Conditions P-T du métamorphisme anté-alpin dans la °seconde zone dioritokinzigitique° (Zone Sesia-Lanzo, Alpes occidentales)  [P-T conditions of the pre-Alpine metamorphism in the secondary diorite-kinzigite zone, Sesia-Lanzo Zone, Western Alps]

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Alternate Title:P-T conditions of the pre-Alpine metamorphism in the secondary diorite-kinzigite zone, Sesia-Lanzo Zone, Western Alps
Authors:Vuichard, J. P.
Author Affiliations:Primary:
Univ. Rennes, Lab. Tectonique, Rennes 35042, France
Volume Title:Schweizerische Mineralogische und Petrographische Mitteilungen Bulletin Suisse de Minéralogie et Pétrographie
Source:Schweizerische Mineralogische und Petrographische Mitteilungen = Bulletin Suisse de Minéralogie et Pétrographie, 67(3), p.257-271. Publisher: Stäubli Verlag AG, Zurich, Switzerland. ISSN: 0036-7699
Publication Date:1987
Note:In French with English summary. 3 p. refs.; illus. incl. 8 tables
Summary:This zone (IIDK) is an Austroalpine unit located in the N part of the Sesia-Lanzo zone and is one of the uppermost units of the internal W Alps. It contains well-preserved high T parageneses of prealpine age. A detailed study of metapelitic rocks is presented. The high T paragenesis consists of quartz + plagioclase + garnet + biotite + sillimanite + ilmenite. EPMA shows that garnet is zoned; plagioclase is more calcic when included in garnet than in the matrix; and biotite is generally more Mg-rich in garnet than in the matrix. Equilibrium conditions of the prealpine assemblage have been estimated at approx 6 kbar and 700-750 degrees C. Water activity in the fluid phase was < 1. P-T conditions of the prealpine metamorphism are very similar in the IIDK and in the Ivrea zone. The IIDK belongs to the group II granulites of Pin & Vielzeuf (1983) classification. Like the Ivrea zone the IIDK was probably located at the bottom of the Southalpine crust before the alpine collision started. [R.E.S.]
Subjects:Diorites; Facies; Granulite facies; Granulites; Igneous rocks; Kinzigite; Metamorphic rocks; Metamorphism; P-T conditions; Petrology; Plutonic rocks; Retrograde metamorphism; Alps; Europe; Italy; Piemonte Italy; Sesia-Lanzo Zone; Southern Europe; Western Alps
Abstract Numbers:92M/3626
Record ID:1990071823
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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