title: Geology, History and Stratigraphy of Hydrothermal Eruptions in the Rotorua Geothermal Field

authors: Cody, Ashley Douglas

subjects: Geothermal Hydrothermal eruptions Rotorua

abstract: The study area is the Rotorua geothermal field (RGF), which is located in the southern end of the Rotorua caldera. Distribution of surface geothermal activity, hydrothermal eruption (HE) deposits and craters have been mapped. HE deposits formed in geological, historical and modern times were studied to record and describe their distribution, composition, petrography, lithology and stratigraphy.

Locations of all identified HE sites in the RGF have been plotted and shown on accompanying maps. At Ohinemutu and Sulphur Bay, HE breccias have been preserved only where deposits were subsequently silicified by hot spring outflows. At Whakarewarewa two HE breccias outcrop over about 0.5 km² and are up to 23 m thick. Study of stratigraphic relationships with tephras of known ages has determined one as Holocene (c. 20 ka) and one of Late Pleistocene age (c. 65 ka).

Four HE breccias were studied in detail. The mineral composition, physical description, field characteristics and spatial distribution of HE breccias are described and mapped. Clasts and matrix were examined by XRD analyses of whole (67) and clay fraction separates (16). Silica crystallinity indices (14) were determined by XRD to identify devitrification rates of opaline mineral species. The petrography of 67 breccia clasts and matrix samples were studied, and polished sections showed the only sulphide to be pyrite. Geothermal alteration of all prehistorical HE deposits was of advanced argillic to argillic and one modern day deposit was of sub propylitic epithermal alteration.

Study of a HE deposit formed in Kuirau Park on 26 January 2001 allowed properties and mineral composition to be examined and recorded before rapid oxidation and weathering destroyed its physical and mineral composition. Study of this and other twentieth century HE events confirms that these rapidly decompose to leave little or no recognisable deposit in the geological record.

Descriptions and all known historical records of HEs in the RGF have been collated to provide a comprehensive inventory of maps and appendices of these events. This information will greatly assist statutory authorities with mitigation of risk to lives and property from geothermal hazards as well as aid appropriate land use and emergency services planning.

Hydrothermal eruptions are ongoing in the RGF through time and produce craters 2 - 110m diameter with erupted deposit volumes of 1 - 500,000 m³ that have distributed over <5 m² to >0.5 km². These have occurred throughout at least Late Pleistocene to Holocene times and appear to have been triggered by such events as volcanic eruptions from the adjacent Okataina Volcanic Centre and related abrupt changes to the waterlevels of Lake Rotorua. Frequency and spatial distribution of HEs in historical times suggest human interference with the geothermal system is also a significant influence.

This study has brought together all records of known hydrothermal eruptions and other unusual geothermal disturbances in the Rotorua geothermal field. The information has plotted into GIS for use by statutory authorities and others. Two prehistorical HE deposits in Rotorua city have also been recognised and described for the first time, together with identification of their likely vent locations and possible eruption initiating events.

text: Geology, History and Stratigraphy of Hydrothermal Eruptions in the Rotorua Geothermal Field The study area is the Rotorua geothermal field (RGF), which is located in the southern end of the Rotorua caldera. Distribution of surface geothermal activity, hydrothermal eruption (HE) deposits and craters have been mapped. HE deposits formed in geological, historical and modern times were studied to record and describe their distribution, composition, petrography, lithology and stratigraphy.

Locations of all identified HE sites in the RGF have been plotted and shown on accompanying maps. At Ohinemutu and Sulphur Bay, HE breccias have been preserved only where deposits were subsequently silicified by hot spring outflows. At Whakarewarewa two HE breccias outcrop over about 0.5 km² and are up to 23 m thick. Study of stratigraphic relationships with tephras of known ages has determined one as Holocene (c. 20 ka) and one of Late Pleistocene age (c. 65 ka).

Four HE breccias were studied in detail. The mineral composition, physical description, field characteristics and spatial distribution of HE breccias are described and mapped. Clasts and matrix were examined by XRD analyses of whole (67) and clay fraction separates (16). Silica crystallinity indices (14) were determined by XRD to identify devitrification rates of opaline mineral species. The petrography of 67 breccia clasts and matrix samples were studied, and polished sections showed the only sulphide to be pyrite. Geothermal alteration of all prehistorical HE deposits was of advanced argillic to argillic and one modern day deposit was of sub propylitic epithermal alteration.

