Mica samples from pegmatites and mica separates from associated rocks, belonging to the Dharwar formations of Kolar and the vicinity of Bangalore have been dated by Rb–Sr and K–Ar methods. The results by both methods show good concordance and support the concept of a plutonic-metamorphic event in this region in the interval 2050–2300 m.y. Muscovites of Nellore (Eastern Ghats cycle) and lepidolites from Hazaribagh (Satpura cycle) have also been analyzed to yield ages of 1500 m.y. and 900 m.y. respectively.

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