title: A micromorphological study of pedogenic processes in an evolutionary soil sequence formed on Late Quaternary rhyolitic tephra deposits, North Island, New Zealand

authors: Bakker, L.

abstract: The influence of time as a soil forming factor was studied on an evolutionary sequence of five soils (1850 radiocarbo years BP-ca. 120,000 BP) developed in rhyolitic tephra deposits in New Zealand. New micromorphological observations were combined with existing macromorphological, chemical, textural, and clay mineralogical analyses to assess the extent of polygenesis in the soils. The younger soils (1850 BP to ca. 22,600 BP) are characterised by initial weathering and little secondary mineral formation. This status is expressed by abundant pumice fragments and fresh, easily weatherable minerals, as well as a low clay content with an isotropic character. Comminution and neoformation are the main pedological processes. The older soils (ca. 120,000 BP) are characterised by a high degree of alteration of primary minerals, little or no pumice fragments, clay illuviation, gleying, and a high clay content (>80%) consisting of a range of crystalline clay minerals including halloysite, gibbsite, kaolinite, and vermiculite, plus crystalline iron oxides. Evidence of polygenesis can be observed in the micromorphology of the older soils: (1) the range of secondary minerals is the result of the integration and succession of soil-forming processes through time; (2) the accumulatory character of the tephra deposits has resulted in stronger weathering of the lower horizons than upper horizons because of continuous pedogenesis. Such polygenesis in the older soils supports the view that the older the soil, the more polygenetic it is likely to be.

text: A micromorphological study of pedogenic processes in an evolutionary soil sequence formed on Late Quaternary rhyolitic tephra deposits, North Island, New Zealand The influence of time as a soil forming factor was studied on an evolutionary sequence of five soils (1850 radiocarbo years BP-ca. 120,000 BP) developed in rhyolitic tephra deposits in New Zealand. New micromorphological observations were combined with existing macromorphological, chemical, textural, and clay mineralogical analyses to assess the extent of polygenesis in the soils. The younger soils (1850 BP to ca. 22,600 BP) are characterised by initial weathering and little secondary mineral formation. This status is expressed by abundant pumice fragments and fresh, easily weatherable minerals, as well as a low clay content with an isotropic character. Comminution and neoformation are the main pedological processes. The older soils (ca. 120,000 BP) are characterised by a high degree of alteration of primary minerals, little or no pumice fragments, clay illuviation, gleying, and a high clay content (>80%) consisting of a range of crystalline clay minerals including halloysite, gibbsite, kaolinite, and vermiculite, plus crystalline iron oxides. Evidence of polygenesis can be observed in the micromorphology of the older soils: (1) the range of secondary minerals is the result of the integration and succession of soil-forming processes through time; (2) the accumulatory character of the tephra deposits has resulted in stronger weathering of the lower horizons than upper horizons because of continuous pedogenesis. Such polygenesis in the older soils supports the view that the older the soil, the more polygenetic it is likely to be.

year: 1996

title: Volcanic Geology of Maungatautari: An Andesitic-Dacitic Composite Cone, Central Waikato, New Zealand

authors: Prentice, Marlena Lee

abstract: Maungatautari is an extinct andesitic-dacitic composite cone volcano, situated 35 km southeast of Hamilton, that rises prominently in the Waikato region. A single radiometric age of 1.8 Ma, indicates volcanic activity here was contemporaneous with subduction-related volcanism of the nearby Alexandra Volcanics and the early Taupo Volcanic Zone. The geology and volcanism of Maungatautari was previously addressed (1950s-80s) in context of the broader volcanic geology of the Waikato region, however, only a single dedicated volcanic study, undertaken over 30 years ago, provided insight into the chemical composition and origin of the magmas. This study applied modern volcanological techniques and concepts to reconstruct the volcanic history of Maungatautari and how it may relate to volcanism elsewhere in the Waikato Region around 2 Ma. The work incorporates field and desktop geomorphic analysis, volcanic stratigraphy and facies analysis, petrographic and mineralogical studies, and elemental and isotopic geochemical analysis.
Maungatautari overlies Jurassic Manaia Hill group rocks of the Waipapa Terrane and abuts a range of the same rocks immediately to the west. It is surrounded to the north, east and south by a thick ignimbrite plateau which overlies the lowermost flanks of the mountain, originating from the Mangakino caldera to the southeast. Catastrophic failure of the northeastern flank produced a 0.28 km3 rock avalanche deposit over an area of approximately 1.6 km2. The deposits of rock falls, slides and debris flows were also commonly observed and demonstrate that numerous mass-wasting processes have continued to occur into the present.
Lavas at Maungatautari consist of non-vesicular labradorite, pyroxene and hornblende andesites and hornblende dacites along with olivine basalt at the small cone at Kairangi 7 km to the northwest. Whole rock geochemical and strontium and neodymium analyses demonstrate these lavas were derived from at least three distinct mantle-melt sources: the fractionation of subduction-related, deep, garnet-bearing, depleted mantle (most andesites and dacites); a shallower, garnet-free, upper mantle (low SiO2 hornblende andesites) and an area of deeper enriched mantle (Kairangi olivine basalt). This study considers Maungatautari to reflect andesitic volcanism occurring along the edge of the continental tip of the Colville volcanic arc c. 2 Ma with the near-by Alexandra Volcanics being contemporaneous, behind-arc subduction-related volcanoes. The olivine basalt at Kairangi is more reflective of intraplate over subduction-related melts and is unrelated to magmatism at Maungatautari.
This study is the first to document a record of explosive volcanism at Maungatautari. Eruption styles which occurred at Maungatautari include the effusion of lava resulting in the generation of lava flows and domes, and vulcanian to sub-plinian explosive eruptions which produced both high and low particle concentration pyroclastic density currents.

