Vegetation dieback as a proxy for temperature within a wet pyroclastic density current: A novel experiment and observations from the 6th of August 2012 Tongariro eruption

The 6th of August 2012 eruption of Te Maari (Mt Tongariro, New Zealand) generated wet pyroclastic density currents (PDCs) which caused widespread dieback of vegetation (singed, brown foliage) in their path. An absence of significant charcoal formation suggests that PDC temperatures were mostly below 250 °C. Textural evidence for liquid water being present in the matrices during emplacement (vesicles) suggests that temperatures were b100 °C. We determined a probable minimum PDC temperature using an experiment replicating the critical temperatures required to induce foliar browning in seven species affected by the eruption. In locations where all species exhibited browned foliage (or were defoliated), temperatures were probably ≥64 °C assuming a PDC duration of 60 s. In the more distal areas, where only the most susceptible species were browned while others remained healthy and unaffected, temperatures were probably around 51–58 °C. These results have relevance to volcanic hazard mitigation and risk assessment, especially on the popular Tongariro Alpine Crossing

Mapping snow accumulation of Antarctica

Many regional studies have focused on snow accumulation in Antarctica but only a few have attempted to collate this data (Bromwich, 1988, Bromwich et al, 2004, Arthern 2006, Eisen et al 2008). In situ measurements of previous local studies within Antarctica are collated and interpolated onto a map with some comparison to Arthern’s 2006 mapping of snow accumulation base on ground-based and satellite measurements and passive microwave emission. Analysis of snow accumulation rates highlight the atmospheric, topographic, elevation, precipitation, wind distribution and sublimation are interacting and responsible for the results showing on a regional scale, focussing on Oates Land, Dronning Maud Land and the Filcher-Ronne Ice Shelf

The Relationship of the Maori with Antarctica - A Critical Review

Eldon Best (1923, p.27) describes Maori: "Their love of travel is innate; they are born sailors, and have invaded and conquered in many directions....are born Sailors and rovers - the sea is their home.” (Best, E. 1923) Best illustrates that Maori have a history of exploring and travelling. This review attempts to investigate Maori connections within Antarctica's history to establish where Maori youth pursuing Antarctic interests can connect and identify with. Due to knowledge being passed down by oral tradition within the Maori culture this review tries to consolidate what little literature may be available for future reference. It highlights common themes such as oppression, discrimination, biculturalism and whaling and as such a lot of the literature is a reflection of the times in which they were written and could have been an impediment on Maori involvement on relationships with the Antarctic. It also shows that when papers and books were written reference to New Zealand is always assumed to include Maori with no need to differentiate between ethnicities until it becomes a criminal issue in which case the dissociation is made certain. (Dodds & Yusoff, 2005., Dannette, 2010). Specific Maori are commented on for a key relationship played or either for commendable traits demonstrated in an effort to share with Maori today in the hope of increasing Maori involvement within New Zealand Antarctic society, and acknowledge the successes of Maori thus far. If anything it re-iterates what some already know and to educate what more should know as a part of New Zealand history, to get more Maorithinking about their concern for New Zealand's relationship with Antarctica

Geochronology and geochemical evolution of magma systems in the Taupō-Maroa area between two supereruptions: Whakamaru and Ōruanui

How volcanic systems behave between super eruptions is not well constrained yet is important in determining the factors that lead to supereruptions, such as how magma chambers evolve to supply caldera forming eruptions. This thesis investigates eruption products in the Taupō-Maroa area of the central Taupo Volcanic Zone (TVZ) to document the re-organisation of magma systems between two supereruptions: Whakamaru Group (349 ka) and Ōruanui (25.5 ka). A total of 220 samples of rhyolite lava, pumice and tephra were collected, 14 of those predate the Whakamaru Group. Major element, trace element and Sr isotopes were obtained on whole rock powders and used to distinguish magma types and source characteristics. Petrography and mineral compositions were used to identify the storage conditions of magma bodies. The geochemistry was tied to a geochronology framework using 40Ar/39Ar dates on plagioclase phenocrysts to understand magma system evolution.The oldest rocks investigated are lavas of the Western Dome Belt (WDB), subdivided into the Northwestern and Western dome complexes (NWDC + WDC) north and south, respectively, of the Waikato River. These lavas consistently yielded 40Ar/39Ar eruption ages of up to 100,000 years prior to the Whakamaru Group supereruption, indicating a long-lived geochemically distinct magmatic system existed before, and after, the supereruption. Domes are progressively younger from the NWDC to the northern shores of Lake Taupō whereas two domes south-west of Lake Taupo occurred immediately post-Whakamaru. Dome distributions are influenced by NW-SE regional and Taupō Fault Belt fault structures and a pre-Whakamaru N-S lineament related to the arc structural margin.In the pre-350 ka to pre-45 ka time-period sub-surface magma bodies supplying lava domes along the southern and northern shores of the current Lake Taupō and further north, were organised into six independent magma systems based on chronology, mineralogy, mineral chemistry and textures: 1) South-west shore domes 2) South-east shore domes, 3) NWDC + WDC 4) The Maroa dome complex, 5) the Northern shore domes, and 6) the NE dome system initiated at ~45 ka. The Northern shore domes evolved between ~50 to 100,000 years after the Maroa complex. These are discrete systems with one or more evolving into another (e.g., WDC evolving into Northern Shore indicated by shared plagioclase compositions, temperatures and pressures). Two amphibole types and two orthopyroxene populations suggest two different storage areas of magma towards the south-west. A deeper more mafic magma ascended and mixed with a shallow ponded magma beneath the South-west shore domes whereas incorporation of previous crystal mush material is present in the Northern shore domes. Shallow-forming amphibole and the bulk of plagioclase, orthopyroxene, and amphibole chemistry in NWDC and WDC lavas suggest that conditions that formed these phases were similar.Based on geochemistry, mineralogy, and Sr isotopes, 11 magma types were recognised on the surface. The spatial dispersal of magma types and mostly closed system Rb/Sr fractionation trends suggest eruption at different stages of magmatic differentiation. Barium, Rb and Sr illustrate three decreasing trends whilst Th, Ta, Nb, Zr highlight 3 parental source variations across 11 magma types. These three parental compositional variations have been generated through contrasting crustal domains via assimilation, from a single mantle source. Light rare earth element enrichment indicates different levels of crustal interaction or different crustal protoliths in each parental variation.87Sr/86Sr isotopic ratios revealed that two large-scale deeper crustal magma systems were operating in the area from ~450 ka to ~45 ka. The northern part of the study area is dominated by the lower isotopic signature, whilst the southern part is dominated by the more radiogenic signature. The Maroa lava domes are derived from a source with similar Sr-isotopic characteristics as the more evolved and older NWDC lava domes. In contrast, the WDC lavas are a mixture of at least three magma types, originating from two magma systems. The south-western lavas form a tight cluster from the higher 87Sr/86Sr magma system whilst the south-eastern domes are a separate magma system influenced by a more primitive basalt parent or different crustal source. The two deep crustal systems appear to have led geochemically and isotopically into two geologically recent magma systems on the northern lake margins (Ōruanui) and north-east of Lake Taupō. Hence, to a first order, the Ōruanui magma type, erupted from ~60-25.5 ka is descended from the higher 87Sr/86Sr system, whilst the modern NE dome magma system is the successor to the lower 87Sr/86Sr system. These findings collectively suggest four conclusions: 1) the typical behaviour of caldera volcanoes is of frequent small-volume eruptions rather than large-scale caldera forming eruptions, 2) the thermal flux changes spatially and temporally, 3) the fingerprint of the original crustal terrane that was assimilated by the parental magmas is preserved in the deposits, thus deposits on the surface can be correlated back to distinct parental magmas as depth and 4) substantial revision is required to models of the Whakamaru caldera structure.</p

