New Zealand Journal of Geology and Geophysics abstracts

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An occurrence of Tuhua Tephra in deep-sea sediments from offshore eastern North Island, New Zealand

B. Manighetti¹
A. Palmer²
D. Eden³
M. Elliot⁴

¹National Institute of Water and Atmospheric Research
P.O. Box 14 901
Wellington, New Zealand
email: b.manighett@niwa.co.nz

²Massey University
Private Bag 11 222
Palmerston North, New Zealand

³ c/- Landcare Research
Private Bag 11 052
Palmerston North, New Zealand

⁴Whangarei Boys High School
P.O. Box 5034
Whangarei, New Zealand

Abstract  We identify c. 7000 cal yr BP Tuhua Tephra in a marine sediment core from offshore eastern North Island, New Zealand. Its mineral assemblage includes aegirine, which is diagnostic for the Tuhua (Mayor Island) Volcanic Centre, and electron microprobe analyses of glass shards yield compositions close to published analyses of the tephra onshore, closer to the source. Associated radiocarbon ages on planktonic foraminifera from the core show that its age lies within the range previously determined for the caldera-forming event that generated Tuhua Tephra. This occurrence, >380 km southeast of the source, indicates that the dispersal of the ash was bi-directional, and that earlier estimates of this tephra’s volume may be conservative.

Keywords  Mayor Island; tephrochronology; Holocene; Tuhua Tephra; isopach

G02016; Received 19 March 2002; accepted 17 July 2003; online publication date 13 November 2003
New Zealand Journal of Geology & Geophysics, 2003, Vol. 46: 581–590
0028–8306/03/4604–0581 $7.00/0 © The Royal Society of New Zealand 2003

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