Ultrahigh-temperature metamorphism of the Southern Marginal Zone of the Archean Limpopo Belt, South Africa
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Accession number;04A0874350
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| Title;Ultrahigh-temperature metamorphism of the Southern Marginal Zone of the Archean Limpopo Belt, South Africa |
| Author;
TSUNOGAE T
(Univ. Tsukuba, Ibaraki, Jpn)
MIYANO T
(Univ. Tsukuba, Ibaraki, Jpn)
VAN REENEN D D
(Rand Afrikaans Univ., Zaf)
SMIT C A
(Rand Afrikaans Univ., Zaf)
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Journal Title;J Mineral Petrol Sci
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Journal Code:G0150B
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ISSN:1345-6296
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VOL.99;NO.4;PAGE.213-224(2004)
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| Figure&Table&Reference;FIG.7, TBL.1, REF.40 |
| Pub. Country;Japan |
| Language;English |
| Abstract;We report ultrahigh-temperature (T>950.DEG.C.) peak metamorphic conditions for the Southern Marginal Zone of the Archean Limpopo Belt in South Africa. Pelitic granulites of the zone have a typical mineral assemblage of garnet+biotite+orthopyroxene+cordierite+quartz+K-feldspar+plagioclase.+-.sillimanite, to which the latest geothermobarometers are applicable. The revised P-T conditions were obtained from a ternary feldspar geothermometer using antiperthitic feldspars in leucocratic granulite (920-980.DEG.C.), Al solubility in orthopyroxene in pelitic granulite (970-1020.DEG.C.), and a revised garnet-orthopyroxene geothermometer corrected for retro-grade Fe-Mg exchange (920-990.DEG.C.). The estimated peak temperature of metamorphism is about 100.DEG.C. higher than previously estimated based on conventional Fe-Mg exchange geothermometers (800-870.DEG.C.), and indicates a high geothermal gradient of -35.DEG.C./km in Archean continental lower crust. (author abst.) |
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