Carbon emissions in Antarctica

In this report we consider (i) how National Programmes should respond to the challenge of reducing fuel consumption and carbon emissions and (ii) how National Programmes balance environmental values with other values associated with Antarctica. The rate of carbon emissions from activities undertaken in Antarctica, the impact of climate change in Antarctica and globally, and the role of the Antarctic in climate change science are all reasons why the reduction of carbon emissions should be important to National Programmes. National Programmes are obliged to follow the framework provided by the Antarctic Treaty System and COMNAP guidelines. However, analysis of the current practices of a sample of three National Programmes shows that their approach to reducing fuel consumption and carbon emissions is varied. In light of this, we recommend further initiatives that could be undertaken by National Programmes to enhance their efforts to reduce fuel consumption and carbon emissions. Any activity undertaken in Antarctica will have an environmental impact. In order to balance the conflict between environmental and other values National Programmes need to: Factor in the environmental impact of their activities; and Aim to minimise this impact

Mapping lithology and hydrothermal alteration in geothermal systems using portable X-ray fluorescence (pXRF): A case study from the Tauhara geothermal system, Taupo Volcanic Zone

Portable x-ray fluorescence (pXRF) analyzers are widely used in the environmental and mineral exploration fields. pXRF analyzers can rapidly and inexpensively provide chemical concentrations on a variety of elements, often with detection limits of ∼1–5 ppm. We compared portable XRF results from untreated geothermal drill cuttings with laboratory XRF results from pressed pellet and lithium borate fused beads prepared from powders crushed from the same samples. It is demonstrated that the portable XRF results are accurate for many elements, particularly for those with atomic numbers greater than 17. 304 cutting samples from three drillholes in the Tauhara geothermal field were subsequently analyzed by pXRF. Downhole elemental concentrations plotted against lithological units defined on geological well logs indicate that significant variations in elemental concentrations occur, some of which correlate with logged lithology boundaries. Other chemical variations appear to define previously unrecognized subunits, as well as areas of hydrothermal alteration. We suggest that pXRF should become a routine part of the characterization of geothermal cuttings during geothermal exploration and well drilling, as the chemical results are accurate, rapid and inexpensive, and the results can be used to define lithological boundaries and potentially correlate between drillholes, therefore improving geologic, stratigraphic and hydrothermal alteration models of the geothermal field

Seen but unheard: navigating turbulent waters as Māori and Pacific postgraduate students in STEM

The experiences of Māori and Pacific postgraduate students in STEM (Science, Technology, Engineering and Mathematics) offer insights into how universities, particularly science faculties, currently underserve Māori and Pacific people. This article shares the experiences of 43 current or past postgraduate students at New Zealand universities. Collectively, our stories offer insight into how representation, the white imprint, space invaders/stranger making, and institutional habits, specifically operate to exclude and devalue Māori and Pacific postgraduates in STEM. We provide new understandings of the white imprint (rewarding and incentivising white behaviour), where Māori and Pacific postgraduates were prevented from being their authentic selves. Importantly, this research documents how Māori and Pacific postgraduates experience excess labour because of institutional habits. This research also provides insight into how the science funding system results in superficial and unethical inclusion of Māori and Pacific postgraduates. Our stories provide persuasive evidence that the under-representation of Māori and Pacific in STEM will not be addressed by simply bolstering university enrolments. Instead, our stories highlight the urgent requirement for universities to change the STEM learning environment which continues to be violent and culturally unsafe for Māori and Pacific postgraduates.fals