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Garnetiferous Metamorphic Rocks in Jaspa Granite, Himachal Pradesh, India:Implication of Tethyan Himalayan Metamorphism and Tectonics


Affiliations
1 Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
 

Studies on the magmatic enclaves, pelitic xenoliths and host Jaspa granite pluton outcropped in the Lahaul area, NW Himalaya, India illustrate that the rocks have undergone garnet-grade metamorphism. The P -T pseudosection modelling shows that the metamorphic mineral assemblage is stable in the P -T range ~4.5-7.3 kbar and ~440-500°C, matching quite well with the results obtained from the conventional geothermobarometers (5.7-8.6 kbar and 409-531°C). The observed garnet-grade metamorphism in and around the Jaspa pluton is proposed to be due to localized perturbation of high-temperature isotherms in the Tethys Himalaya, as a consequence of the Cenozoic tectono-thermal event during Himalayan orogeny. Further, the Haimanta group of Tethys Himalayan rocks in the Lahaul area has been interpreted to have attained right-way-up metamorphic field gradient.

Keywords

Garnet-Grade Metamorphism, Granite Pluton, Magmatic Enclaves, Pelitic Xenoliths.
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  • Garnetiferous Metamorphic Rocks in Jaspa Granite, Himachal Pradesh, India:Implication of Tethyan Himalayan Metamorphism and Tectonics

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Authors

S. S. Thakur
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
A. K. Singh
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
D. Rameshwar Rao
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
Rajesh Sharma
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
Subhajit Pandey
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India
Aliba Ao
Wadia Institute of Himalayan Geology, 33 GMS Road, Dehradun 248 001, India

Abstract


Studies on the magmatic enclaves, pelitic xenoliths and host Jaspa granite pluton outcropped in the Lahaul area, NW Himalaya, India illustrate that the rocks have undergone garnet-grade metamorphism. The P -T pseudosection modelling shows that the metamorphic mineral assemblage is stable in the P -T range ~4.5-7.3 kbar and ~440-500°C, matching quite well with the results obtained from the conventional geothermobarometers (5.7-8.6 kbar and 409-531°C). The observed garnet-grade metamorphism in and around the Jaspa pluton is proposed to be due to localized perturbation of high-temperature isotherms in the Tethys Himalaya, as a consequence of the Cenozoic tectono-thermal event during Himalayan orogeny. Further, the Haimanta group of Tethys Himalayan rocks in the Lahaul area has been interpreted to have attained right-way-up metamorphic field gradient.

Keywords


Garnet-Grade Metamorphism, Granite Pluton, Magmatic Enclaves, Pelitic Xenoliths.

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DOI: https://doi.org/10.18520/cs%2Fv115%2Fi8%2F1576-1583