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Glaucophane schists and associated rocks from Sifnos (Cyclades, Greece): New constraints on the P-T evolution from oxidized systems

Groppo, Chiara; Forster, Margaret; Lister, Gordon; Compagnoni, Roberto

Description

The island of Sifnos (Cyclades, Greece) is famous for its spectacular blueschist-facies rocks and eclogites. Their very well preserved high-pressure assemblages are characterized by the occurrence of Fe+ 3-rich minerals such as aegirine-rich pyroxene, riebeckite-rich amphibole, magnetite and deerite. Therefore, the common model system NCFMASH (Na2O-CaO-FeO-MgO-Al2O3-SiO2 -H2O), in which all iron is assumed to be ferrous, is not sufficient to completely model these highly oxidized assemblages....[Show more]

dc.contributor.authorGroppo, Chiara
dc.contributor.authorForster, Margaret
dc.contributor.authorLister, Gordon
dc.contributor.authorCompagnoni, Roberto
dc.date.accessioned2015-12-08T22:22:21Z
dc.identifier.issn0024-4937
dc.identifier.urihttp://hdl.handle.net/1885/32534
dc.description.abstractThe island of Sifnos (Cyclades, Greece) is famous for its spectacular blueschist-facies rocks and eclogites. Their very well preserved high-pressure assemblages are characterized by the occurrence of Fe+ 3-rich minerals such as aegirine-rich pyroxene, riebeckite-rich amphibole, magnetite and deerite. Therefore, the common model system NCFMASH (Na2O-CaO-FeO-MgO-Al2O3-SiO2 -H2O), in which all iron is assumed to be ferrous, is not sufficient to completely model these highly oxidized assemblages. We propose new constraints on the P-T evolution of the glaucophane schists and associated rocks from Vroulidia Bay (northern Sifnos) using P-T isochemical diagrams (pseudosections) modelled for the oxidized N(K)CFMASHO system [Na2O-(K2O)-CaO-FeO-Fe2O3-Mg O-Al2O3-SiO2-H2O], and calculated using solid solution models involving Fe+ 3-end-members. The resulting P-T conditions could be fitted by a simple trajectory consisting of a smooth clockwise P-T loop, with two distinct high-pressure events at T = 450-500 °C, P > 2.0 GPa (assemblage A) and T = 525-565 °C, P > 2.1 GPa (assemblage B), respectively, followed by cooling and decompression. Geospeedometry based on40Ar/39Ar data, however, allows constraint as to the duration of individual thermal excursions associated with these events. Should these limits be taken into account, the P-T envelope derived in this paper encompasses a more complex P-T history, with individual excursions that potentially involve relatively short periods of temperature increase ± pressure variation.
dc.publisherElsevier
dc.sourceLithos
dc.subjectKeywords: blueschist facies; cooling; glaucophane; oxidation; P-T conditions; source rock; tectonic evolution; ultrahigh pressure metamorphism; Cycladas; Eurasia; Europe; Greece; Sifnos; Southern Aegean; Southern Europe Blueschist- and eclogite-facies; Oxidized system; P-T path; Pseudosection; Sifnos
dc.titleGlaucophane schists and associated rocks from Sifnos (Cyclades, Greece): New constraints on the P-T evolution from oxidized systems
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolumeOnline publication 2008
dc.date.issued2008
local.identifier.absfor040306 - Mineralogy and Crystallography
local.identifier.absfor040312 - Structural Geology
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationu4047674xPUB93
local.type.statusPublished Version
local.contributor.affiliationGroppo, Chiara, University di Torino
local.contributor.affiliationForster, Margaret, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationLister, Gordon, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationCompagnoni, Roberto, University di Torino
local.description.embargo2037-12-31
local.bibliographicCitation.startpageCHEMGE
local.bibliographicCitation.lastpage15519
local.identifier.doi10.1016/j.lithos.2008.10.005
dc.date.updated2016-02-24T10:32:39Z
local.identifier.scopusID2-s2.0-63049092586
local.identifier.thomsonID000265734000010
CollectionsANU Research Publications

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