title: Initial sedimentation processes and the  early geological evolution of three maar craters,  Hindon Maar Complex, Otago

authors: Murphy, Caitlin Emily Joy

subjects: sedimentation,

abstract: The Hindon Maar Complex, located near Hindon, 25 km NW of Dunedin, consists of four volcanic craters infilled by lake sediments and mass flow deposits. The maars form part of the Waipiata volcanic group, which was active from 25–9 Ma. Drilling of Maar 1, Maar 3 and a sediment-filled depression between the inferred locations of Maar 2 and Maar 3 revealed up to 10 m of laminated biogenic lake sediments underlain by siliciclastic mass flow deposits. This project describes the siliciclastic deposits from these drill-cores and from limited outcrops of Maar 2. Physical properties, stratigraphic logs, X-ray fluorescence spectrometry, Also XRD, SEM and optical petrography are used to create a facies analysis and infer the processes of initial sedimentation into the maar craters following the maar-forming eruptions. 
A total of 10 facies are identified within the Hindon Maar complex. Facies 1–6 show the progression of crater wall stabilisation from rockfalls which occurred weeks to years after the initial eruption to the formation of organic rich lake-sediment units which would have been deposited hundreds of years post eruption. Facies 1–6 have a high proportion of mica, quartz and schist grains, indicating extensive incorporation of the country rock. Nonconsolidated mottles are found throughout facies 2–5 and are interpreted as the remnants of weathered pyroclastic materials which were sourced from failures in the upper crater walls or tephra ring. 
Facies 1 is a laminated carbonaceous lake sediment consisting almost entirely of organic matter. Facies 2 is a nonconsolidated laminated silty clay formed by debris flows. Facies 3 is a consolidated silty fine sand with discrete gravel lenses and 5% mottles formed as a result of mass flows. Facies 4 is a fine gravel breccia comprising up to 35% mottles, which is formed by mass flows originating in the upper crater or tephra ring. Facies 5 is a poorly consolidated fine gravel breccia which formed as a result of turbidity currents. Facies 6 is loose schist and quartz grains of fine gravel to medium pebble size, formed by rockfalls into the early lake. 
Facies 7 is a silty clay which is geochemically and mineralogically different to all other facies. Facies 7 exhibits convoluted bedding and is an example of a slump deposit occurring locally in Maar 3. Due to its significant differences to all other facies, it is assumed to have had a different parent material.
Facies 8–10 are found in the area of a major gravity anomaly associated with Maar 3. These deposits are composed of silt and clay sized particles and have elevated Fe. They have high magnetic susceptibility and density and are interpreted as weathered pyroclastic material of the tephra ring.
The infilling of Maar 1 occurred initially as a series of coarse-grained mass flows into the crater (Facies 6 and Facies 5). Once the crater wall began to stabilise and the occurrence of rockfalls decreased, Facies 4 was deposited, resulting from high crater wall collapse. This was followed by furthered, small cater wall collapse of Facies 3. Facies 2 was later deposited once crater wall failures halted, and resulted from the erosion, rather than the collapse, of the crater wall. Once the crater wall was fully vegetated, Facies 1 began to accumulate, forming thick organic rich deposits, indicating the maar lake was stratified and had an anoxic bottom layer.
The infilling of Maar 3 followed the same pattern. However, there is a significant lateral offset between some units of the same facies, which may indicate more complex processes, such as faulting. The exact history of Maar 3 cannot be determined with the information acquired.

