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    Mapping hydrothermal alteration products on Mt Tongariro using multispectral satellite data, XRD analysis and reflectance spectroscopy : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science, at Massey University, Palmerston North, New Zealand
    (Massey University, 2016) Irwin, Matthew Eric
    The threat of a major collapse/landslide from a volcanic cone is a primary hazard of concern in the Tongariro National Park. The geologic record at Ruapehu and Tongariro volcanoes shows that past debris flows (lahars) have often contained a high proportion of alteration products. The present flanks of volcanoes in the Tongariro National Park have several hydrothermally altered zones that could be sources of future collapses. The purpose of this study was to assess the overall extent of alteration products and map altered zones on Mount Tongariro using field spectroscopy, X-Ray Diffraction analysis and analysis of satellite data. Hyperspectral data from the Hyperion sensor on the EO1 satellite and multi-spectral data from the Aster sensor on the EOS (Terra) satellite platform were acquired for the study area. The low signal to noise ratio of the Hyperion dataset meant the data was not suitable for analysis. The Aster data was chosen as it contains bands above 1500nm, the wavelength range where diagnostic abosorptions for minerals appear. There were analysis issues with the Aster scene but once the questionable bands were removed, areas of hydrothermal alteration were successfully identified and located. Mineral samples were collected from a variety of visually unique areas and reflectance spectra recorded using a portable spectroradiometer, along with the GPS locations. These samples were identified in the laboratory using the Spectral Analyst tool in ENVI and comparing them to the USGS, JPL and JHU mineral spectral libraries. The identification results from the field spectra and traditional X-Ray Diffraction (XRD) analysis of the samples were used to ground truth the satellite data. XRD was used to identify the alteration products and confirm the findings of the field spectra analysis. This enabled the selection of accurate end-members that were used to perform a classification of the imagery of the study area. The XRD and field spectroscopy data correlated well, and only the problem of several mixed minerals hindered a direct correlation. The alteration products form some of the least stable zones on the volcano. Smectite was identified in many of the samples which is a swelling/shrinking clay associated with volcanic failure. Identifying these zones provides crucial information in the production of a new lahar hazard map for the Tongariro National Park. The northern flank of the Te Maari craters was found to contain hydrothermal alteration products and this areas has generated many collapses in the past. Identifying large areas or mapping out larger zones of hydrothermal alteration products was not possible due to the small surface expression of some of the hydrothermal fields and also the atmospheric/signal to noise interference with the main satellite sensors. The mixed method approach used in this study remains useful and ongoing attempts at working with new hyperspectral data as it comes available should be investigated.
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    Late quarternary volcanic stratigraphy within a portion of the northeastern Tongariro volcanic centre : a thesis presented as partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science
    (Massey University, 1996) Cronin, Shane Jason
    Investigation of the Late Quaternary volcanic stratigraphy within the andesitic Tongariro Volcanic Centre has elucidated the history of construction of the northeastern Ruapehu and eastern Tongariro ring plains and provided a lahar record for the Tongariro catchment. Volcaniclastic ring-plain sequences were correlated and dated using rhyolitic and andesitic marker tephras. The identification of distal rhyolitic tephras in the area was improved by the application of discriminant function analysis (DFA) to their electron microprobe-determined glass chemistry. The Okaia. Omataroa and Hauparu Tephras and the Rotoehu Ash were identified for the first time in this area, providing a chronology for pre-22.6 ka ring-plain sequences not previously investigated. DFA of ferromagnesian mineral chemistry proved useful for discrimination of andesitic tephras. with titanomagnetite being the most useful phase. Development of an andesitic tephrostratigraphy in pre-22.6 ka sequences was aided by clustering analysis and DFA. Seven andesitic marker tephras were identified using a range of parameters to supplement the rhyolitic tephrostratigraphy. Using the tephrochronologic framework, 15 packages of lahar deposits were identified on the northeastern Ruapehu ring plain (from >64 to c. 5.2 ka) and six on the eastern Tongariro ring plain (from >22.6 to 11.9 ka). Lahar deposition on both ring plains was most voluminous and widespread during the last (Ohakean) and antepenultimate (Porewan) stadials of the last glacial (Otiran). Holocene lahars were restricted to a narrow sector of the northeastern Ruapehu ring plain. They appear to have been triggered mostly in response to large-scale tephra eruptions of Ruapehu and Tongariro, and mostly occurred along the path of the Mangatoetoenui Stream. Lahar deposits and surfaces beside the Tongariro River were mapped in eight lahar hazard zones, with lahar recurrence intervals ranging from 1 in >15 000 years to 1 in 35 years. The largest number and volume of lahars in this catchment occurred in the period from 14.7 to 10 ka. The greatest population risk identified in the Tongariro catchment is part of Turangi, built within a 1 in 1000 year lahar-hazard zone. Other property and infrastructure at greater risk include the State Highway 1 bridge across the Mangatoetoenui Stream and the Rangipo Dam and Power Station, within a 1 in 35 year hazard zone. The landscape of the northeastern Ruapehu and eastern Tongariro ring plains has developed in relation to late Quaternary climate changes in addition to volcanic activity. During the last and antepenultimate stadials of the last glacial, major ring-plain aggradation by lahars and streams occurred. This was probably in response to greater physical weathering and glacier action on the volcanic cones providing abundant sediment for lahars. During the warmer interstadials of the last glacial, soil development within andesitic ring plain material was greatest, particularly when the rate of soil accretion was low.