Tephrochronology and tephrostratigraphy of western taranaki (n108–109), New Zealand

Abstract

Ten newly named formations and members of ash and lapilli, erupted from Mt Egmont and the Pouakai Range, comprise the principal tephras mantling the western Taranaki landscape. They are overlain by nine restricted younger eruptives, previously described by Druce, which are also summarised in this paper. The Newall Ash and Lapilli are considered to have been deposited by nuées ardentes between 1500–1550 A.D., in contrast with the Burrell Lapilli, an airfall deposit of 1655 A.D. The newly named tephras include the “Egmont Shower”, here split into two separate formations, one considered to be less than (NZ1144) 6,970 ± 76 yr B.P., and the other between (NZ1144) and (NZŞ42) 16,100 ± 220 yr B.P. The underlying Saunders Ash is considered to be a nuée ardente deposit preserved between much thicker tephras, it contains charcoal dated (NZ942) at 16,100 ± 220 yr B.P. The other newly named tephras are richly allophanic, stratigraphically overlie the Rapanui Formation near New Plymouth and are thought to have been erupted from Mt Egmont. They overlie, with major disconformity, the oldest tephras described: the New Plymouth Ashes and Buried Soils, which form massive halloysite bearing deposits and were probably erupted from the Pouakai Range volcano. © 1972 Taylor & Francis Group, LLC.