GAYATRI N AKOLKAR
Articles written in Journal of Earth System Science
Volume 129 All articles Published: 25 September 2020 Article ID 0198 Research Article
GAYATRI N AKOLKAR MANOJ A LIMAYE
In this work, the calc-silicate rocks affiliated to the ‘Kadana Formation’, a youngest formation of the Lunavada Group have been investigated. These rocks are found to be embedded within associated rock types, viz., quartzites and metapelites in the form of isolated lensoidal bodies. Contact metamorphic textures and the typical mineral assemblage, viz., Act +Di + Cal + Qtz + Ttn $\pm$ Mc $\pm$ Pl $\pm$ Bt $\pm$ Ep $\pm$ Scp $\pm$ Chl with minor proportion of apatite, zircon and opaques can be observed in these calc-silicates. Major oxides, trace and rare earth elements were analysed to investigate the protolith type, provenance and tectonic setting of these rocks. Protolith must be calcareous sandstone with varied proportion of clay and deposited in shallow water environment as revealed by CaO, Al$_{2}$O$_{3}$ and FeO+MgO and Al–Zr–Ti ternary diagram, respectively. Low to moderate weathering of source rocks has been indicated by A–CN–K ternary diagram. Th/Sc
$\bf{Highlights}$
$\bullet$The calc-silicate rocks show major oxides, trace and rare earth element compositions which are very similar to those of their post-archean counterparts. Similarly, in the REEs
$\bullet$Data plotted in Al$_{2}$O$_{3}$, CaO and FeO + MgO diagram of Barton
$\bullet$CIA studies are pointing towards the low to moderate weathering of the source under the cold and arid conditions.
$\bullet$The Th–Sc characteristics (Th/Sc > 1) support a predominantly continental source for these rocks; similarly, values of Zr/Sc indicate a moderate amount of sediment recycling.
$\bullet$Higher abundances of incompatible elements imply predominantly felsic rocks in the source, which is also supported by LREE-enriched patterns. As per the Th/Co
$\bullet$The study concludes that the primary sediments for the calc-silicates of the Lunavada Group were deposited in an active continental margin setting.
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