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

Toshiaki Tsunogae, Dirk D. Van Reenen

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

26 Citations (Scopus)

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 ultrahightemperature (UHT) metamorphism by rapid decompression, which was followed by further decompression and cooling. Mg-rich (X Mg ≃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 2 O. The symplectic sapphirine + quartz developed around staurolite probably implies decompression from P >14 kbar toward the stability of sapphirine + quartz at T ≃1000 °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.

Original languageEnglish
Title of host publicationOrigin and Evolution of Precambrian High-Grade Gneiss Terranes, with Special Emphasis on the Limpopo Complex of Southern Africa
PublisherGeological Society of America
Pages107-124
Number of pages18
ISBN (Print)9780813712079
DOIs
Publication statusPublished - 2011

Publication series

NameMemoir of the Geological Society of America
Volume207
ISSN (Print)0072-1069

ASJC Scopus subject areas

  • Geology

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