text: Initial sedimentation processes and the  early geological evolution of three maar craters,  Hindon Maar Complex, Otago The Hindon Maar Complex, located near Hindon, 25 km NW of Dunedin, consists of four volcanic craters infilled by lake sediments and mass flow deposits. The maars form part of the Waipiata volcanic group, which was active from 25–9 Ma. Drilling of Maar 1, Maar 3 and a sediment-filled depression between the inferred locations of Maar 2 and Maar 3 revealed up to 10 m of laminated biogenic lake sediments underlain by siliciclastic mass flow deposits. This project describes the siliciclastic deposits from these drill-cores and from limited outcrops of Maar 2. Physical properties, stratigraphic logs, X-ray fluorescence spectrometry, Also XRD, SEM and optical petrography are used to create a facies analysis and infer the processes of initial sedimentation into the maar craters following the maar-forming eruptions. 
A total of 10 facies are identified within the Hindon Maar complex. Facies 1–6 show the progression of crater wall stabilisation from rockfalls which occurred weeks to years after the initial eruption to the formation of organic rich lake-sediment units which would have been deposited hundreds of years post eruption. Facies 1–6 have a high proportion of mica, quartz and schist grains, indicating extensive incorporation of the country rock. Nonconsolidated mottles are found throughout facies 2–5 and are interpreted as the remnants of weathered pyroclastic materials which were sourced from failures in the upper crater walls or tephra ring. 
Facies 1 is a laminated carbonaceous lake sediment consisting almost entirely of organic matter. Facies 2 is a nonconsolidated laminated silty clay formed by debris flows. Facies 3 is a consolidated silty fine sand with discrete gravel lenses and 5% mottles formed as a result of mass flows. Facies 4 is a fine gravel breccia comprising up to 35% mottles, which is formed by mass flows originating in the upper crater or tephra ring. Facies 5 is a poorly consolidated fine gravel breccia which formed as a result of turbidity currents. Facies 6 is loose schist and quartz grains of fine gravel to medium pebble size, formed by rockfalls into the early lake. 
Facies 7 is a silty clay which is geochemically and mineralogically different to all other facies. Facies 7 exhibits convoluted bedding and is an example of a slump deposit occurring locally in Maar 3. Due to its significant differences to all other facies, it is assumed to have had a different parent material.
Facies 8–10 are found in the area of a major gravity anomaly associated with Maar 3. These deposits are composed of silt and clay sized particles and have elevated Fe. They have high magnetic susceptibility and density and are interpreted as weathered pyroclastic material of the tephra ring.
The infilling of Maar 1 occurred initially as a series of coarse-grained mass flows into the crater (Facies 6 and Facies 5). Once the crater wall began to stabilise and the occurrence of rockfalls decreased, Facies 4 was deposited, resulting from high crater wall collapse. This was followed by furthered, small cater wall collapse of Facies 3. Facies 2 was later deposited once crater wall failures halted, and resulted from the erosion, rather than the collapse, of the crater wall. Once the crater wall was fully vegetated, Facies 1 began to accumulate, forming thick organic rich deposits, indicating the maar lake was stratified and had an anoxic bottom layer.
The infilling of Maar 3 followed the same pattern. However, there is a significant lateral offset between some units of the same facies, which may indicate more complex processes, such as faulting. The exact history of Maar 3 cannot be determined with the information acquired.

