Multi-method constraints on the age and timescale of silicic small-volume eruptions of Puketerata Volcanic Complex, Taupō Volcanic Zone, New Zealand

Abstract

Accurate dating of young eruptions from explosive volcanoes is essential for forecasting future eruptions and for defining the hazardscape of volcanic fields. However, precise dating of Quaternary eruptions is often challenging due to limited number of applicable dating methods or lack of datable eruptive phases. Moreover, small volume eruptions (e.g., monogenetic type), despite their significance on regional scale, have traditionally deserved less attention than their large volume counterparts. Puketerata is a maar-lava dome complex in the central Taupō Volcanic Zone (New Zealand), encompassing mafic and silicic phreatomagmatic eruptions with well-preserved pyroclastic deposits sourced from closely spaced vents. Its most recent activity is estimated to ca. 16 ka based on medial and distal stratigraphic surveys. Here, we carried out two independent age determinations and an additional paleomagnetic analysis on the volcanic succession of the Puketerata maar-lava dome complex with an aim to unravel the timing of volcanic activity. Combined U-Th disequilibrium and (U-Th)/He dating of zircon from two lava domes yielded eruption ages of 11.3 ± 2.6 ka and 11.3 ± 1.7 ka, which are concordant with the radiocarbon ages of 11.3–11.7 ka obtained on charcoal from the base of the pyroclastic sequence. Paleomagnetic data on the lavas from the two lava domes suggest at least ~ 100 years difference between their emplacements. Our geochronological results and new stratigraphic observations suggest that the volcanic/magmatic history of the Puketerata is complex with multiple eruptions within a small, confined area, where the most recent eruptions occurred only at ca. 11.5 ka, which is significantly younger than previously thought. This provides an additional datum for volcanic hazards assessment and stratigraphic correlations in New Zealand.Graphical