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Experimental evidence of phlogopitic mantle metasomatism induced by phengite dehydration

Bernd Wunder and Stefan Melzer
Experimental evidence of phlogopitic mantle metasomatism induced by phengite dehydration
European Journal of Mineralogy (August 2003) 15 (4): 641-647

Abstract

To simulate metasomatism at convergent plate boundaries, the process of phengite dehydration, followed by reactions between the expelled fluid and a model mantle material consisting of forsterite+enstatite, was investigated at subduction zone conditions using a piston cylinder apparatus. An experimental technique has been devised in which the fluid, which should be set free during phengite decomposition at about 950 degrees C and 3.5 GPa, would be triggered by a temperature gradient of about 50 K to infiltrate through a perforated Au-foil the hotter part of the capsule, containing the model mantle material. Crystallization of phlogopitic mica and Al-rich enstatite at the boundary phengite - (forsterite+enstatite), representing the "slab-mantle" contact region, indicates successful experimental simulation of mantle wedge metasomatism. Cs-Rb exchange coefficients K (sub D) , determined from compositions of newly formed phlogopitic micas, recrystallized phengite and of an amorphous phase, representing the quenched liquid, agree well with recently determined alkali-fractionation data between micas and fluid. The composition of the quenched liquid is rich in alkali, aluminium, silicon, and poor in magnesium, which is in agreement with fluid solubility data determined in earlier experimental studies at similar conditions.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 15
Serial Issue: 4
Title: Experimental evidence of phlogopitic mantle metasomatism induced by phengite dehydration
Affiliation: GeoForschungsZentrum Potsdam, Potsdam, Federal Republic of Germany
Pages: 641-647
Published: 200308
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 28
Accession Number: 2003-070555
Categories: Geophysics of minerals and rocks
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
Secondary Affiliation: Ceramics Research Centre, NLD, Netherlands
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200321
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