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

Krenn, K; Bauer, C; Proyer, A; Mposkos, E; Hoinkes, G

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	https://dspace.lib.ntua.gr/xmlui/handle/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