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High-pressure and ultrahigh-temperature granulite-facies metamorphism of Precambrian high-grade terranes; case study of the Limpopo Complex

Toshiaki Tsunogae and Dirk D. van Reenen
High-pressure and ultrahigh-temperature granulite-facies metamorphism of Precambrian high-grade terranes; case study of the Limpopo Complex (in Origin and evolution of Precambrian high-grade gneiss terranes, with special emphasis on the Limpopo Complex of Southern Africa, Dirk D. van Reenen (editor), Jan D. Kramers (editor), Stephen McCourt (editor) and Leonid L. Perchuk (editor))
Memoir - Geological Society of America (2011) 207: 107-124

Abstract

We report new petrological data for granulites from the Central Zone of the Limpopo Complex, Southern Africa, and construct a prograde P-T path that traverses from high-pressure granulite-facies metamorphism to peak ultrahigh-temperature (UHT) metamorphism by rapid decompression, which was followed by further decompression and cooling. Mg-rich (X (sub Mg) approximately 0.58) staurolite enclosed within poikiloblastic garnet in an Mg-Al-rich rock from the Beit Bridge area is rarely mantled by a sapphirine + quartz corona, suggesting the progress of the prograde dehydration reaction: staurolite + garnet --> sapphirine + quartz + H (sub 2) O. The symplectic sapphirine + quartz developed around staurolite probably implies decompression from P >14 kbar toward the stability of sapphirine + quartz at T approximately 1000 degrees C along a clockwise P-T path. The orthopyroxene + sillimanite + quartz assemblage mantled by cordierite aggregates in a pelitic granulite from the same area also suggests extreme metamorphism and subsequent further decompression. Various corona textures such as kyanite + sapphirine, sapphirine + cordierite, and orthopyroxene + cordierite were probably formed as a result of decompression cooling events. The prograde high-pressure metamorphism and the following UHT event relate to the collisional tectonics of the Zimbabwe and Kaapvaal Cratons, which are associated with the amalgamation of microcontinents during the Neoarchean.


ISSN: 0072-1069
Coden: GSAMAQ
Serial Title: Memoir - Geological Society of America
Serial Volume: 207
Title: High-pressure and ultrahigh-temperature granulite-facies metamorphism of Precambrian high-grade terranes; case study of the Limpopo Complex
Title: Origin and evolution of Precambrian high-grade gneiss terranes, with special emphasis on the Limpopo Complex of Southern Africa
Author(s): Tsunogae, Toshiakivan Reenen, Dirk D.
Author(s): van Reenen, Dirk D.editor
Author(s): Kramers, Jan D.editor
Author(s): McCourt, Stepheneditor
Author(s): Perchuk, Leonid L.editor
Affiliation: University of Tsukuba, Graduate School of Life and Environmental Sciences, Earth Evolution Sciences, Tsukuba, Japan
Affiliation: University of Johannesburg, Department of Geology, Auckland Park, South Africa
Pages: 107-124
Published: 2011
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 79
Accession Number: 2011-102889
Categories: Igneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, geol. sketch map
S23°00'00" - S21°00'00", E28°00'00" - E32°00'00"
Secondary Affiliation: University of KwaZulu Natal, ZAF, South AfricaMoscow State University, RUS, Russian FederationUniversity of Johannesburg, ZAF, South Africa
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201152
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