Potassium-argon ages of granites and metasediments from the Bounty Islands area, southwest Pacific Ocean

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Abstract
Potassium-argon dating of granites and a biotite-hornfels from the vicinity of the Bounty Islands indicates emplacement in Early Jurassic times, in the interval between the Tuhuan (Devonian — Carboniferous) and Rangi tata (Late Jurassic — Early Cretaceous) orogenies. Slight recrystallisation of a typical Bounty Platform argillite is dated as Early Triassic, which is much younger than the metamorphic ages (300–450 m.y.) that characterise the Lower Palaeozoic Greenland and Waiuta groups of the South Island, New Zealand. The age of recrystallisation of the Bounty Platform greywacke facies metasediments would thus seem to favour correlation with Permian to Lower Triassic sediments of the South Island, despite petrographic similarities to the Greenland and Waiuta rocks.