A corundum and sapphirine paragenesis from the Limpopo Mobile Belt, southern Africa |
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| Authors: | PETER C HORROCKS |
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| Institution: | Department of Geology, University of the Witwatersrand, Jan Smuts Avenue, Johannesburg 2001, South Africa |
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| Abstract: | An assemblage consisting of corundum, sapphirine, spinel, cordierite, garnet, biotite and bronzite is described from the Messina area of the Limpopo Mobile Belt, and consideration given to its petrogenesis. Various geothermometers and geobarometers have been applied in an attempt to determine the temperatures and pressures of metamorphism.
A former coexistence of garnet and corundum is suggested to have developed during the earliest high pressure phase of the metamorphism, where temperatures exceeded 800°C and pressures as high as 10kbar may have been experienced. Subsequently, continuous retrograding reactions from medium pressure granulite facies at about 800°C and 8kbar towards amphibolite facies generated spinel, cordierite, sapphirine and possibly also bronzite. The most notable reaction was probably of the form: garnet + corundum = cordierite + sapphirine + spinel. |
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| Keywords: | Key-words: corundum garnet Limpopo Mobile Belt metamorphism sapphirine |
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