Rb-Sr geochronology of the Nobel gneiss and McKellar gneiss, Parry Sound region, Ontario.

The Nobel granitic gneiss, located in the Britt domain, gives a Rb/Sr whole-rock age of 1330 + or - 44 m.y. with an initial ⁸⁷Sr/⁸⁶Sr value of 0.7033. This agrees with a previously published zircon U/Pb age and is interpreted as the time of intrusion of the unit. The McKellar gneiss, located in the Parry Sound granulite domain, gives a Rb/Sr whole-rock age of 1241 + or - 12 m.y., interpreted as the time of Rb/Sr closure for the granulite grade …