title: Morphology and geochemistry of glauconite from the Te Kuiti Group, South Auckland region, New Zealand

authors: Compton, Martyn Stephen

abstract: The late Eocene - Oligocene Te Kuiti Group comprises calcareous mudstone, calcareous sandstone and skeletal or sandy limestone formed in marginal marine to fully marine shelf settings. Glauconite is ubiquitous in all sedimentary units in low concentration (5-10%), but at unconformities or near formation boundaries can attain concentrations > 75%.
Binocular microscope studies show· the following morphological form abundances: ovoidal(40-55%) > fragmentary(20-40%) > lobate(5-15%) > casts (0-5%) with trace quantities of tabular, capsule, and vermicular grains. The abundance of ovoidal and fragmentary glauconite suggests the glauconite is dominantly allogenic. Only the highly fragile cast and lobate grains are considered reliable indicators of authigenic glauconite.
Because distinction of morphological types using the binocular microscope is subjective, an alternative classification based on measured variables using image analysis was attempted. Seven measurements (area, formfactor, convexicity, length, fractal, aspect, and fibre) were made for each grain image. Seven glauconite morphological types were investigated: capsule, cauliflower, fragmentary, lobate, ovoidal, tabular, and vermicular. Measurement data were analysed using canonical variate analysis. The calculated discriminating vectors were then used to distinguish the seven morpological forms. Using two canonical variates 81.5% of the variability within the database was accounted for.
X-ray diffraction studies shows a predominance of poorly crystalline glauconite. Many difficulties were encountered when applying previous literature techniques for calculating the expandable content of glauconite. An alternative technique based on the relationship between %K₂0 and % expandables is favoured for the calculation of % expandables. A relationship between host sediment lithology and glauconite expandable content was found; siltstone = 20-32%. expandables in the glauconite, sandstone = 8-15% expandables in the glauconite.
Major element data were obtained with the electron microprobe for 327 individual glauconite grain centres of 70 samples from 45 sites and 7 formations in the Te Kuiti. Group. The. chemical data were analysed using canonical variate analysis and the seven formations were clearly distinguished. Because only a small glauconite sample size is required (4-5 grains) the technique has potential for determining the stratigraphic correlation of drill core samples and small hand specimens of Te Kuiti Group material containing glauconite.
The range composition of Te Kuiti Group glauconite calculated from EMP major element data using the "Clayform" program is:
(Si ₃.₄₀₋₃.₆₈ Al ₀.₃₂₋₀.₆₀) (Al ₀.₀₈₋₀.₄₁ Fe ₁.₀₀³⁺₋₁.₃₆ Fe ₀.₁₉²⁺₋₀.₂₆ Mg ₀.₄₀₋₀.₆₀) (Ca ₀.₀₂₋₀.₁₆ Na ₀.₀₀₋₀.₀₄ K₀.₄₉₋₀.₆₇) O₁₀(OH₂)
The Te Kuiti Group passes stratigraphically upward from terrigenous and mixed terrigenous-skeletal carbonate deposits to very pure limestones. Early post-depositional diagenetic processes probably released Mg from the carbonate lattice of accumulating skeletal grains. Some of the released Mg was incorporated into the glauconite lattice as evidenced by the increase in Mg content of glauconite stratigraphically upward, parallel with the increased carbonate content of the rocks.
Major and trace element data were obtained using X-ray fluorescence for 29 bulk glauconite concentrates from 21 sites and 5 formations. Notably there were anomalous Mg, Pb and Ni concentrations in glauconite from the Otorohanga - Waitomo -Te Kuiti area. This suggests the area existed as a small semi-enclosed embayment, with a significantly higher terrigenous input compared with adjacent depocentres.
A strong correlation between the La/Ce ratio of glauconite and paleontological and oxygen isotope-derived sea-water temperatures suggests glauconite La/Ce ratio may be a useful paleotemperature indicator. The data collected in this study show no single previously suggested process adequately decribes the development of glauconite. Rather, glauconite should be considered polygenetic.

