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Microstructural controls on sites of metamorphic reaction; a case study of the inter-relationship between deformation and metamorphism

Richard Spiess and Tim H. Bell
Microstructural controls on sites of metamorphic reaction; a case study of the inter-relationship between deformation and metamorphism
European Journal of Mineralogy (February 1996) 8 (1): 165-186

Abstract

Compositional zoning in garnet porphyroblasts in two samples from the same outcrop in the Meran-Mauls Basement of the Austro-Alpine S Tyrol area show at least four growth stages, three of them being characterized by repetitive grossular zoning. The composition of these garnets varies from smooth to abrupt reductions in grossular and spessartine content (and a rise in X (sub Mg) ) in different microstructural sites. The transitions are smooth where the deformation event accompanying each phase of garnet growth was partitioned such that it was only weakly developed against the porphyroblast. However, they are abrupt where the deformation was more intensely developed against the earlier-formed garnet core due to dissolution of the rim of this portion. Both features indicate a strong microstructural control on the sites of porphyroblast growth and associated chemical reaction within syntectonically metamorphosed rocks. This control has resulted from the effects of partitioning of the deformation, and consequent variation in the intensity of foliation development, on both the access of material to the growth site in zones of progressive shortening plus dissolution of portions of the porphyroblast rims along zones of considerable progressive shearing.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 8
Serial Issue: 1
Title: Microstructural controls on sites of metamorphic reaction; a case study of the inter-relationship between deformation and metamorphism
Affiliation: Universita di Padova, Dipartimento di Mineralogia e Petrologia, Padova, Italy
Pages: 165-186
Published: 199602
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 36
Accession Number: 1996-024297
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map, 2 tables, block diag.
N46°34'60" - N47°46'00", E09°52'00" - E16°34'60"
N46°45'00" - N47°45'00", E10°04'00" - E12°43'00"
Secondary Affiliation: James Cook University, AUS, Australia
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199608
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