Mesozoic alkaline volcanism and Garrawilla Lavas near Mullaley, New South Wales

Abstract

Abstract Previous investigations had shown that the Garrawilla Lavas of the Coonabarabran‐Gunnedah region were of Mesozoic age and interbedded with Triassic and Jurassic sediments, but trachytes, trachybasalts and intrusive alkaline rocks occurring in the Mullaley—Tambar Springs—Rocky Glen area were still regarded as of Tertiary age. Recent investigations have revealed that the trachyte and trachy‐basalt flows, extruded from vents now occupied by intrusive alkaline rocks, are interbedded and continuous with the Garrawilla Lavas and form part of the Garrawilla Volcanism of Late Triassic or Early Jurassic age.