A Reappraisal of the Pressure‐Temperature Path of Granulites from the Kerala Khondalite Belt, Southern India
2000
Abstract The Kerala Khondalite Belt (KKB) of South India is a pan‐African (ca. 600–500 Ma) regional granulite terrain that is composed of charnockites, khondalites, and migmatitic leptinitic gneiss. Peak assemblages in the KKB are characterized by orthopyroxene + garnet + K‐feldspar + magnetite + biotite + plagioclase + quartz in felsic to intermediate rocks and by orthopyroxene + cordierite + plagioclase + quartz or garnet + cordierite + sillimanite + feldspars + quartz in semipelites and pelites. Postpeak reaction textures in these assemblages often involve the production of cordierite and are consistent with a predominantly decompressional pressure‐temperature history at temperatures in excess of 700°C. Pressure‐temperature estimates based on garnet‐orthopyroxene thermobarometry are in the range of 6.5–7.5 kbar and 860°–920°C for localities close to and within the Achankovil Shear Zone, a prominent high‐grade, high‐strain zone on the northeastern margin of the KKB. For this northeastern subarea, peak t...
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