinopyroxene with aligned inclusions of either quartz, albite, or quartz + pargasite has major absorption at 3450–3471 and 3521–3538 cm-1 and minor absorption centred at 3350 and approximately 3625 cm-1. The latter band is strongest in a sample with minute lamellar inclusions rich in Al, Fe, and Na and was excluded from hydroxyl quantification. Orthopyroxene has large, narrow absorption peaks centred at 3415 and 3515 cm-1 and smaller peaks at 3555, 3595, and 3625 cm-1. Five orthopyroxene-bearing eclogites exhibit relatively homogeneous amounts of structural hydroxyl in garnet (13–32 µgg-1), clinopyroxene (119–174 µgg-1), and orthopyroxene (4–17 µgg-1). The outer 200 µm wide rims of the orthopyroxene grains illustrate a late hydroxyl loss compared to core values of about 30 %, which is not evident in garnet and clinopyroxene. In contrast, the other five orthopyroxene-free eclogites exhibit variable amounts of hydroxyl in garnet (8–306 µgg-1) and clinopyroxene (58–711 µgg-1). Apart from extreme values, the structural hydroxyl content of clinopyroxene in the eclogites studied is lower than in comparable ultra-high-pressure metamorphic samples, e.g. both metasomatised and pristine eclogite xenoliths from the lithospheric mantle underneath several cratons and coesite- and quartz-eclogites from the Erzgebirge and the Kokchetav massifs, by up to several hundreds of micrograms per gram (µgg-1). The low structural hydroxyl contents, the deficiency of molecular water, and the preservation of diffusion-sensitive evidence from the mineral chemistry for metamorphism well beyond the stability field of amphibole suggest that oriented inclusions of quartz + pargasite were formed isochemically during decompression. In addition, structural hydroxyl content in clinopyroxene is inversely correlated with metamorphic pressure estimates obtained from orthopyroxene of the same samples. Therefore, structural hydroxyl in nominally anhydrous eclogite minerals can serve as an indicator of the effectiveness of retrogression. [ABSTRACT FROM AUTHOR] |
| Copyright of Solid Earth is the property of Copernicus Gesellschaft mbH 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.) | |
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| Header | DbId: egs DbLabel: Engineering Source An: 185427121 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Hydroxyl in eclogitic garnet, orthopyroxene, and oriented inclusion-bearing clinopyroxene, western Norway. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Spengler%2C+Dirk%22">Spengler, Dirk</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> dirk@spengler.eu</i><br /><searchLink fieldCode="AR" term="%22Koch-Müller%2C+Monika%22">Koch-Müller, Monika</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Włodek%2C+Adam%22">Włodek, Adam</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Cuthbert%2C+Simon J%2E%22">Cuthbert, Simon J.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Majka%2C+Jarosław%22">Majka, Jarosław</searchLink><relatesTo>1,3</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Solid+Earth%22">Solid Earth</searchLink>. 2025, Vol. 16 Issue 3, p233-250. 18p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Orthopyroxene%22">Orthopyroxene</searchLink><br /><searchLink fieldCode="DE" term="%22Extreme+value+theory%22">Extreme value theory</searchLink><br /><searchLink fieldCode="DE" term="%22Eclogite%22">Eclogite</searchLink><br /><searchLink fieldCode="DE" term="%22Minerals%22">Minerals</searchLink><br /><searchLink fieldCode="DE" term="%22Cratons%22">Cratons</searchLink><br /><searchLink fieldCode="DE" term="%22Garnet%22">Garnet</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: A total of 10 western Norwegian eclogites, whose mineral chemistry records metamorphism of up to 850 °C and 5.5 GPa , were investigated for structural hydroxyl content in nominally anhydrous minerals. Garnet shows pronounced absorption in the wavenumber ranges of 3596–3633, 3651–3694, and 3698–3735 cm-1 and minor absorption centred at about 3560 cm-1. Clinopyroxene with aligned inclusions of either quartz, albite, or quartz + pargasite has major absorption at 3450–3471 and 3521–3538 cm-1 and minor absorption centred at 3350 and approximately 3625 cm-1. The latter band is strongest in a sample with minute lamellar inclusions rich in Al, Fe, and Na and was excluded from hydroxyl quantification. Orthopyroxene has large, narrow absorption peaks centred at 3415 and 3515 cm-1 and smaller peaks at 3555, 3595, and 3625 cm-1. Five orthopyroxene-bearing eclogites exhibit relatively homogeneous amounts of structural hydroxyl in garnet (13–32 µgg-1), clinopyroxene (119–174 µgg-1), and orthopyroxene (4–17 µgg-1). The outer 200 µm wide rims of the orthopyroxene grains illustrate a late hydroxyl loss compared to core values of about 30 %, which is not evident in garnet and clinopyroxene. In contrast, the other five orthopyroxene-free eclogites exhibit variable amounts of hydroxyl in garnet (8–306 µgg-1) and clinopyroxene (58–711 µgg-1). Apart from extreme values, the structural hydroxyl content of clinopyroxene in the eclogites studied is lower than in comparable ultra-high-pressure metamorphic samples, e.g. both metasomatised and pristine eclogite xenoliths from the lithospheric mantle underneath several cratons and coesite- and quartz-eclogites from the Erzgebirge and the Kokchetav massifs, by up to several hundreds of micrograms per gram (µgg-1). The low structural hydroxyl contents, the deficiency of molecular water, and the preservation of diffusion-sensitive evidence from the mineral chemistry for metamorphism well beyond the stability field of amphibole suggest that oriented inclusions of quartz + pargasite were formed isochemically during decompression. In addition, structural hydroxyl content in clinopyroxene is inversely correlated with metamorphic pressure estimates obtained from orthopyroxene of the same samples. Therefore, structural hydroxyl in nominally anhydrous eclogite minerals can serve as an indicator of the effectiveness of retrogression. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Solid Earth is the property of Copernicus Gesellschaft mbH 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: 10.5194/se-16-233-2025 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 18 StartPage: 233 Subjects: – SubjectFull: Orthopyroxene Type: general – SubjectFull: Extreme value theory Type: general – SubjectFull: Eclogite Type: general – SubjectFull: Minerals Type: general – SubjectFull: Cratons Type: general – SubjectFull: Garnet Type: general Titles: – TitleFull: Hydroxyl in eclogitic garnet, orthopyroxene, and oriented inclusion-bearing clinopyroxene, western Norway. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Spengler, Dirk – PersonEntity: Name: NameFull: Koch-Müller, Monika – PersonEntity: Name: NameFull: Włodek, Adam – PersonEntity: Name: NameFull: Cuthbert, Simon J. – PersonEntity: Name: NameFull: Majka, Jarosław IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 03 Text: 2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 18699510 Numbering: – Type: volume Value: 16 – Type: issue Value: 3 Titles: – TitleFull: Solid Earth Type: main |
| ResultId | 1 |
