Environmental and Climatic Responses to Two Large Explosive Eruptions from Taupō Volcano, New Zealand

• Main Author: Stephen Piva
• Format: Thesis
• Language: unknown
• Published: 2023
• Subjects: Palaeontology (incl. palynology); Volcanology; Natural hazards; Quaternary environments; Volcanic eruptions; Palynology; Taupō volcano; School: School of Geography; Environment and Earth Sciences; 370512 Volcanology; 370506 Palaeontology (incl. palynology); 370905 Quaternary environments; 370903 Natural hazards; 190403 Geological hazards (e.g. earthquakes; landslides and volcanic activity); Degree Discipline: Geology; Degree Name: Doctor of Science; Degree Level: Doctoral; Antarctic; New Zealand; Antarc*; ice core
• Online Access: https://doi.org/10.26686/wgtn.24848067; https://figshare.com/articles/thesis/Environmental_and_Climatic_Responses_to_Two_Large_Explosive_Eruptions_from_Taup_Volcano_New_Zealand/24848067

Two caldera forming ignimbrite eruptions of Taupō volcano (New Zealand) are among the most violent, powerful, and complex known Late Quaternary volcanic eruptions on Earth. The >530 km3 (dense rock equivalent [DRE]) ~25.5 ka Ōruanui, and 35 km3 (DRE) 232 ± 10 CE Taupō eruptions are world class examples of large volume explosive volcanism. Preservation of diagnostic pyroclastic material in Southern Hemisphere terrestrial, marine, and glacial palaeoarchives enable high resolution investigation of environmental and climatic proxy records to contextualise and assess the regional to global scale effects of these events. In this thesis, millimetre scale palynological records of three North Island lacustrine sediment cores were developed, and complemented by an investigation of Antarctic ice core records, to assess the environmental and climatic impacts of the Ōruanui and Taupō eruptions over short timescales of years to decades. Deposits of the Ōruanui eruption (known as the Kawakawa Ōruanui Tephra [KOT]) represent an important time stratigraphic marker for the Last Glacial Maximum (LGM) within terrestrial and marine sedimentary archives across New Zealand. However, the top contact of such deposits, and therefore the immediate post eruptive effects, are generally missing near the eruption centre, and even where preserved, previous studies were unable to detect and quantify any palaeoecological responses to this event. An intact 3 cm thick layer of the KOT was preserved in the continuous, high resolution lacustrine sedimentary sequence of Onepoto maar (Auckland), located ~240 km upwind from Taupō volcano. Targeted palynological and geochemical analyses of sediments bracketing the KOT at 1 mm intervals resolved a temporary (<10 years) ashfall induced partial defoliation of tall trees in the forest canopy and margins (predominantly Fuscospora group), and a longer term (~60 years) expansion of wetland and littoral habitats surrounding the palaeolake. Short lived volcanogenic cooling inferred from Antarctic ice core ...