EarthRef.org Reference Database (ERR) -- Soengkono et al. 1992

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Soengkono et al. 1992

Soengkono, S., Hochstein, M.P., Smith, I.E.M. and Itaya, T. (1992). Geophysical evidence for widespread reversely magnetised pyroclastics in the western Taupo Volcanic Zone (New Zealand). New Zealand Journal of Geology and Geophysics 35(1): 47-55.

Low-altitude aeromagnetic data show that negative residual anomalies are widespread over the western Taupo Volcanic Zone, New Zealand. Paleomagnetic study of eight rhyolitic ignimbrite units and two lava flows which are exposed in this area, together with new K-Ar dates of four of the ignimbrite units, indicate that the two lava units and seven of the ignimbrite units were erupted during the Matuyama geomagnetic epoch (> 0.73 Ma B.P.) and suggest that rhyolitic volcanism in the western Taupo Volcanic Zone began as early as 1.6 Ma B.P. These results provide the basis for an interpretation of our aeromagnetic data which confirms the hypothesis that the magnetic anomalies observed in the western Taupo Volcanic Zone are caused by widespread, thick, reversely magnetised pyroclastic and lava flows. Magnetic modelling also allows thickness estimates of the younger, normally magnetised cover rocks which reach a maximum thickness of the order of 0.5 km in the Mangakino area. The magnetic structure of these volcanic rocks defines approximately the lateral extent of the Mangakino Volcanic Centre.

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Keywords
western taupo volcanic zone, k-ar dates, pyroclastic flows, paleomagnetism, stratigraphy, low-level aeromagnetic anomalies, residual magnetic anomalies, apatite

Journal
New Zealand Journal of Geology and Geophysics
http://www.rsnz.org/publish/nzjgg/

Publisher
The Royal Society of New Zealand