Single Zircon 207Pb / 206Pb ages from the Garhwal Himalaya (India): Evidence for Paleo-Proterozoic magmatic activity in the Lesser and Higher Himalaya

We conducted single zircon age determinations on five samples from the Garhwal Himalaya, which represent a segment of the northern margin of the Gondwana. The results reveal extensive Paleo-Proterozoic volcanic and plutonic activity in this region. Data from an interbedded acid volcanic band indicates a depositional age of similar to 1.86 Ga for the upper part of the Berinag Group sediments. Three granitoid samples from the Jutogh-Munsiari Thrust sheet yielded Pb-207/Pb-206 ages between 1.85 and 1.74 Ga, interpreted as reflecting the crystallization age of these samples. In contrast our fifth sample, from a paragneiss located towards the base of the Vaikrita Thrust sheet, yielded a minimum age of <= 1.0 Ga, suggesting that Vaikrita represents the second distinct stratigraphic unit of the Higher Himalaya. We also noticed the absence of pronounced Archean to Earliest Proterozoic signatures in our data.