Radiometric evidence for the age of emplacement and cooling of the Murrumbidgee Batholith

Abstract
Most of the rocks of the Murrumbidgee Batholith have a Rb‐Sr age of 424 ± 2 m.y. This is considered to be the time of emplacement. A small difference in the ages (4 ± 2 m.y.) between the northern and southern parts of the batholith is attributed to thermal effects caused by a slightly later time of emplacement of some of the intrusions or to a short cooling interval. Final intrusive activity ended by 414 ± 4 m.y. Younger mineral ages for some intrusions are related to later local meta‐morphic effects.