Late Quaternary volcanic ash stratigraphy of the Poukawa area, Central Hawke's Bay, New Zealand

Abstract

7 Holocene and 3 Late Pleistocene volcanic ashes (=tephras) are interbedded with peat, lake sediment, loess, and alluvial fan debris in the Poukawa Basin, Central Hawke's Bay. Identification is based on field appearance and stratigraphy, and where possible, is supported by mineralogy.

These tephras are from youngest to oldest: Kaharoa, Taupo, Mapara, Whakaipo, Waimihia, Whakatane, Hinemaiaia, Okareka, Kawakawa, and Tahuna.

new radiocarbon dates (new 1/2 life) were obtained: Waimihia 3380 ± 110 years B.P.; Whakatane 4740 ± 90 and 4770 ± 70 years B.P.; Hinemaiaia 5840 ± 140 and 5530 ± 100 years B.P. Assuming constant peat accumulation rates, estimated ages for the Mapara and Whakaipo Tephras are 2280 ± 20 and 2730 years B.P. respectively.

Keywords:

• Quaternary
• tephras
• stratigraphy
• Hawke's Bay
• C-14