Wairakei Formation, New Zealand: Stratigraphy and correlation

Abstract

We propose that various rhyolitic pumice deposits in the Taupo Volcanic Zone and beyond, that were previously called Wairakei Breccia, Waitahanui Breccia (in part), Oruanui (Pumice) Formation, and Kawakawa Tephra Formation, are the products of one large eruption at 20 000 years B.P. On grounds of precedence we name these voluminous deposits Wairakei Formation and suggest that other names be made redundant. Correlations across New Zealand and into the Southwest Pacific basin are presented, together with data from a stratigraphic drillhole near Taupo. The large volume of water inferred to have taken part in magma-water explosive interaction came from proto-Lake Taupo. The correlation of these 20 000 year old deposits, previously thought to be different ages, has a bearing on the age of the Huka Falls Formation and the late Quaternary history of the Taupo district and the Waikato River.

Maars to calderas: end-members on a spectrum of explosive volcanic depressions

“…Detailed studies of eruptive products of calderas such as Askja (Iceland; Self and Sparks, 1978;Carey et al, 2009) and Taupo (New Zealand; Self and Healy, 1987;Houghton et al, 2010) reveal deposits that are inferred to have resulted from simple magmatic volatile-driven processes to interaction of vesicular (and already fragmented?) melt with externally derived water (phreatoplinian).…”

Correlation, dispersal, and preservation of the Kawakawa Tephra and other late Quaternary tephra layers in the Southwest Pacific Ocean

“…For example, deposits from a c. 22 590 yr old event from Taupo have been variously ascribed to the Oruanui Ash and Breccia, Wairakei Formation, Tiromoana Ash, Aokautere Ash, Scinde Island Ash, Rekohu Ash, and Kawakawa Tephra (e.g., Vucetich & Howorth 1976;Kohn 1979;Campbell 1986;Self & Healy 1987). The nomenclatural maze has been specifically addressed by Froggatt & Lowe (1990) in their review of late Quaternary silicic tephras, and we follow their recommendations.…”

A review of late Quaternary silicic and some other tephra formations from New Zealand: Their stratigraphy, nomenclature, distribution, volume, and age

“…In a detailed volcanological study of the c. 22 500 yr B.P. deposits, Self (1983) referred informally to the whole formation as the Wairakei formation, and has more recently argued for its formalisation (Self & Healy 1987). The term Wairakei is probably invalid for both Wairakei Breccia and Wairakei Formation , having been previously applied to Wairakei Ignimbrite (Beck & Robertson 1955).…”