Study of a HE deposit formed in Kuirau Park on 26 January 2001 allowed properties and mineral composition to be examined and recorded before rapid oxidation and weathering destroyed its physical and mineral composition. Study of this and other twentieth century HE events confirms that these rapidly decompose to leave little or no recognisable deposit in the geological record.

Descriptions and all known historical records of HEs in the RGF have been collated to provide a comprehensive inventory of maps and appendices of these events. This information will greatly assist statutory authorities with mitigation of risk to lives and property from geothermal hazards as well as aid appropriate land use and emergency services planning.

Hydrothermal eruptions are ongoing in the RGF through time and produce craters 2 - 110m diameter with erupted deposit volumes of 1 - 500,000 m³ that have distributed over <5 m² to >0.5 km². These have occurred throughout at least Late Pleistocene to Holocene times and appear to have been triggered by such events as volcanic eruptions from the adjacent Okataina Volcanic Centre and related abrupt changes to the waterlevels of Lake Rotorua. Frequency and spatial distribution of HEs in historical times suggest human interference with the geothermal system is also a significant influence.

This study has brought together all records of known hydrothermal eruptions and other unusual geothermal disturbances in the Rotorua geothermal field. The information has plotted into GIS for use by statutory authorities and others. Two prehistorical HE deposits in Rotorua city have also been recognised and described for the first time, together with identification of their likely vent locations and possible eruption initiating events.

year: 2003

title: Collaborative Partnerships: An Investigation of Co-construction in Secondary Classrooms

authors: Mansell, Heather Lorraine

subjects: co-construction

abstract: The understanding that learning develops best in participatory, collaborative, interactive partnerships suggests that attempts to establish such relationships in classrooms deserve scrutiny. This study investigates co-constructive approaches to teaching and learning in a New Zealand secondary school. It studies co-construction from the perspectives of seven mathematics teachers and one art teacher and their students, as the teachers attempted to co-construct aspects of the classroom curriculum with students.

This study focused on the practices, understandings and expectations of both teachers and students when co-constructing. In addition, it identified the potential constraints and difficulties that impacted on such practices in this secondary setting. Ideally, such classrooms demonstrate collaborative, democratic, socially just practices with sharing of power between teacher and student: ideas emanating from theorists such as Dewey, Bruner, Freire and Vygotsky. This interpretive study responds to the dearth of research in New Zealand secondary classrooms about such approaches. It draws on principles and methods of grounded theory (Charmaz, 2003, 2006) to analyse the rich data generated by multiple methods. This allows the meanings of participants to prevail, by guarding against the imposition of meanings from either literature or researcher. Methods of data collection included classroom observation, interviews with teachers and groups of students, audiorecording and various forms of documentation sourced from these.

The findings showed co-constructive practice has shared characteristics, such as spontaneity, quality teacher-student communication with a stress on the teacher as a listener, active participation by learners, and a distinction of varying qualities of practice. However, classrooms are not formulaic, as each teacher evolves their own approach. Initially, strong subject pedagogical traditions and mythologies emerged as barriers to co-construction, particularly in mathematics. Learning is involved for all participants in pedagogical change. Students generally responded positively as co-construction provided opportunities for some input, choice and control of their learning which improved relevance, motivation and responsibility. While very aware of the issues related to the use of particular strategies such as groups, the positives of helping each other learn prevailed. 

The numerous potential constraints to easy implementation of co-construction reflected the diversity of teacher and student personal traits and beliefs about pedagogy, roles, and responsibilities. Moreover, teacher subject and pedagogical knowledge had import, as did their need to establish control and a relationship of trust with a class. The difficulty of secondary settings was endorsed. However, despite these, aspirational reasons for continuing to co-construct were expressed in the benefits experienced by both teachers and students.

