Abstract

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Title:: Metamorphism of High-pressure Granulites in Sand River Area of the Central Zone of Limpopo Belt, South Africa

Author(s):: ZHANG Hui-ming; ZHENG Chang-qing; XU Xue-chun; XU Jiu-lei; HAN Xiao-meng; ZHOU Xiao-ping; College of Earth Sciences, Jilin University, Changchun 130061, Jilin, China

Keywords:: metamorphism; high-pressure granulite; P-T path; Limpopo Belt; continental collision; Sand River area; South Africa

Abstract:: High-pressure mafic granulite with a peak mineral assemblage of garnet+clinopyroxene+quartz+ilmenite+magnetite was found in Sand River area of the central zone of Limpopo Belt, South Africa. The highpressure granulite experiences two stages of retrograde metamorphism. Early retrograde metamorphic stage is characterized by the appearance of orthopyroxene and plagioclase; late retrograde metamorphic stage is characterized by the appearance of amphibole. P-T estimates suggests that the peak metamorphic conditions are 820 ℃-900 ℃ and 13.5-15.4 kbar, which retrogress from the postpeak phase at 800 ℃-890 ℃and 8.8-11.2 kbar to the amphibolite facies at 540 ℃-650 ℃and 2.7-4.4 kbar. The three stages define a clockwise P-T path with near-isothermal decompression and cooling following the peak highpressure metamorphism. The granulites experience this clockwise P-T- paths, and usually develop in the continental collision setting. It means that the formation of high-pressure granulite relates to the crust fast stripping event after the collision of Zimbabwe craton and Kaapvaal craton. It is important for exploring the tectonic evolution in the central zone of Limpopo Belt.