Palaeomagnetism, radiometric age and geochemistry of an adamellite at Yetholme, N.S.W.

The adamellite that outcrops at Yetholme in central western New South Wales is a satellite body of the Bathurst batholith. Fresh exposures have recently become available in a new road cutting. Abundant potassium‐feldspar megacrysts and mafic xenoliths occur in the adamellite and it is cut by aplite and dolerite dykes. The fresh rocks have been sampled for petrological and geochemical studies and for radiometric dating. Palaeomagnetic data from three rock types (adamellite, xenoliths, and dolerite) indicate stability of magnetization. Results of all these studies complement each other. Radiometric ages (K‐Ar) for the adamellite and dolerite confirm a Late Carboniferous age (312 m.y.) of emplacement, as does a Rb‐Sr age (325 ± 17 m.y.) determination on the aplite. These confirm three earlier radiometric age determinations for the Bathurst batholith and country rocks and stratigraphic age estimates. The palaeomagnetic directions from these three (Yetholme) rock types agree well with other palaeomagnetic data from Carboniferous rocks from the Newcastle to Tamworth region of New South Wales. The palaeogeomagnetic pole position obtained from the Upper Carboniferous Yetholme adamellite was at 59°S, 150°E (dp = 5°, dm = 8°).