This study demonstrates how co-construction features in the daily interactions which comprise the classroom curriculum, even where there are constraints to formal consultation over content of classroom programmes. If the bi-directionality of classroom interactions is acknowledged, students have spaces for influence, input and control. It affirms the importance and the diversity of perspective that both teachers and learners bring to the partnership. The need to persevere to establish and grow this approach in secondary schools is strongly advocated. This approach maximises respectful relationships, dialogue, innovation, and excitement in teaching and learning.

text: Collaborative Partnerships: An Investigation of Co-construction in Secondary Classrooms The understanding that learning develops best in participatory, collaborative, interactive partnerships suggests that attempts to establish such relationships in classrooms deserve scrutiny. This study investigates co-constructive approaches to teaching and learning in a New Zealand secondary school. It studies co-construction from the perspectives of seven mathematics teachers and one art teacher and their students, as the teachers attempted to co-construct aspects of the classroom curriculum with students.

This study focused on the practices, understandings and expectations of both teachers and students when co-constructing. In addition, it identified the potential constraints and difficulties that impacted on such practices in this secondary setting. Ideally, such classrooms demonstrate collaborative, democratic, socially just practices with sharing of power between teacher and student: ideas emanating from theorists such as Dewey, Bruner, Freire and Vygotsky. This interpretive study responds to the dearth of research in New Zealand secondary classrooms about such approaches. It draws on principles and methods of grounded theory (Charmaz, 2003, 2006) to analyse the rich data generated by multiple methods. This allows the meanings of participants to prevail, by guarding against the imposition of meanings from either literature or researcher. Methods of data collection included classroom observation, interviews with teachers and groups of students, audiorecording and various forms of documentation sourced from these.

The findings showed co-constructive practice has shared characteristics, such as spontaneity, quality teacher-student communication with a stress on the teacher as a listener, active participation by learners, and a distinction of varying qualities of practice. However, classrooms are not formulaic, as each teacher evolves their own approach. Initially, strong subject pedagogical traditions and mythologies emerged as barriers to co-construction, particularly in mathematics. Learning is involved for all participants in pedagogical change. Students generally responded positively as co-construction provided opportunities for some input, choice and control of their learning which improved relevance, motivation and responsibility. While very aware of the issues related to the use of particular strategies such as groups, the positives of helping each other learn prevailed. 

The numerous potential constraints to easy implementation of co-construction reflected the diversity of teacher and student personal traits and beliefs about pedagogy, roles, and responsibilities. Moreover, teacher subject and pedagogical knowledge had import, as did their need to establish control and a relationship of trust with a class. The difficulty of secondary settings was endorsed. However, despite these, aspirational reasons for continuing to co-construct were expressed in the benefits experienced by both teachers and students.

This study demonstrates how co-construction features in the daily interactions which comprise the classroom curriculum, even where there are constraints to formal consultation over content of classroom programmes. If the bi-directionality of classroom interactions is acknowledged, students have spaces for influence, input and control. It affirms the importance and the diversity of perspective that both teachers and learners bring to the partnership. The need to persevere to establish and grow this approach in secondary schools is strongly advocated. This approach maximises respectful relationships, dialogue, innovation, and excitement in teaching and learning.

