Early Proterozoic 87Rb-86Sr Model Ages of Pegmatitic Muscovite from Rare Metal-bearing Granite-Pegamtite System of Kawadgaon, Bastar Craton, Central India

Seven muscovite mica separates from the rare metal pegmatites of Kawadgaon, Bastar Craton, Central India, give model 87Rb-86Sr ages ranging from 2330 to 1850 Ma. The oldest age of the muscovite almost overlaps within 20 error with the age (2497k152 Ma) of the parent fertile granites. The data suggest possible derivation of pegmatites shortly after the emplacement of Kawadgaon granites at ca. 2500 Ma. Most of the muscovite ages (n = 6) indicate tectonomagmatic ages after pegmatite injections. The 87Sr/86Sr ratio (0.7142) of granites suggests their derivation from crustal material.