Zircons were studied from high-pressure / low-temperature metamorphosed meta-igneous lithologies from Syros. These rocks carry several zircon generations related to eachother by dissolution-reprecipitation processes. One generation is pristine zircon that shows growth zoning, relatively elevated contents in trivalent cations, and high Th/U ratios. The other end-member is a skeletal zircon generation with negligible trivalent cation contents and low Th/U ratios (( 0.1). Texturally between these two, there is a range of zircon crystals with complex inclusion populations of Y-HREE-Th phases and fluid inclusions, showing variable progress of replacement-recrystallization. Both end-members yield distinct SHRIMP U-Pb ages. The pristine generation has an age of 80.2 ± 1.6 Ma from a metagabbro, and 76.4 ± 2.1 Ma from a metaplagiogranite dyke. The skeletal, low Th/U zircon generation yields an age of 52.4 ± 0.8 Ma. The Upper Cretaceous zircons are interpreted to date emplacement of the magmatic protoliths in a small segment of oceanic crust. The Eocene age, however, dates a zircon recrystallization event, which possibly coincides with high solubility and mobility of HFSE-elements in a high-pressure aqueous fluid phase. Intergrowth relations between zircon and peak-metamorphic garnet, and excellent agreement of the U-Pb ages with white mica Ar-Ar ages of the same samples support, that Eocene is the true age of high-pressure metamorphism on Syros

Tomaschek, F., Kennedy, A., Villa, I., Lagos, M., Ballhaus, C. (2003). Zircons from Syros, Cyclades, Greece - Recrystallization and mobilization of zircon during high pressure metamorphism. JOURNAL OF PETROLOGY, 44(11), 1977-2002 [10.1093/petrology/egg067].

Zircons from Syros, Cyclades, Greece - Recrystallization and mobilization of zircon during high pressure metamorphism

VILLA, IGOR MARIA;
2003

Abstract

Zircons were studied from high-pressure / low-temperature metamorphosed meta-igneous lithologies from Syros. These rocks carry several zircon generations related to eachother by dissolution-reprecipitation processes. One generation is pristine zircon that shows growth zoning, relatively elevated contents in trivalent cations, and high Th/U ratios. The other end-member is a skeletal zircon generation with negligible trivalent cation contents and low Th/U ratios (( 0.1). Texturally between these two, there is a range of zircon crystals with complex inclusion populations of Y-HREE-Th phases and fluid inclusions, showing variable progress of replacement-recrystallization. Both end-members yield distinct SHRIMP U-Pb ages. The pristine generation has an age of 80.2 ± 1.6 Ma from a metagabbro, and 76.4 ± 2.1 Ma from a metaplagiogranite dyke. The skeletal, low Th/U zircon generation yields an age of 52.4 ± 0.8 Ma. The Upper Cretaceous zircons are interpreted to date emplacement of the magmatic protoliths in a small segment of oceanic crust. The Eocene age, however, dates a zircon recrystallization event, which possibly coincides with high solubility and mobility of HFSE-elements in a high-pressure aqueous fluid phase. Intergrowth relations between zircon and peak-metamorphic garnet, and excellent agreement of the U-Pb ages with white mica Ar-Ar ages of the same samples support, that Eocene is the true age of high-pressure metamorphism on Syros
Articolo in rivista - Articolo scientifico
geochronology, paragonite, zircon, petrology, eclogite
English
1977
2002
26
Tomaschek, F., Kennedy, A., Villa, I., Lagos, M., Ballhaus, C. (2003). Zircons from Syros, Cyclades, Greece - Recrystallization and mobilization of zircon during high pressure metamorphism. JOURNAL OF PETROLOGY, 44(11), 1977-2002 [10.1093/petrology/egg067].
Tomaschek, F; Kennedy, A; Villa, I; Lagos, M; Ballhaus, C
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/3735
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