text: Volcanic Geology of Maungatautari: An Andesitic-Dacitic Composite Cone, Central Waikato, New Zealand Maungatautari is an extinct andesitic-dacitic composite cone volcano, situated 35 km southeast of Hamilton, that rises prominently in the Waikato region. A single radiometric age of 1.8 Ma, indicates volcanic activity here was contemporaneous with subduction-related volcanism of the nearby Alexandra Volcanics and the early Taupo Volcanic Zone. The geology and volcanism of Maungatautari was previously addressed (1950s-80s) in context of the broader volcanic geology of the Waikato region, however, only a single dedicated volcanic study, undertaken over 30 years ago, provided insight into the chemical composition and origin of the magmas. This study applied modern volcanological techniques and concepts to reconstruct the volcanic history of Maungatautari and how it may relate to volcanism elsewhere in the Waikato Region around 2 Ma. The work incorporates field and desktop geomorphic analysis, volcanic stratigraphy and facies analysis, petrographic and mineralogical studies, and elemental and isotopic geochemical analysis.
Maungatautari overlies Jurassic Manaia Hill group rocks of the Waipapa Terrane and abuts a range of the same rocks immediately to the west. It is surrounded to the north, east and south by a thick ignimbrite plateau which overlies the lowermost flanks of the mountain, originating from the Mangakino caldera to the southeast. Catastrophic failure of the northeastern flank produced a 0.28 km3 rock avalanche deposit over an area of approximately 1.6 km2. The deposits of rock falls, slides and debris flows were also commonly observed and demonstrate that numerous mass-wasting processes have continued to occur into the present.
Lavas at Maungatautari consist of non-vesicular labradorite, pyroxene and hornblende andesites and hornblende dacites along with olivine basalt at the small cone at Kairangi 7 km to the northwest. Whole rock geochemical and strontium and neodymium analyses demonstrate these lavas were derived from at least three distinct mantle-melt sources: the fractionation of subduction-related, deep, garnet-bearing, depleted mantle (most andesites and dacites); a shallower, garnet-free, upper mantle (low SiO2 hornblende andesites) and an area of deeper enriched mantle (Kairangi olivine basalt). This study considers Maungatautari to reflect andesitic volcanism occurring along the edge of the continental tip of the Colville volcanic arc c. 2 Ma with the near-by Alexandra Volcanics being contemporaneous, behind-arc subduction-related volcanoes. The olivine basalt at Kairangi is more reflective of intraplate over subduction-related melts and is unrelated to magmatism at Maungatautari.
This study is the first to document a record of explosive volcanism at Maungatautari. Eruption styles which occurred at Maungatautari include the effusion of lava resulting in the generation of lava flows and domes, and vulcanian to sub-plinian explosive eruptions which produced both high and low particle concentration pyroclastic density currents.

year: 2017

title: 1999 Professorial Address: Nau te rourou, naku te rourou… Māori education: setting an agenda.

authors: Bishop, Russell

subjects: educational outcomes

abstract: Current educational policies and practices in Aotearoa/New Zealand were developed and continue to be developed within a framework of power imbalances, which effects Maori the greatest. An alternative model that seeks to address indigenous Māori aspirations and Treaty of Waitangi guarantees for self determination is presented here. This model suggests how a tertiary teacher education institution might create learning contexts wherein power-sharing images, principles and practices will facilitate successful participation by Māori students in mainstream classrooms. This model constitutes the classroom as a place where young people's sense-making processes (cultures) are incorporated and enhanced, where the existing knowledges of young people are seen as "acceptable" and "official" and where the teacher interacts with students in such a way that new knowledge is co-created. Such a classroom will generate totally different interaction and participation patterns and educational outcomes from a classroom where knowledge is seen as something that the teacher makes sense of and then passes on to students.

text: 1999 Professorial Address: Nau te rourou, naku te rourou… Māori education: setting an agenda. Current educational policies and practices in Aotearoa/New Zealand were developed and continue to be developed within a framework of power imbalances, which effects Maori the greatest. An alternative model that seeks to address indigenous Māori aspirations and Treaty of Waitangi guarantees for self determination is presented here. This model suggests how a tertiary teacher education institution might create learning contexts wherein power-sharing images, principles and practices will facilitate successful participation by Māori students in mainstream classrooms. This model constitutes the classroom as a place where young people's sense-making processes (cultures) are incorporated and enhanced, where the existing knowledges of young people are seen as "acceptable" and "official" and where the teacher interacts with students in such a way that new knowledge is co-created. Such a classroom will generate totally different interaction and participation patterns and educational outcomes from a classroom where knowledge is seen as something that the teacher makes sense of and then passes on to students.

year: 2000