Sapphirine and corundum bearing ultrahigh temperature rocks from the Palghat-Cauvery Shear System, southern India
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Accession number;04A0874355
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| Title;Sapphirine and corundum bearing ultrahigh temperature rocks from the Palghat-Cauvery Shear System, southern India |
| Author;
KOSHIMOTO S
(Kochi Univ., Kochi, Jpn)
TSUNOGAE T
(Univ. Tsukuba, Ibaraki, Jpn)
SANTOSH M
(Kochi Univ., Kochi, 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.298-310(2004)
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| Figure&Table&Reference;FIG.8, TBL.1, REF.32 |
| Pub. Country;Japan |
| Language;English |
| Abstract;We report a new occurrence of sapphirine- and corundum-bearing silica-deficient Mg-Ai rocks from Paramati at the northern margin of the Palghat-Cauvery Shear System which define the Archaean-Proterozoic collisional boundary in southern India. Sapphirine here occurs as medium-grained euhedral to subhedral crystals enclosed within plagioclase and contains inclusions of spinel and sillimanite, and is locally intergrown with corundum, suggesting the reaction Spl+Sil.RAR.Spr+Crn. Temperatures estimated from sapphirine-spinel equilibria lie around 930-950.DEG.C., suggesting ultrahigh-temperature peak metamorphic conditions. Gedrite is also a common rock forming mineral in these rocks, and coexists with cordierite, corundum, and sillimanite. As gedrite is totally surrounded by cordierite, we infer a prograde reaction Ged+Sil.RAR.Crn+Crd+V. Lack of orthopyroxene in our samples suggests a decompressional P-T history following the prograde event. Our results suggest that the whole of northern Madurai Block as well as parts of the Palghat-Cauvery Shear System experienced ultrahigh temperature metamorphism followed by exhumation along a clockwise P-T path. (author abst.) |
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