text: Morphology and geochemistry of glauconite from the Te Kuiti Group, South Auckland region, New Zealand The late Eocene - Oligocene Te Kuiti Group comprises calcareous mudstone, calcareous sandstone and skeletal or sandy limestone formed in marginal marine to fully marine shelf settings. Glauconite is ubiquitous in all sedimentary units in low concentration (5-10%), but at unconformities or near formation boundaries can attain concentrations > 75%.
Binocular microscope studies show· the following morphological form abundances: ovoidal(40-55%) > fragmentary(20-40%) > lobate(5-15%) > casts (0-5%) with trace quantities of tabular, capsule, and vermicular grains. The abundance of ovoidal and fragmentary glauconite suggests the glauconite is dominantly allogenic. Only the highly fragile cast and lobate grains are considered reliable indicators of authigenic glauconite.
Because distinction of morphological types using the binocular microscope is subjective, an alternative classification based on measured variables using image analysis was attempted. Seven measurements (area, formfactor, convexicity, length, fractal, aspect, and fibre) were made for each grain image. Seven glauconite morphological types were investigated: capsule, cauliflower, fragmentary, lobate, ovoidal, tabular, and vermicular. Measurement data were analysed using canonical variate analysis. The calculated discriminating vectors were then used to distinguish the seven morpological forms. Using two canonical variates 81.5% of the variability within the database was accounted for.
X-ray diffraction studies shows a predominance of poorly crystalline glauconite. Many difficulties were encountered when applying previous literature techniques for calculating the expandable content of glauconite. An alternative technique based on the relationship between %K₂0 and % expandables is favoured for the calculation of % expandables. A relationship between host sediment lithology and glauconite expandable content was found; siltstone = 20-32%. expandables in the glauconite, sandstone = 8-15% expandables in the glauconite.
Major element data were obtained with the electron microprobe for 327 individual glauconite grain centres of 70 samples from 45 sites and 7 formations in the Te Kuiti. Group. The. chemical data were analysed using canonical variate analysis and the seven formations were clearly distinguished. Because only a small glauconite sample size is required (4-5 grains) the technique has potential for determining the stratigraphic correlation of drill core samples and small hand specimens of Te Kuiti Group material containing glauconite.
The range composition of Te Kuiti Group glauconite calculated from EMP major element data using the "Clayform" program is:
(Si ₃.₄₀₋₃.₆₈ Al ₀.₃₂₋₀.₆₀) (Al ₀.₀₈₋₀.₄₁ Fe ₁.₀₀³⁺₋₁.₃₆ Fe ₀.₁₉²⁺₋₀.₂₆ Mg ₀.₄₀₋₀.₆₀) (Ca ₀.₀₂₋₀.₁₆ Na ₀.₀₀₋₀.₀₄ K₀.₄₉₋₀.₆₇) O₁₀(OH₂)
The Te Kuiti Group passes stratigraphically upward from terrigenous and mixed terrigenous-skeletal carbonate deposits to very pure limestones. Early post-depositional diagenetic processes probably released Mg from the carbonate lattice of accumulating skeletal grains. Some of the released Mg was incorporated into the glauconite lattice as evidenced by the increase in Mg content of glauconite stratigraphically upward, parallel with the increased carbonate content of the rocks.
Major and trace element data were obtained using X-ray fluorescence for 29 bulk glauconite concentrates from 21 sites and 5 formations. Notably there were anomalous Mg, Pb and Ni concentrations in glauconite from the Otorohanga - Waitomo -Te Kuiti area. This suggests the area existed as a small semi-enclosed embayment, with a significantly higher terrigenous input compared with adjacent depocentres.
A strong correlation between the La/Ce ratio of glauconite and paleontological and oxygen isotope-derived sea-water temperatures suggests glauconite La/Ce ratio may be a useful paleotemperature indicator. The data collected in this study show no single previously suggested process adequately decribes the development of glauconite. Rather, glauconite should be considered polygenetic.

year: 1989

title: Editorial: Composition in the English/literacy classroom

authors: Locke, Terry

subjects: writing

abstract: The act of writing is a complex task. About that, there is almost complete agreement, whether you are a psychologist, a linguist, a socio-cultural theorist, a teacher, or a student battling with an assignment deadline and a blank page. For the emergent writer in the infant classroom, the challenge of communicating in writing is compounded by the sheer effort of transcription – remembering to put spaces between words, shaping upper and lower case letters, marking sentence boundaries with full stops, and representing words in your head as accurately spelled sequences of letters on the page. For the older writer, the complexity persists, though the challenges change. Although transcribing text onto paper or screen may be less effortful, understanding the expectations of the writing task and imagining the needs of the (implied) reader create different obstacles to effortless composition.

text: Editorial: Composition in the English/literacy classroom The act of writing is a complex task. About that, there is almost complete agreement, whether you are a psychologist, a linguist, a socio-cultural theorist, a teacher, or a student battling with an assignment deadline and a blank page. For the emergent writer in the infant classroom, the challenge of communicating in writing is compounded by the sheer effort of transcription – remembering to put spaces between words, shaping upper and lower case letters, marking sentence boundaries with full stops, and representing words in your head as accurately spelled sequences of letters on the page. For the older writer, the complexity persists, though the challenges change. Although transcribing text onto paper or screen may be less effortful, understanding the expectations of the writing task and imagining the needs of the (implied) reader create different obstacles to effortless composition.

year: 2007

title: Place attachment of Ngāi Te Ahi to Hairini Marae

authors: Teddy, Lani

subjects: Hairini

abstract: Twelve members of Ngāi Te Ahi, a hapū from Tauranga, were interviewed to explore how they talk about their place attachment to Hairini Marae.  This was organized around five key dimensions of place attachment taken from the literature—continuity, distinctiveness, symbolism, attachment and familiarity.  We found that in discussing all dimensions, place attachment was equally about social and cultural relationships, history, and socialization.  Place attachment for groups such as Māori is complex because it encompasses all social relationships past and present.  The implication for those working with Māori is to take seriously the wider connotations of place when talking to Māori about marae, traditional homelands, and their land.

text: Place attachment of Ngāi Te Ahi to Hairini Marae Twelve members of Ngāi Te Ahi, a hapū from Tauranga, were interviewed to explore how they talk about their place attachment to Hairini Marae.  This was organized around five key dimensions of place attachment taken from the literature—continuity, distinctiveness, symbolism, attachment and familiarity.  We found that in discussing all dimensions, place attachment was equally about social and cultural relationships, history, and socialization.  Place attachment for groups such as Māori is complex because it encompasses all social relationships past and present.  The implication for those working with Māori is to take seriously the wider connotations of place when talking to Māori about marae, traditional homelands, and their land.

year: 2008