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      https://www.ias.ac.in/article/fulltext/jess/091/01/0065-0073

    • Keywords

       

      Rb−Sr age; isochron; Ladakh batholith; Hercynian; Permo-Triassic; granite

    • Abstract

       

      The Gaik Granite is a part of the Ladakh batholith outcropping between Gaik and Kiari in NW Himalaya. This is a pink porphyritic granite rich in biotite and poor in hornblende. Rb-Sr analyses have been made on six whole-rock samples of the Gaik Granite. Though the samples are poorly enriched in radiogenic Sr, they define a reliable isochron corresponding to an age of 235±13 (2σ) m.y. and initial87Sr/86Sr ratio of 0·7081±0·0004 (2σ). Biotite, plagioclase and potash feldspar fractions separated from two of the samples have yielded a much younger mineral isochron at 30±1·5 m.y. indicating a nearly complete redistribution of Sr isotopes between mineral phases at a time much later than the primary emplacement of the granite. The present results show that at least some components of the Ladakh batholith are of Permo-Triassic age. These rocks were isotopically re-equilibrated on a mineral scale during Upper Oligocene in response to the Himalayan orogeny.

    • Author Affiliations

       

      J R Trivedi1 K Gopalan1 Kewal Kisharma2 K R Gupta2 V M Choubey2

      1. Physical Research Laboratory, Ahmedabad - 380 009, India
      2. Wadia Institute of Himalayan Geology, Dehra Dun - 248 001, India
    • Dates

       
  • Journal of Earth System Science | News

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