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Accession number;04A0874357
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| Title;Osumilite and spinel+quartz from Sri Lanka: Implications for UHT conditions and retrograde P-T path |
| Author;
SAJEEV K
(Chonbuk National Univ., Chonju, Kor)
OSANAI Y
(Kyushu Univ., Fukuoka, Jpn)
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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.5;PAGE.320-327(2004)
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| Figure&Table&Reference;FIG.7, TBL.1, REF.36 |
| Pub. Country;Japan |
| Language;English |
| Abstract;We report here the occurrence of osumilite as fine isolated inclusions in garnet porphyroblasts from a granulite facies rock in the southwestern part of the Highland Complex in Sri Lanka. Garnet porphyroblasts in the matrix are partly rimmed by sillimanite-biotite-K-feldspar assemblage as well as cordierite-K-feldspar-quartz assemblage. Spinel coexisting with quartz is also observed in the same sample. The pressure-temperature condition must be above 950.DEG.C. at around 7kbar pressure, on the basis of osumilite stability in KFMASH system. The cooling and decompression continued down to 850.DEG.C., into the biotite-sillimanite-K-feldspar-quartz stability field. During decompression fX(X=O2) must have increased leading to the stability of Zn-rich-spinel with quartz after cordierite. Our findings provide direct evidence for ultrahigh-temperature (UHT) metamorphic conditions in southwestern Highland Complex, and also suggest the existence of a possible UHT zone within the high-grade terrane of Sri Lanka. (author abst.) |
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