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Eclogite from Tattayyangarapettai-pavittiram area, Tamil Nadu
Published in -
Volume: 54
Issue: 43528
Pages: 169 - 182
An area of about 130 sq km covering an area between latitude 11°11′35.8″ to 11°5′00″ N and longitude 78°21′9″ to 78°28′5.4″ E around Tattayyangarapettai-Pavittiram (Trichy district, Tamil Nadu) has been mapped in the Southern Granulite Terrane of the Indian shield. The area studied reveals a number of rock types viz. BMQ, ultramafites, eclogite and amphibolite. The BMQ is mainly a quartz-magnetite association and shows metamorphic reconstitution. Ultramafic rocks of the area can be broadly subdivided into pegmatoid and non-pegmatoid types. The former mainly corresponds to pyroxenite whereas the latter comprises mainly websterite and hornblendite. The eclogitic rocks (consisting essentially of omphacite and garnet along with other accessory minerals) are spatially associated with amphibolite. Critical field and petrographic studies indicate amphibolite has been retrogressed/hydrated from eclogite. Major-element chemical data for the analysed samples when subjected to some standard screening parameters reveal that they are free of any post-crystallisation alteration. The chemical characters of ultramafic and eclogitic rocks (together with amphibolite) show evidence of normal magmatic differentiation from the common parent magma. Preliminary major-element modelling based on FeO-MgO cation mole percent plot reveals that ultramafic rocks have resulted from melt generated at high degree (≅60%) of partial batch melting of pyrolite. This magma on olivine fractionation might give rise to a derived melt parental to both eclogite and amphibolite. Investigated ultramafic, eclogite and amphibolite are linked to a common parental magma.
About the journal
JournalIndian Minerals
Open AccessNo