Fluid entrapment and reequilibration during subduction and exhumation: A case study from the high-grade Nestos shear zone, Central Rhodope, Greece

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dc.contributor.author Krenn, K en
dc.contributor.author Bauer, C en
dc.contributor.author Proyer, A en
dc.contributor.author Mposkos, E en
dc.contributor.author Hoinkes, G en
dc.date.accessioned 2014-03-01T01:28:24Z
dc.date.available 2014-03-01T01:28:24Z
dc.date.issued 2008 en
dc.identifier.issn 0024-4937 en
dc.identifier.uri http://hdl.handle.net/123456789/18845
dc.subject Decrepitation en
dc.subject Fluid inclusions en
dc.subject Leakage en
dc.subject Rhodope Metamorphic Complex en
dc.subject Supercritical densities en
dc.subject.classification Geochemistry & Geophysics en
dc.subject.classification Mineralogy en
dc.subject.other deformation en
dc.subject.other diamond en
dc.subject.other exhumation en
dc.subject.other fluid inclusion en
dc.subject.other garnet en
dc.subject.other gneiss en
dc.subject.other P-T conditions en
dc.subject.other plane strain en
dc.subject.other quartz en
dc.subject.other recrystallization en
dc.subject.other shear zone en
dc.subject.other subduction en
dc.subject.other ultrahigh pressure metamorphism en
dc.subject.other Eastern Macedonia and Thrace en
dc.subject.other Eurasia en
dc.subject.other Europe en
dc.subject.other Greece en
dc.subject.other Rhodope en
dc.subject.other Southern Europe en
dc.subject.other Xanthi en
dc.title Fluid entrapment and reequilibration during subduction and exhumation: A case study from the high-grade Nestos shear zone, Central Rhodope, Greece en
heal.type journalArticle en
heal.identifier.primary 10.1016/j.lithos.2007.11.005 en
heal.identifier.secondary http://dx.doi.org/10.1016/j.lithos.2007.11.005 en
heal.language English en
heal.publicationDate 2008 en
heal.abstract A fluid inclusion study on metamorphic minerals of successive growth stages was performed oil highly deformed paragneisses from the Nestos Shear Zone at Xanthi (Central Rhodope), in which microdiamonds provide unequivocal evidence for ultrahigh-pressure (UHP) metamorphism. The correlation of fluid inclusion density isochores and fluid inclusion reequilibration textures with geothermobarometric data and the relative chronology of micro- and macro-scale deformation stages allow a better understanding of both the fluid and metamorphic evolution along the P-T-d path. Textural evidence for subduction towards the NE is recorded by the orientation of intragranular NE-oriented fluid inclusion planes and the presence of single, annular fluid inclusion decrepitation textures. These textures occur within quartz "foam" structures enclosed in an earlier generation of garnets with prolate geometries and rarely within recrystallized matrix quartz, and reequilibrated both in composition and density (luring later stages of exhumation. No fluid inclusions pertaining to the postulated ultrahigh-pressure stage for microdiamond-bearing garnet-kyanite-gneisses have yet been found. The prolate shape of garnets developed during the earliest stages of exhumation that is recorded structurally by (L >> S) tectonites, which subsequently accommodated progressive ductile SW shearing and folding up to shallow crustal levels. The majority of matrix kyanite and a later generation of garnet were formed during SW-directed shear under plane-strain conditions. Fluid inclusions entrapped in quartz during this stage of deformation underwent density loss and transformed to almost pure CO2 inclusions by preferential loss of H2O. Those inclusions armoured within garnet retained their primary 3-phase H2O-CO2 compositions. Reequilibration of fluid inclusions in quartz aggregates is most likely the result of recrystallization along with stress-induced, preferential H2O leakage along dislocations and planar lattice defects which results in the predominance of CO2 inclusions with supercritical densities. Carbonic fluid inclusions from adjacent kyanite-corundum-bearing pegmatoids and, the presence of shear-plane-parallel fluid inclusion planes within late quartz boudin structures consisting of pure CO2-fluid inclusions with negative crystal shapes, bear witness of the latest stage of deformation by NE-directed extensional shear. This study shows that the textures of early fluid inclusions that formed already during the prograde metamorphic path can be preserved and used to derive information about the kinematics of subduction that is difficult to obtain from other sources. The textures of early inclusions, together with later generations of unaltered primary and secondary inclusions in metamorphic index minerals that can be linked to specific deformation stages and even P-T conditions, are a welcome supplement for the reconstruction of a rather detailed P-T-cl path. (C) 2007 Elsevier B.V. All rights reserved. en
heal.publisher ELSEVIER SCIENCE BV en
heal.journalName Lithos en
dc.identifier.doi 10.1016/j.lithos.2007.11.005 en
dc.identifier.isi ISI:000259667400003 en
dc.identifier.volume 104 en
dc.identifier.issue 1-4 en
dc.identifier.spage 33 en
dc.identifier.epage 53 en

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