year: 2009

title: Te karanga tūturu o maieke:  Ngāti Kuri women’s taiao geographies

authors: Ringham, Sandra Lee

subjects: Māori and Indigenous geographies

abstract: This research examines the relationships, identities and sense of belonging of Māori women of within the Ngāti Kuri iwi (tribe) and te taiao (the natural world, environment, nature, country) in Te Hiku o te Ika, Far North, Aotearoa New Zealand. It shows how Ngāti Kuri women and te taiao are embedded in - yet also resist - colonial and patriarchal discourses. 
The Kaupapa Māori and Mana Wahine theoretical framework decolonises and transforms the ways in which Māori women have been represented and marginalised. Pūrākau (storywork) as a theory and methodology ensures Ngāti Kuri women’s stories are told by them and for them. Indigenous relational geography is woven into the theoretical framework to further understand Indigenous relationships to place and diverse feelings of belonging and responsibility.
Whakawhiti kōrero (research conversations), wānanga (workshops) and tipi haere (mobile wānanga) were carried out with 19 Ngāti Kuri women. Approximately 40 people from the iwi and / or scientific communities contribute to the thesis through the initiatives of the Ngāti Kuri Relationship Working Group (NKRWG), the Auckland War Memorial Museum and other research partners and as conservationists. 
Findings are organised around three themes: identities; relationships; and a sense of belonging. The first theme introduces Ngāti Kuri women’s identities as leaders and drivers of change, disrupting and dismantling the intersection of patriarchal and colonial discourse. The pūrākau of Maieke, a founding ancestress of Ngāti Kuri, brings to light the reclamation and transformation of Māori women’s identities and geographies, as defined by participants. Pre-colonisation Ngāti Kuri women had the capacity and authority to become a governing force in the daily lives of the iwi. The second theme highlights colonial and patriarchal naming of our world. Ngāti Kuri women are reconfiguring relationships and representation through the scientific naming of taonga (culturally valuable objects and species). Values and principles of kaitiakitanga (inherited guardianship) and whakawhanaugatanga (relating well to others) guide the naming process. The third theme focuses on participants’ reflections and understandings of the ways in which they sense place and feelings of belonging. Participants’ engagement with te taiao - through singing, storying and sensing place – highlights the way te taiao re-centres and transforms Ngāti Kuri women’s relationships and experiences of belonging to iwi homelands.
Importantly, the thesis concludes with a discussion of the challenges, successes and actions of Ngāti Kuri women as they continue to strive for tino rangatiratanga (self-determination), social and environmental well-being. I conceptualise new geographies that account for, and celebrate, uniquely Ngāti Kuri understandings of identities, relationships and feelings of belonging. Finally, a short creative story ends the thesis in order to show the transformative power of Ngāti Kuri women’s te taiao experiences.

text: Te karanga tūturu o maieke:  Ngāti Kuri women’s taiao geographies This research examines the relationships, identities and sense of belonging of Māori women of within the Ngāti Kuri iwi (tribe) and te taiao (the natural world, environment, nature, country) in Te Hiku o te Ika, Far North, Aotearoa New Zealand. It shows how Ngāti Kuri women and te taiao are embedded in - yet also resist - colonial and patriarchal discourses. 
The Kaupapa Māori and Mana Wahine theoretical framework decolonises and transforms the ways in which Māori women have been represented and marginalised. Pūrākau (storywork) as a theory and methodology ensures Ngāti Kuri women’s stories are told by them and for them. Indigenous relational geography is woven into the theoretical framework to further understand Indigenous relationships to place and diverse feelings of belonging and responsibility.
Whakawhiti kōrero (research conversations), wānanga (workshops) and tipi haere (mobile wānanga) were carried out with 19 Ngāti Kuri women. Approximately 40 people from the iwi and / or scientific communities contribute to the thesis through the initiatives of the Ngāti Kuri Relationship Working Group (NKRWG), the Auckland War Memorial Museum and other research partners and as conservationists. 
Findings are organised around three themes: identities; relationships; and a sense of belonging. The first theme introduces Ngāti Kuri women’s identities as leaders and drivers of change, disrupting and dismantling the intersection of patriarchal and colonial discourse. The pūrākau of Maieke, a founding ancestress of Ngāti Kuri, brings to light the reclamation and transformation of Māori women’s identities and geographies, as defined by participants. Pre-colonisation Ngāti Kuri women had the capacity and authority to become a governing force in the daily lives of the iwi. The second theme highlights colonial and patriarchal naming of our world. Ngāti Kuri women are reconfiguring relationships and representation through the scientific naming of taonga (culturally valuable objects and species). Values and principles of kaitiakitanga (inherited guardianship) and whakawhanaugatanga (relating well to others) guide the naming process. The third theme focuses on participants’ reflections and understandings of the ways in which they sense place and feelings of belonging. Participants’ engagement with te taiao - through singing, storying and sensing place – highlights the way te taiao re-centres and transforms Ngāti Kuri women’s relationships and experiences of belonging to iwi homelands.
Importantly, the thesis concludes with a discussion of the challenges, successes and actions of Ngāti Kuri women as they continue to strive for tino rangatiratanga (self-determination), social and environmental well-being. I conceptualise new geographies that account for, and celebrate, uniquely Ngāti Kuri understandings of identities, relationships and feelings of belonging. Finally, a short creative story ends the thesis in order to show the transformative power of Ngāti Kuri women’s te taiao experiences.

year: 2022