title: TephraNZ: a major- and trace-element reference dataset for glass-shard analyses from prominent Quaternary rhyolitic tephras in New Zealand and implications for correlation

authors: Hopkins, Jenni L.

subjects: tephra

abstract: Although analyses of tephra-derived glass shards have been undertaken in New Zealand for nearly four decades (pioneered by Paul Froggatt), our study is the first to systematically develop a formal, comprehensive, openaccess reference dataset of glass-shard compositions for New Zealand tephras. These data will provide an important reference tool for future studies to identify and correlate tephra deposits and for associated petrological and magma-related studies within New Zealand and beyond. Here we present the foundation dataset for TephraNZ, an open-access reference dataset for selected tephra deposits in New Zealand. Prominent, rhyolitic, tephra deposits from the Quaternary were identified, with sample collection targeting original type sites or reference locations where the tephra’s identification is unequivocally known based on independent dating and/or mineralogical techniques. Glass shards were extracted from the tephra deposits, and major- and trace-element geochemical compositions were determined. We discuss in detail the data reduction process used to obtain the results and propose that future studies follow a similar protocol in order to gain comparable data. The dataset contains analyses of glass shards from 23 proximal and 27 distal tephra samples characterising 45 eruptive episodes ranging from Kaharoa (636 +- 12 cal yr BP) to the Hikuroa Pumice member (2.0 +- 0.6 Ma) from six or more caldera sources, most from the central Taupo Volcanic Zone. We report 1385 major element analyses obtained by electron microprobe (EMPA), and 590 trace-element analyses obtained by laser ablation (LA)-ICP-MS, on individual glass shards. Using principal component analysis (PCA), Euclidean similarity coefficients, and geochemical investigation, we show that chemical compositions of glass shards from individual eruptions are commonly distinguished by major elements, especially CaO, TiO2, K2O, and FeOtt (Na2+K2O and SiO2/K2O), but not always. For those tephras with similar glass major-element signatures, some can be distinguished using trace elements (e.g. HFSEs: Zr, Hf, Nb; LILE: Ba, Rb; REE: Eu, Tm, Dy, Y, Tb, Gd, Er, Ho, Yb, Sm) and trace-element ratios (e.g. LILE/HFSE: Ba/Th, Ba/Zr, Rb/Zr; HFSE/HREE: Zr/Y, Zr/Yb, Hf/Y; LREE/HREE: La/Yb, Ce/Yb). Geochemistry alone cannot be used to distinguish between glass shards from the following tephra groups: Taupo (Unit Y in the post-Oruanui eruption sequence of Taupo¯ volcano) and Waimihia (Unit S); Poronui (Unit C) and Karapiti (Unit B); Rotorua and Rerewhakaaitu; and Kawakawa/Oruanui, and Okaia. Other characteristics, including stratigraphic relationships and age, can be used to separate and distinguish all of these otherwise-similar tephra deposits except Poronui and Karapiti. Bimodality caused by K2O variability is newly identified in Poihipi and Tahuna tephras. Using glass-shard compositions, tephra sourced from Taupo Volcanic Centre (TVC) and Mangakino Volcanic Centre (MgVC) can be separated using bivariate plots of SiO2+K2O vs. Na2O/K2O. Glass shards from tephras derived from Kapenga Volcanic Centre, Rotorua Volcanic Centre, and Whakamaru Volcanic Centre have similar major- and trace-element chemical compositions to those from the MgVC, but they can overlap with glass analyses from tephras from Taupo and Okataina volcanic centres. Specific trace elements and trace-element ratios have lower variability than the heterogeneous majorelement and bimodal signatures, making them easier to fingerprint geochemically.

