Journal ArticleDOI
Glaucophanites and eclogites from Val Chiusella, Sesia-Lanzo zone (Italian Alps)
TLDR
In this article, the critical reaction 1 zoisite + 1 glaucophane ⇆ 1.2 omphacite+0.8 H2O was investigated in the metamorphic assemblages of Val Chiusella.Abstract:
In the metabasites of Val Chiusella, metamorphic assemblages are present, corresponding to the glaucophane schist facies, i.e. garnet glaucophanites to omphacite-garnet glaucophanites, as well as to the eclogite facies, i.e., glaucophane eclogites, eclogites, and omphacite felses. Both groups of assemblages are divided by the critical reaction 1 zoisite +1 glaucophane ⇆ 1.2 omphacite+0.8 garnet+0.7 paragonite +1.4 quartz+0.8 H2O. From textural evidence it is clear that in the investigated area this reaction proceeded to the right according to a prograde metamorphism. Correspondingly, K
garn-cpx
D(Fe/Mg) values of coexisting garnet-omphacite pairs in the glaucophane schist facies assemblages are higher than in the eclogite facies assemblages and reflect a temperature increase from about 450 ° C to about 550 ° C at minimum water vapour pressures of 12 to 16 kb.read more
Citations
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Journal ArticleDOI
Phase relations of epidote-blueschists
TL;DR: In this paper, phase diagrams have been computed for minerals in the system NCMASH, using the optimised thermodynamic data-base of Berman (1988) augmented by data on glaucophane and pumpellyite, to illustrate the relationships between rocks containing epidote and sodic amphibole and those containing assemblages characteristic of neighbouring metamorphic facies.
Journal ArticleDOI
Dating of eclogite-facies zircons: the age of Alpine metamorphism in the Sesia–Lanzo Zone (Western Alps)
TL;DR: In this article, the age of metamorphic zircon rims from a hydrothermal vein is interpreted as dating the prograde formation of the vein at temperatures well below 550°C.
Journal ArticleDOI
Paragenesis of sodic pyroxene-bearing quartz schists: implications for the P-T history of the Sanbagawa belt
TL;DR: In this paper, two types of zonal structure were observed in relatively coarse-grained sodic pyroxenes in the matrix, one type is characterized by increasing X676Jd from core to rim, the other type by decreasing X fixmeJdfrom core-to-rim.
Journal ArticleDOI
From granulites to eclogites in the Sesia zone (Italian Western Alps): a record of the opening and closure of the Piedmont ocean
J. M. Lardeaux,Maria Iole Spalla +1 more
TL;DR: In this paper, a detailed mineralogical study of eclogitized acid and basic granulites, and related amphibolites, is presented, and the authors propose to relate the pre-Alpine granulite and post-granulite retrograde evolution to the Permo-Jurassic extensional regime.
Journal ArticleDOI
Lawsonite blueschists and lawsonite eclogites as proxies for palaeo‐subduction zone processes: a review
Tatsuki Tsujimori,W. G. Ernst +1 more
TL;DR: Lawsonite-bearing metamorphic/metasomatic rocks form at high-pressure-ultrahigh pressure (HP-UHP) and low-temperature (LT) conditions, commonly in Pacific-type subduction zones.
References
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Journal ArticleDOI
An interlaboratory comparison of piston-cylinder pressure calibration using the albite-breakdown reaction.
W. Johannes,Peter M. Bell,Ho-kwang Mao,A. L. Boettcher,D. W. Chipman,J. F. Hays,Robert C. Newton,F. Seifert +7 more
TL;DR: In this article, an attempt is made to compare pressure calibration methods among several laboratories in an unbiased way to produce some indication of the bandwidth of observations on the pressure of an equilibrium reaction where sources of discrepancy not resulting from pressure calibration are likely to have been eliminated.
Journal ArticleDOI
Experimental determination of the reaction paragonite=jadeite+kyanite+H 2 O, and internally consistent thermodynamic data for part of the system Na 2 O−Al 2 O 3 −SiO 2 −H 2 O, with applications to eclogites and blueschists
TL;DR: In this article, the upper pressure stability of paragonite in the temperature range 550-740 ° C has been investigated and the experimental brackets are thermodynamically consistent with the lower pressure reversals.
Journal ArticleDOI
Experimental studies on glaucophane: An analysis of present knowledge
TL;DR: In this article, a review of the evolution of experimental work on synthetic, end-member, iron-free glaucophane, Na2Mg3Al2SigO22(OH)2, leads to the conclusion that it is unlikely that an amphibole of this composition has yet been synthesized.
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