First detection in Australia of cryptotephra likely to be derived from the 25.6 ka Ōruanui supereruption in New Zealand

Abstract

Cryptotephra subsampling techniques were used to identify a high concentration (c. 700 shards/g) of glass shards within the Yellow Marsh sediments in northwest Tasmania, Australia. Radiocarbon dating from the overlying sediments coupled with geochemical analysis of the glass shards indicate their similarity to the Kawakawa-Ōruanui Tephra (KOT), derived from the Ōruanui supereruption of 25,568 ± 232 cal yr BP (±2sd) from the Taupō Volcanic Zone, New Zealand. Although cryptotephra from this eruption has previously been identified in Antarctica and modelled to have been transported over parts of southern and eastern Australia, to date glass shards from this eruption have not been identified in Australia. If the correlation of the cryptotephra to the Ōruanui supereruption is correct, this finding has the potential to allow Last Glacial deposits in the SW Pacific (including those in Australia, New Zealand and Antarctica) to be irrefutably linked.