Garnet–Clinopyroxene Double‐Layered Coronae in a Metagabbronorite From the High‐Grade Metamorphic Gföhl Unit, Moldanubian Zone.
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| Title: | Garnet–Clinopyroxene Double‐Layered Coronae in a Metagabbronorite From the High‐Grade Metamorphic Gföhl Unit, Moldanubian Zone. |
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| Authors: | Asenbaum, Rene1 (AUTHOR), Nemeškalová, Tereza2 (AUTHOR), Racek, Martin3 (AUTHOR), Janoušek, Vojtěch2,3 (AUTHOR), Portenkirchner, Julian1 (AUTHOR), Abart, Rainer1 (AUTHOR) rainer.abart@univie.ac.at |
| Source: | Journal of Metamorphic Geology. May2026, Vol. 44 Issue 4, p311-336. 26p. |
| Subject Terms: | *Garnet, *Pyroxene, *Metamorphic rocks, *Metamorphism (Geology) |
| Geographic Terms: | Bohemian Massif (Czech Republic) |
| Abstract: | This study investigates garnet–clinopyroxene double‐layered coronae in a metagabbronorite from the high‐grade metamorphic Gföhl Unit (Bohemian Massif). The coronae formed at the interfaces between relic magmatic orthopyroxene, still preserved in the cores of the coronae, and the plagioclase‐rich rock matrix. They comprise an inner clinopyroxene layer and an outer garnet layer, both of which are polycrystalline. The coronae record a polyphase metamorphic evolution. The first metamorphic stage occurred under high‐pressure–high‐temperature (H P–H T) conditions and produced the garnet–clinopyroxene coronae. The garnet layer exhibits a pronounced overall compositional zoning, with inward‐decreasing grossular and outward‐decreasing pyrope contents, reflecting chemical potential gradients that drove the necessary chemical mass transfer during corona growth. Subsequent decompression led to a granulite‐facies overprint, which is manifest from discontinuous layers of secondary orthopyroxene and plagioclase along the interface between the stage‐I garnet and clinopyroxene layers. In addition, a secondary compositional zoning developed on the scale of individual garnet grains, which is characterised by a rimward decrease in the grossular content and a concomitant increase in the pyrope and almandine contents. The resulting complex compositional zoning of garnet allows distinguishing between the features generated during the early H P–H T evolution and those associated with decompression. Thermodynamic modelling yields pressure–temperature conditions indicating formation of the primary garnet–clinopyroxene double‐layered coronae at conditions corresponding to a geothermal gradient of approximately 15°C/km, followed by isothermal decompression and, finally, by rapid cooling. The inferred conditions for the H P–H T stage likely reflect a transitional geodynamic setting involving deceleration of a subducting slab and associated thermal relaxation. [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 192785990 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Garnet–Clinopyroxene Double‐Layered Coronae in a Metagabbronorite From the High‐Grade Metamorphic Gföhl Unit, Moldanubian Zone. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Asenbaum%2C+Rene%22">Asenbaum, Rene</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Nemeškalová%2C+Tereza%22">Nemeškalová, Tereza</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Racek%2C+Martin%22">Racek, Martin</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Janoušek%2C+Vojtěch%22">Janoušek, Vojtěch</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Portenkirchner%2C+Julian%22">Portenkirchner, Julian</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Abart%2C+Rainer%22">Abart, Rainer</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> rainer.abart@univie.ac.at</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Metamorphic+Geology%22">Journal of Metamorphic Geology</searchLink>. May2026, Vol. 44 Issue 4, p311-336. 26p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Garnet%22">Garnet</searchLink><br />*<searchLink fieldCode="DE" term="%22Pyroxene%22">Pyroxene</searchLink><br />*<searchLink fieldCode="DE" term="%22Metamorphic+rocks%22">Metamorphic rocks</searchLink><br />*<searchLink fieldCode="DE" term="%22Metamorphism+%28Geology%29%22">Metamorphism (Geology)</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Bohemian+Massif+%28Czech+Republic%29%22">Bohemian Massif (Czech Republic)</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: This study investigates garnet–clinopyroxene double‐layered coronae in a metagabbronorite from the high‐grade metamorphic Gföhl Unit (Bohemian Massif). The coronae formed at the interfaces between relic magmatic orthopyroxene, still preserved in the cores of the coronae, and the plagioclase‐rich rock matrix. They comprise an inner clinopyroxene layer and an outer garnet layer, both of which are polycrystalline. The coronae record a polyphase metamorphic evolution. The first metamorphic stage occurred under high‐pressure–high‐temperature (H P–H T) conditions and produced the garnet–clinopyroxene coronae. The garnet layer exhibits a pronounced overall compositional zoning, with inward‐decreasing grossular and outward‐decreasing pyrope contents, reflecting chemical potential gradients that drove the necessary chemical mass transfer during corona growth. Subsequent decompression led to a granulite‐facies overprint, which is manifest from discontinuous layers of secondary orthopyroxene and plagioclase along the interface between the stage‐I garnet and clinopyroxene layers. In addition, a secondary compositional zoning developed on the scale of individual garnet grains, which is characterised by a rimward decrease in the grossular content and a concomitant increase in the pyrope and almandine contents. The resulting complex compositional zoning of garnet allows distinguishing between the features generated during the early H P–H T evolution and those associated with decompression. Thermodynamic modelling yields pressure–temperature conditions indicating formation of the primary garnet–clinopyroxene double‐layered coronae at conditions corresponding to a geothermal gradient of approximately 15°C/km, followed by isothermal decompression and, finally, by rapid cooling. The inferred conditions for the H P–H T stage likely reflect a transitional geodynamic setting involving deceleration of a subducting slab and associated thermal relaxation. [ABSTRACT FROM AUTHOR] |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1111/jmg.70036 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 26 StartPage: 311 Subjects: – SubjectFull: Garnet Type: general – SubjectFull: Pyroxene Type: general – SubjectFull: Metamorphic rocks Type: general – SubjectFull: Metamorphism (Geology) Type: general – SubjectFull: Bohemian Massif (Czech Republic) Type: general Titles: – TitleFull: Garnet–Clinopyroxene Double‐Layered Coronae in a Metagabbronorite From the High‐Grade Metamorphic Gföhl Unit, Moldanubian Zone. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Asenbaum, Rene – PersonEntity: Name: NameFull: Nemeškalová, Tereza – PersonEntity: Name: NameFull: Racek, Martin – PersonEntity: Name: NameFull: Janoušek, Vojtěch – PersonEntity: Name: NameFull: Portenkirchner, Julian – PersonEntity: Name: NameFull: Abart, Rainer IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2026 Type: published Y: 2026 Identifiers: – Type: issn-print Value: 02634929 Numbering: – Type: volume Value: 44 – Type: issue Value: 4 Titles: – TitleFull: Journal of Metamorphic Geology Type: main |
| ResultId | 1 |
