Geothermometry and geobarometry of plagioclase-hornblende bearing assemblages

Plyusnina, L. P.

doi:10.1007/bf00374891

Cited by 176 publications

(91 citation statements)

References 9 publications

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“…This assemblage corresponds to temperatures between 560 and 600°C (Hbl-Pl thermometer of Blundy and Holland 1990). The calibrations of this thermometer by Plyusnina (1982) and Spear (1980) yield temperatures between 550 and 600º C; the Plyusnina calibration indicates a metamorphic pressure in excess of 8 kbar (unpublished data of the authors). A common feature in amphibolitized eclogites is the partial breakdown of kyanite enclosed in plagioclase to zoisite + margarite.…”

Section: Amphibolite Faciesmentioning

confidence: 92%

Geochronology of fluid-induced eclogite and amphibolite facies metamorphic reactions in a subduction–collision system, Bergen Arcs, Norway

Glodny

Kühn

Austrheim

2007

Contrib Mineral Petrol

118

100

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Rb-Sr multimineral isochron data for metamorphic veins allow to date separate increments of the mineral reaction history of polymetamorphic terranes. Granulite facies rocks of the Lindås nappe, Bergen Arcs, Norway, were subducted and exhumed during the Caledonian orogeny. The rocks show petrographic evidence for two distinct events of local fluid infiltration and vein formation, along fractures and shear zones. The first occurred at eclogite facies (15-21 kbar, 650-750 °C) and a later one at amphibolite facies conditions (8-10 kbar, 600°C). The presence of fluids enabled local metamorphic equilibration only near fluid pathways. In fluid-absent domains, preexisting assemblages were metastably preserved. This resulted in a heterogeneity of metamorphic signatures on m-to µm-scales. Well-preserved granulite facies rocks preserve their Proterozoic Rb-Sr mineral ages, as does the U-Pb system of zircon in most lithologies. Six Rb/Sr multimineral isochron ages for eclogite facies veins and their immediate wallrocks date the fluid-induced eclogitization at 429.9 ± 3.5 Ma (2σ, weighted average, MSWD = 0.39). An eclogite facies vein has yield metamorphic zircon with concordant U-Pb ages of 429 ± 3 Ma, identical to the U-Pb age of 427.4 ± 0.9 Ma for zircon xenocrysts in an amphibolite facies vein. Seven Rb/Sr mineral isochron ages date amphibolite-facies fluid infiltration at 414.2 ± 2.8 Ma (MSWD = 1.5), an age value testifying to residence of the rocks in the deep orogenic crust at temperatures >600°C for nearly 15 Ma. The new data show that Rb-Sr mineral isochron ages effectively date fluid-induced (re)crystallization events rather than stages of cooling. The direct link between isotopic ages and distinct petrographic equilibrium assemblages aids to constrain the evolution of rocks in the P-T-reaction-time space, which is essential for understanding exhumation histories and the internal dynamics of orogens in general.

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Section: Amphibolite Faciesmentioning

confidence: 92%

Geochronology of fluid-induced eclogite and amphibolite facies metamorphic reactions in a subduction–collision system, Bergen Arcs, Norway

Glodny

Kühn

Austrheim

2007

Contrib Mineral Petrol

118

100

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“…The MP metamorphic conditions for the M2 assemblages were defined by Zhong and Ding (1996) at P=8~10 kbar and T=800~900 (Opx-Cpx thermobarometer, Wood and Banno, 1973;Harley, 1984). ℃ According to the Am-Pl thermobarometer by Perchuk (1966) and Plyusnina (1982), the amphibolite-facies assemblages (M3) formed at P=4.5~6 kbar and T=650~700 (Zhong and …”

Section: Accepted Manuscriptmentioning

confidence: 99%

Timing of granulite-facies metamorphism in the eastern Himalayan syntaxis and its tectonic implications

Xu¹,

Zhang²,

Parrish³

et al. 2010

Tectonophysics

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. constrainted to be between 490 and ~600 Ma. Our data suggest that the granulite terrane in the eastern Himalayan syntaxis has an affinity with the Greater Himalayan Series. The HP granulite-facies metamorphic events in the eastern Himalayan syntaxis are distinct from ultrahigh pressure (UHP) metamorphic events in the western Himalayan syntaxis in both age and depth of burial. However, the metamorphic history of the eastern and western Himalayan syntaxises becomes similar after ~24 Ma. The Namche Barwa granulites appear to result from the underthrusting of the Indian plate lithologies beneath the Lhasa block during progressive collisional processes, followed by extrusion and/or exhumation that result from a slab breakoff of the Indian plate during the Miocene. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT

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“…Complementary P-T estimates of the amphibole-rich unit were obtained using the thermometer based on the cation exchange reaction of edenite (Holland and Blundy, 1994). Thermobarometers based on the contents of Ti and Al (VI) in amphibole were not used because of the absence of Zo and Ep in our samples (Raase, 1974;Plyusnina, 1982;Hammarstrom and Zen, 1986).…”

Section: Thermobarometric Methodsmentioning

confidence: 99%

Source and tectono-metamorphic evolution of mafic and pelitic metasedimentary rocks from the central Quetico metasedimentary belt, Archean Superior Province of Canada

Valli

2004

Precambrian Research

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Geothermometry and geobarometry of plagioclase-hornblende bearing assemblages

Cited by 176 publications

References 9 publications

Geochronology of fluid-induced eclogite and amphibolite facies metamorphic reactions in a subduction–collision system, Bergen Arcs, Norway

Geochronology of fluid-induced eclogite and amphibolite facies metamorphic reactions in a subduction–collision system, Bergen Arcs, Norway

Timing of granulite-facies metamorphism in the eastern Himalayan syntaxis and its tectonic implications

Source and tectono-metamorphic evolution of mafic and pelitic metasedimentary rocks from the central Quetico metasedimentary belt, Archean Superior Province of Canada

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