Abstract
The 1800a Taupo eruption was one of the most complex silicic eruptions worldwide within the past 5000 years. New work on phases 3 and 4, the Hatepe and Rotongaio ashes, has identified a mappable internal stratigraphy for each, enabling detailed isopach and isopleth measurements for subunits within the deposits. The new data indicate that the vent configuration for the Taupo eruption was more complex than previously thought and involved at least three sources on a NE-SW fissure centred on Horomatangi Reefs. Phases 1–3 of the eruption were from a southwestern vent(s), phase 4 from a northeastern source, and phases 5 and 6 probably from the Horomatangi Reefs area. A separate source for the Rotongaio ash (phase 4) helps explain the contrast between the pumice-rich phases of the eruption and the dense juvenile clasts of the Rotongaio ash. The Rotongaio magma resided in a separate, initially blind conduit and was degassing prior to and during earlier phases of the Taupo eruption. This new work on the Hatepe and Rotongaio ashes underscores the importance of a detailed stratigraphic framework in deciphering extremely fine-grained fall units of largescale sustained eruptions.
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Smith, R.T., Houghton, B.F. Vent migration and changing eruptive style during the 1800a Taupo eruption: new evidence from the Hatepe and Rotongaio phreatoplinian ashes. Bull Volcanol 57, 432–439 (1995). https://doi.org/10.1007/BF00300987
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DOI: https://doi.org/10.1007/BF00300987