Radiometric evidence of the Kanimblan Orogeny in southeastern Queensland and the age of the Neranleigh-Fernvale group

Abstract

Conventional K-Ar geochronology and the ⁴⁰Ar/³⁹Ar method in which the ratio of radiogenic argon to postassium is determined by measurement of ³⁹Ar produced by neutron irradiation are used to document the occurrence of the Upper Carboniferous Kanimblan Orogeny in the D'Aguilar Block and Beenleigh Block of southeastern Queensland.

Incremental evolution of argon by the heating of an irradiated sample of Neranleigh-Fernvale argillite and ⁴⁰Ar/³⁹Ar measurements on two hornblendes from alaskite clasts in the Neranleigh-Fernvale Group suggest that part of this unit may be as young as Lower Carboniferous.