Paleomagnetism of c. AD 1314 Kaharoa rhyolite and the New Zealand paleosecular variation master curve NZPSV2007

Rhyolite domes were extruded on Mt Tarawera summit during the Kaharoa eruption episode radiocarbon dated at AD 1314 +/- 12 yr. Interiors of the domes are well exposed in deep craters formed during the AD 1886 Tarawera eruption. Paleomagnetic studies have been carried out on 41 oriented cores obtained from 5 sites within Wahanga and Crater Domes. The fresh rhyolite rock is consistently strongly magnetised with NRM of 1-12 A/m. Progressive thermal demagnetisation was applied to every sample. Consistently unicomponent Zijderveld trajectories were obtained, giving a mean paleofield direction of declination 354.6 degrees, inclination -61.2 degrees, alpha(95) 4.3 degrees during emplacement of the rhyolite. These results impose a strong constraint on the paleosecular variation master curve for New Zealand, which is accordingly revised. The similarity of paleofield directions for Crater Dome (extruded early in the Kaharoa eruption sequence) and Wahanga Dome (extruded late in the sequence) is consistent with little time having separated extrusion of these two domes.