气候变化领域集成服务门户(CCPortal): Two high-pressure metamorphic events; Variscan and Alpine; dated by Lu–Hf in an eclogite complex of the Austroalpine nappes (Schobergruppe; Austria)

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DOI	10.1007/s00531-019-01708-8
	Two high-pressure metamorphic events; Variscan and Alpine; dated by Lu–Hf in an eclogite complex of the Austroalpine nappes (Schobergruppe; Austria)
	Hauke M.; Froitzheim N.; Nagel T.J.; Miladinova I.; Fassmer K.; Fonseca R.O.C.; Sprung P.; Münker C.
发表日期	2019
ISSN	14373254
起始页码	1317
结束页码	1331
卷号	108 期号:4
英文摘要	The Eo-Alpine high-pressure belt in the Austroalpine nappes consists of pre-Mesozoic basement rocks overprinted by eclogite-facies metamorphism during the Late Cretaceous. Parts of this basement were already eclogitized during the Variscan orogeny. Lu–Hf geochronology allowed to identify two high-pressure events in an eclogite body in the Schobergruppe, an Austroalpine basement complex south of the Tauern Window. Two samples from closely neighboring outcrops were studied. Both contain two garnet generations. In one sample, PRI3, garnet belongs almost exclusively to the younger (Alpine) generation with only rare preservation of relic cores. In the other sample, PRI4, Variscan garnet is merely coated by a thin rim of the second, Alpine generation, which is in equilibrium with the high-pressure matrix assemblage. In PRI3, two-point garnet-whole rock ages scatter between ~ 97 and ~ 104 Ma, reflecting Alpine garnet growth with minor contamination by a Variscan component. In PRI4, two-point isochrons yield ages between ~ 300 and ~ 313 Ma. The limited spread in these ages suggests minor contamination by Alpine garnet rims. We propose 97 Ma as the maximum age for Alpine metamorphism, which is close to previously determined ages from other parts of the high-pressure belt, and 313 Ma as a minimum age for Variscan metamorphism. Thermodynamic modelling infers that eclogite-facies conditions were reached in both events; during the Late Cretaceous, these were ca. 1.9 GPa/650 °C. Variscan high-pressure conditions in PRI4 are inferred from the amount of garnet in the sample, which indicates at least 1.6 GPa. We propose that the occurrence of Alpine versus Variscan garnet in eclogites depends on the intensity of Variscan and post-Variscan retrogression: the more prograde, Variscan garnet was removed during retrogression, the more garnet grew during the Alpine cycle. © 2019, Geologische Vereinigung e.V. (GV).
英文关键词	Austroalpine basement; Eastern Alps; Eclogites; Eo-Alpine orogeny; High-pressure metamorphism; Lu–Hf geochronology; Variscan orogeny
语种	英语
scopus关键词	eclogite; geochronology; hafnium; Hercynian orogeny; high pressure; lutetium; metamorphism; orogeny; Austria
来源期刊	International Journal of Earth Sciences
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/147833
作者单位	Institute of Geosciences and Meteorology, University of Bonn, Meckenheimer Allee 169, Bonn, 53115, Germany; Department of Geoscience, University of Aarhus, Høegh-Guldbergs Gade 2 Building 1672, 313, Aarhus C, 8000, Denmark; Institute of Geology and Mineralogy, University of Cologne, Zülpicher Straße 49b, Cologne, 50674, Germany; Paul Scherrer Institute (PSI), OHLA/128, Villigen, 5232, Switzerland; Institute of Earth Sciences, NAWI Graz Geocenter, University of Graz, Heinrichstraße 26, Graz, 8010, Austria
推荐引用方式 GB/T 7714	Hauke M.,Froitzheim N.,Nagel T.J.,等. Two high-pressure metamorphic events; Variscan and Alpine; dated by Lu–Hf in an eclogite complex of the Austroalpine nappes (Schobergruppe; Austria)[J],2019,108(4).
APA	Hauke M..,Froitzheim N..,Nagel T.J..,Miladinova I..,Fassmer K..,...&Münker C..(2019).Two high-pressure metamorphic events; Variscan and Alpine; dated by Lu–Hf in an eclogite complex of the Austroalpine nappes (Schobergruppe; Austria).International Journal of Earth Sciences,108(4).
MLA	Hauke M.,et al."Two high-pressure metamorphic events; Variscan and Alpine; dated by Lu–Hf in an eclogite complex of the Austroalpine nappes (Schobergruppe; Austria)".International Journal of Earth Sciences 108.4(2019).