Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia.
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| Title: | Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia. |
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| Authors: | Nosova, A. A.1 (AUTHOR) nosova@igem.ru, Lebedeva, N. M.1 (AUTHOR), Vozniak, A. A.1 (AUTHOR), Sazonova, L. V.1,2 (AUTHOR), Kondrashov, I. A.1 (AUTHOR), Larionova, Y. O.1 (AUTHOR), Kovalchuk, E. V.1 (AUTHOR) |
| Source: | Petrology. Jun2024, Vol. 32 Issue 3, p307-336. 30p. |
| Subject Terms: | *Sills (Geology), *Immiscibility, *Olivine, *Petrogenesis, *Crystallization, *Magmas, *Iron, *Platinum group |
| Geographic Terms: | Scandinavia |
| Abstract: | This paper presents the results of petrographical, mineralogical, geochemical, and isotope-geochemical studies of granophyres and host ferrogabbros, quartz ferromonzogabbros, quartz monzodiorites, and quartz monzonites in the Mesoproterozoic Valaam sill in the Ladoga Graben on the Karelian Craton. The sill is poorly layered: the ferrogabbros compose the lower part of the sill, the middle part consists of quartz gabbro-monzonites and quartz monzonites, while graphic leucogranites (granophyres) form a dense network of veins mainly in the upper part of the sill. Geochemical features of ferrogabbro, iron-rich composition of olivine and pyroxene, and low Ca composition of plagioclase indicate the evolution along the Fenner trend. The granophyres have petro- and geochemical characteristics of anorogenic alkaline granites, with negative Eu/Eu* = 0.15–0.49 and REE distribution patterns similar to those of granophyres of layered intrusions. All rocks of the sill have close Sr isotopic composition (87Sr/86Sr)T = 0.7043–0.7066, and εNd values ranging from −9.6 to −11.2. Model calculations show that fractional crystallization can lead the initial ferrogabbro melt into the immiscibility field. Ilmenite–magnetite–silicate microstructures have been identified in the ferrogabbro and ferromontzogabbro from the sill; similar microstructures in layered intrusions are considered as evidence for the immiscibility of Fe-rich and Si-rich liquids (Holness et al., 2011; Dong et al., 2013). The segregation of the high-silica melt may have occurred in an intermediate crustal chamber at around 350 MPa and 960oC; magma was supplied as crystalline mush at the sill emplacement level at around 70 MPa and acidic melt migrated through it. This melt underwent fractional crystallization and interacted with host minerals. At the level of sill emplacement, it crystallized under supercooling into granophyre aggregates. The example of the Valaam sill shows that when the Fenner fractionation reaches the final composition–-ferrogabbro, its further evolution with a conjugate decrease in SiO2 and Fe contents can be related to the incomplete separation and mixing of Fe-rich melts and immiscibly split felsic melt. Such a mechanism can be implemented for the formation of the mafic part of AMCG-type massifs. [ABSTRACT FROM AUTHOR] |
| Database: | Energy & Power Source |
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| Header | DbId: enr DbLabel: Energy & Power Source An: 177540521 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Nosova%2C+A%2E+A%2E%22">Nosova, A. A.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> nosova@igem.ru</i><br /><searchLink fieldCode="AR" term="%22Lebedeva%2C+N%2E+M%2E%22">Lebedeva, N. M.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Vozniak%2C+A%2E+A%2E%22">Vozniak, A. A.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Sazonova%2C+L%2E+V%2E%22">Sazonova, L. V.</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kondrashov%2C+I%2E+A%2E%22">Kondrashov, I. A.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Larionova%2C+Y%2E+O%2E%22">Larionova, Y. O.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kovalchuk%2C+E%2E+V%2E%22">Kovalchuk, E. V.</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Petrology%22">Petrology</searchLink>. Jun2024, Vol. 32 Issue 3, p307-336. 