text: TephraNZ: a major- and trace-element reference dataset for glass-shard analyses from prominent Quaternary rhyolitic tephras in New Zealand and implications for correlation Although analyses of tephra-derived glass shards have been undertaken in New Zealand for nearly four decades (pioneered by Paul Froggatt), our study is the first to systematically develop a formal, comprehensive, openaccess reference dataset of glass-shard compositions for New Zealand tephras. These data will provide an important reference tool for future studies to identify and correlate tephra deposits and for associated petrological and magma-related studies within New Zealand and beyond. Here we present the foundation dataset for TephraNZ, an open-access reference dataset for selected tephra deposits in New Zealand. Prominent, rhyolitic, tephra deposits from the Quaternary were identified, with sample collection targeting original type sites or reference locations where the tephra’s identification is unequivocally known based on independent dating and/or mineralogical techniques. Glass shards were extracted from the tephra deposits, and major- and trace-element geochemical compositions were determined. We discuss in detail the data reduction process used to obtain the results and propose that future studies follow a similar protocol in order to gain comparable data. The dataset contains analyses of glass shards from 23 proximal and 27 distal tephra samples characterising 45 eruptive episodes ranging from Kaharoa (636 +- 12 cal yr BP) to the Hikuroa Pumice member (2.0 +- 0.6 Ma) from six or more caldera sources, most from the central Taupo Volcanic Zone. We report 1385 major element analyses obtained by electron microprobe (EMPA), and 590 trace-element analyses obtained by laser ablation (LA)-ICP-MS, on individual glass shards. Using principal component analysis (PCA), Euclidean similarity coefficients, and geochemical investigation, we show that chemical compositions of glass shards from individual eruptions are commonly distinguished by major elements, especially CaO, TiO2, K2O, and FeOtt (Na2+K2O and SiO2/K2O), but not always. For those tephras with similar glass major-element signatures, some can be distinguished using trace elements (e.g. HFSEs: Zr, Hf, Nb; LILE: Ba, Rb; REE: Eu, Tm, Dy, Y, Tb, Gd, Er, Ho, Yb, Sm) and trace-element ratios (e.g. LILE/HFSE: Ba/Th, Ba/Zr, Rb/Zr; HFSE/HREE: Zr/Y, Zr/Yb, Hf/Y; LREE/HREE: La/Yb, Ce/Yb). Geochemistry alone cannot be used to distinguish between glass shards from the following tephra groups: Taupo (Unit Y in the post-Oruanui eruption sequence of Taupo¯ volcano) and Waimihia (Unit S); Poronui (Unit C) and Karapiti (Unit B); Rotorua and Rerewhakaaitu; and Kawakawa/Oruanui, and Okaia. Other characteristics, including stratigraphic relationships and age, can be used to separate and distinguish all of these otherwise-similar tephra deposits except Poronui and Karapiti. Bimodality caused by K2O variability is newly identified in Poihipi and Tahuna tephras. Using glass-shard compositions, tephra sourced from Taupo Volcanic Centre (TVC) and Mangakino Volcanic Centre (MgVC) can be separated using bivariate plots of SiO2+K2O vs. Na2O/K2O. Glass shards from tephras derived from Kapenga Volcanic Centre, Rotorua Volcanic Centre, and Whakamaru Volcanic Centre have similar major- and trace-element chemical compositions to those from the MgVC, but they can overlap with glass analyses from tephras from Taupo and Okataina volcanic centres. Specific trace elements and trace-element ratios have lower variability than the heterogeneous majorelement and bimodal signatures, making them easier to fingerprint geochemically.

year: 2021

title: Editorial: Entrepreneurship research: follow the yellow-brick road?

authors: Corner, Patricia

subjects: entrepreneurship

abstract: If entrepreneurship theory, research, and practice represent Oz at the culmination of the yellow-brick road, Dorothy and her companions have much company on their journey. For example, one source estimates that 460 million people worldwide either start a new business or become the owners of new businesses annually (Reynolds et al. 2002). Moreover, entrepreneurship is the fastest growing field of study in tertiary education in North America and Europe (Bygrave 2004) and fifteen specialized scholarly journals disseminate research on the topic globally. Within the policy-making arena, the governments of both Australia and New Zealand seek to promote entrepreneurship as an engine of economic growth. This special issue on entrepreneurship thus appears to be timely and can help to take stock of this topic within our Australasian context. It can also serve as a baseline from which to consider directions for future research in this important area of inquiry.

text: Editorial: Entrepreneurship research: follow the yellow-brick road? If entrepreneurship theory, research, and practice represent Oz at the culmination of the yellow-brick road, Dorothy and her companions have much company on their journey. For example, one source estimates that 460 million people worldwide either start a new business or become the owners of new businesses annually (Reynolds et al. 2002). Moreover, entrepreneurship is the fastest growing field of study in tertiary education in North America and Europe (Bygrave 2004) and fifteen specialized scholarly journals disseminate research on the topic globally. Within the policy-making arena, the governments of both Australia and New Zealand seek to promote entrepreneurship as an engine of economic growth. This special issue on entrepreneurship thus appears to be timely and can help to take stock of this topic within our Australasian context. It can also serve as a baseline from which to consider directions for future research in this important area of inquiry.

year: 2007

title: One hundred years of Sylvia Ashton-Warner: An introduction.

authors: Middleton, Sue

subjects: Sylvia Ashton-Warner

abstract: A biography of Sylvia Ashton-Warner is presented. She was born on 17 December 1908 in New Zealand. She studied at the Auckland Teachers' Training College and taught in several native schools including Horoera Native School and Pipiriki Native School. Later she started writing, starting with "Teacher," a book about teaching schemes and followed by "Incense to Idols," "Bell Call," and "Greenstone." Also, her travels to various places are mentioned.

text: One hundred years of Sylvia Ashton-Warner: An introduction. A biography of Sylvia Ashton-Warner is presented. She was born on 17 December 1908 in New Zealand. She studied at the Auckland Teachers' Training College and taught in several native schools including Horoera Native School and Pipiriki Native School. Later she started writing, starting with "Teacher," a book about teaching schemes and followed by "Incense to Idols," "Bell Call," and "Greenstone." Also, her travels to various places are mentioned.

year: 2008