Kaingaroa Ignimbrite, Taupo Volcanic Zone, New Zealand: evidence for asymmetric caldera subsidence of the Reporoa Caldera

The 0.23 Ma Kaingaroa Ignimbrite represents the only large-scale eruption from Reporoa Caldera, Taupo Volcanic Zone, New Zealand. A combination of detailed volcanology and lithic componentry of the Kaingaroa Ignimbrite and morphological and geophysical data on the caldera has constrained the development of Reporoa Caldera. The Kaingaroa Ignimbrite eruption evolved from a single vent during the initial stages of the eruption, to a trapdoor caldera with the opening up of fractures coincidental with regional faults along the eastern margin, from which the main part of the Kaingaroa Ignimbrite was erupted. Finally, caldera collapse occurred during the later stages of the eruption. Asymmetric ignimbrite and facies distribution is interpreted as largely resulting from eastward-directed pyroclastic flows erupted during intially asymmetric caldera subsidence.