K-Ar ages of biotite and muscovite from Pangong metamorphic complex, Shyok suture zone, India: Implications for the youngest post-collision metamorphic event in Ladakh Himalaya

Thanh, Ngo Xuan and Itaya, Tetsumaru and Sajeev, Krishnan and Ahmad, Talat and Kojima, Satoru and Ohtani, Tomoyuki and Ehiro, Masayuki (2009) K-Ar ages of biotite and muscovite from Pangong metamorphic complex, Shyok suture zone, India: Implications for the youngest post-collision metamorphic event in Ladakh Himalaya. In: Journal of Mineralogical and Petrological Sciences, 104 (3). pp. 188-191.

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Abstract

The garnet-kyanite-staurolite and garnet-biotite-staurolite gneisses were collected from a locality within Lukung area that belongs to the Pangong metamorphic complex in Shyok valley, Ladakh Himalaya. The kyanite-free samples have garnet and staurolite in equilibrium, where garnets show euhedral texture and have flat compositional profile. On the other hand, the kyanite-bearing sample shows equilibrium assemblage of garnet-kyanite-staurolite along with muscovite and biotite. In this case, garnet has an inclusion rich core with a distinct grain boundary, which was later overgrown by inclusion free euhedral garnet. Garnet cores are rich in Mn and Ca, while the rims are poor in Mn and rich in Fe and Mg, suggesting two distinct generations of growth. However, the compositional profiles and textural signature of garnets suggests the same stage of P -T evolution for the formation of the inclusion free euhedral garnets in the kyanite-free gneisses and the inclusion free euhedral garnet rims in the kyanite-bearing gneiss. Muscovites from the four samples have consistent K-Ar ages, suggesting the cooling age (∼ 10 Ma) of the gneisses. These ages make a constraint on the timing of the youngest post-collision metamorphic event that may be closely related to an activation of the Karakoram fault in Pangong metamorphic complex.

Item Type:	Journal Article
Publication:	Journal of Mineralogical and Petrological Sciences
Publisher:	Japan Science and Technology Information Aggregator, Electronic
Additional Information:	copyright of this article belongs to Japan Science and Technology Information Aggregator, Electronic.
Keywords:	Pangong metamorphic complex;Garnet-kyanite-staurolite;K-Ar geochronology;Shyok suture;Ladakh Himalaya.
Department/Centre:
Date Deposited:	27 Aug 2009 06:04
Last Modified:	19 Sep 2010 05:41
URI:	http://eprints.iisc.ac.in/id/eprint/22269

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