Basanite cobbles in Pleistocene sediments in Central Otago and their implications for intraplate volcanism and Clutha River paleo-drainage

The occurrence of volcanic basanite cobbles in Pleistocene terraces at Galloway and the upper Clutha valley Central Otago, an area devoid known edifices, has implications for Cenozoic intraplate volcanism drainage region. We present petrographic, mineralogical, whole rock geochemical Sr-Nd-Pb isotopic data, as well 39Ar-40Ar date 24.4 ± 0.06 Ma, together with mineral analyses enclosed peridotite xenoliths. conclude from this dataset that these alkaline are most likely derived Alpine Dike Swarm northwest probably Lake Wanaka-Hawea-Luggate area, which extends field east its extent. pilotaxitic textures presence intersertal glass, along volume basanitic material, suggests source rocks were effusive, would make first such component requires emergent land time. implies River flowed through or over what is now Dunstan Range. young (late Pleistocene) age all basanite-bearing gravels means have been reworked several times before final deposition.