30p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Sills+%28Geology%29%22">Sills (Geology)</searchLink><br />*<searchLink fieldCode="DE" term="%22Immiscibility%22">Immiscibility</searchLink><br />*<searchLink fieldCode="DE" term="%22Olivine%22">Olivine</searchLink><br />*<searchLink fieldCode="DE" term="%22Petrogenesis%22">Petrogenesis</searchLink><br />*<searchLink fieldCode="DE" term="%22Crystallization%22">Crystallization</searchLink><br />*<searchLink fieldCode="DE" term="%22Magmas%22">Magmas</searchLink><br />*<searchLink fieldCode="DE" term="%22Iron%22">Iron</searchLink><br />*<searchLink fieldCode="DE" term="%22Platinum+group%22">Platinum group</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Scandinavia%22">Scandinavia</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: This paper presents the results of petrographical, mineralogical, geochemical, and isotope-geochemical studies of granophyres and host ferrogabbros, quartz ferromonzogabbros, quartz monzodiorites, and quartz monzonites in the Mesoproterozoic Valaam sill in the Ladoga Graben on the Karelian Craton. The sill is poorly layered: the ferrogabbros compose the lower part of the sill, the middle part consists of quartz gabbro-monzonites and quartz monzonites, while graphic leucogranites (granophyres) form a dense network of veins mainly in the upper part of the sill. Geochemical features of ferrogabbro, iron-rich composition of olivine and pyroxene, and low Ca composition of plagioclase indicate the evolution along the Fenner trend. The granophyres have petro- and geochemical characteristics of anorogenic alkaline granites, with negative Eu/Eu* = 0.15–0.49 and REE distribution patterns similar to those of granophyres of layered intrusions. All rocks of the sill have close Sr isotopic composition (87Sr/86Sr)T = 0.7043–0.7066, and εNd values ranging from −9.6 to −11.2. Model calculations show that fractional crystallization can lead the initial ferrogabbro melt into the immiscibility field. Ilmenite–magnetite–silicate microstructures have been identified in the ferrogabbro and ferromontzogabbro from the sill; similar microstructures in layered intrusions are considered as evidence for the immiscibility of Fe-rich and Si-rich liquids (Holness et al., 2011; Dong et al., 2013). The segregation of the high-silica melt may have occurred in an intermediate crustal chamber at around 350 MPa and 960oC; magma was supplied as crystalline mush at the sill emplacement level at around 70 MPa and acidic melt migrated through it. This melt underwent fractional crystallization and interacted with host minerals. At the level of sill emplacement, it crystallized under supercooling into granophyre aggregates. The example of the Valaam sill shows that when the Fenner fractionation reaches the final composition–-ferrogabbro, its further evolution with a conjugate decrease in SiO2 and Fe contents can be related to the incomplete separation and mixing of Fe-rich melts and immiscibly split felsic melt. Such a mechanism can be implemented for the formation of the mafic part of AMCG-type massifs. [ABSTRACT FROM AUTHOR] |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=enr&AN=177540521 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1134/S086959112470005X Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 30 StartPage: 307 Subjects: – SubjectFull: Sills (Geology) Type: general – SubjectFull: Immiscibility Type: general – SubjectFull: Olivine Type: general – SubjectFull: Petrogenesis Type: general – SubjectFull: Crystallization Type: general – SubjectFull: Magmas Type: general – SubjectFull: Iron Type: general – SubjectFull: Platinum group Type: general – SubjectFull: Scandinavia Type: general Titles: – TitleFull: Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Nosova, A. A. – PersonEntity: Name: NameFull: Lebedeva, N. M. – PersonEntity: Name: NameFull: Vozniak, A. A. – PersonEntity: Name: NameFull: Sazonova, L. V. – PersonEntity: Name: NameFull: Kondrashov, I. A. – PersonEntity: Name: NameFull: Larionova, Y. O. – PersonEntity: Name: NameFull: Kovalchuk, E. V. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 06 Text: Jun2024 Type: published Y: 2024 Identifiers: – Type: issn-print Value: 08695911 Numbering: – Type: volume Value: 32 – Type: issue Value: 3 Titles: – TitleFull: Petrology Type: main |
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