year: 2018

title: The dynamics of ¹³C in several New Zealand lakes

authors: McCabe, Bruce

abstract: The main objectives of this study were to;
(i) Determine how the 𝜹¹³C of autochthonous production in fresh water lakes varies with productivity and trophic state.
(ii) Determine if such variations can be used for the investigation of lake palaeoenvironment.
(iii) Quantify the effect of anthropogenic activity on the productivity of Hamilton Basin lakes.
The viability of this project was assessed by monitoring the dissolved inorganic carbon chemistry of an eutrophic pond during a period of high insolation and algal productivity. These observations revealed that during the day, the Pc0₂ in the euphotic zone was reduced to levels low enough to affect. photosynthetic carbon isotopic fractionation, and hence plankton 𝜹¹³C values. The enrichment of ¹³C in the dissolved inorganic carbon (DIC) pool during periods of high
photosynthetic productivity also affects plankton 𝜹¹³C values. Analysis of diurnal changes in 𝜹¹³C and DIC concentration using the Rayleigh equation suggested that photosynthetic fractionation factors changed in response to changes in ambient P𝒸ₒ₂  levels.
The effect of lake trophic state on phytoplankton photosynthetic carbon isotopic fractionation was further investigated using closed system batch cultures of zooplankton-free natural algal populations collected from lakes of differing trophic state. The results indicated
that;
(i) There are considerable differences between algal communities, photosynthetic production and apparent CO₂  compensation points for cultures of algae from lakes of differing trophic state.
(ii) Plankton from a eutrophic lake were able to photosynthesise down to a low and had a variable photosynthetic carbon isotopic fractionation factor, (ep), which varied as a function of the P𝒸ₒ₂ .
(iii) Plankton from a mesotrophic lake were unable to reduce the Pc0₂   below 300ppm and exhibited a constant ∈p .
(iv) Carbon dioxide availability could be limiting plankton photosynthesis in productive eutrophic lakes, and may result in HCO₃⁻ use.
Phytoplankton 𝜹¹³C values and photosynthetic fractionation factors have the potential to be used to detect changes in plankton productivity and substrate use.
A study was made of the isotopic chemistry of the DIC and particulate organic matter, (POM), in six Hamilton Basin lakes with trophic states ranging from hypertrophic to oligotrophic-mesotrophic and dystrophic. From this study, it was concluded that;
(i) The isotopic chemistry of the DIC is a function of:
- catchment composition
- the relative amounts and 𝜹¹³C of inorganic carbon supplied from the atmosphere and biogenic sources.
- the mixing regime of the lake.
(ii) 𝜹¹³Cₚₒₘ varies seasonally in concert with changes in algal biomass.
(iii) Because variations in 𝜹¹³Cₚₒₘ result primarily from changes in the photosynthetic fractionation factor, ∆¹³C₍ₚₒₘ₋𝒸ₒ₂₍ₐq₎₎they can be used to detect changes in the productivity of lakes.
(i v) 𝜹¹³Cₚₒₘ values could not be used to rank lakes in order of increasing productivity because of the effect of systematic differences in the 𝜹¹³C 𝒸ₒ₂₍ₐq₎of different lakes.
(v) POM produced in the euphotic zone is incorporated in the sediment with only a small (-1%) change in its 𝜹¹³C, thus enabling sediment 𝜹¹³C values to be used to source organic carbon in the sediment and to investigate lake palaeoproductivity.
Large systematic variations were observed in sediment 𝜹¹³C values during the development of lakes. By assuming that the 𝜹¹³C 𝒸ₒ₂₍ₐq₎ had remained constant during lake development, an attempt was made to determine the palaeoenvironment of these lakes from sediment 𝜹¹³C values. It was concluded that the productivity of these lakes had undergone considerable changes during their development in response to climatically and anthropologically induced changes in the catchment vegetation. Low forest cover results in high or increased lake productivity, whilst dense forest cover led to low or reduced lake productivity. Lakes formed in the late glacial times had a high productivity, (low forest cover and high nutrient loading), which reduced as the forest cover developed. Peat development also affected some of the lakes.
An attempt was made to assess the effect of anthropogenic activity in the Hamilton Basin on the metabolism of the lakes from changes in the recent sediment 𝜹¹³C values and a comparison of present day 𝜹¹³Cₚₒₘ values with recent sediment 𝜹¹³C values. The results indicate that;
(i) Anthropogenic activity had a marked affect on lake metabolism, resulting in increased terrigenous inputs and/or increased productivity. This was particularly evident in Lake Hakanoa, where deforestation of the area by early Polynesian settlers resulted in a large increase in lake productivity.
(ii) Several of the lakes have very recently undergone a marked increase in their productivity, a result of European activity in the area. 
Thus, plankton productivity has a systematic affect on the 𝜹¹³C of the POM incorporated in lake sediments, which has the potential to be used in the investigation of lake palaeoproductivity, and in assessing the effect of anthropogenic activity on lake productivity.

text: The dynamics of ¹³C in several New Zealand lakes The main objectives of this study were to;
(i) Determine how the 𝜹¹³C of autochthonous production in fresh water lakes varies with productivity and trophic state.
(ii) Determine if such variations can be used for the investigation of lake palaeoenvironment.
(iii) Quantify the effect of anthropogenic activity on the productivity of Hamilton Basin lakes.
The viability of this project was assessed by monitoring the dissolved inorganic carbon chemistry of an eutrophic pond during a period of high insolation and algal productivity. These observations revealed that during the day, the Pc0₂ in the euphotic zone was reduced to levels low enough to affect. photosynthetic carbon isotopic fractionation, and hence plankton 𝜹¹³C values. The enrichment of ¹³C in the dissolved inorganic carbon (DIC) pool during periods of high
photosynthetic productivity also affects plankton 𝜹¹³C values. Analysis of diurnal changes in 𝜹¹³C and DIC concentration using the Rayleigh equation suggested that photosynthetic fractionation factors changed in response to changes in ambient P𝒸ₒ₂  levels.
The effect of lake trophic state on phytoplankton photosynthetic carbon isotopic fractionation was further investigated using closed system batch cultures of zooplankton-free natural algal populations collected from lakes of differing trophic state. The results indicated
that;
(i) There are considerable differences between algal communities, photosynthetic production and apparent CO₂  compensation points for cultures of algae from lakes of differing trophic state.
(ii) Plankton from a eutrophic lake were able to photosynthesise down to a low and had a variable photosynthetic carbon isotopic fractionation factor, (ep), which varied as a function of the P𝒸ₒ₂ .
(iii) Plankton from a mesotrophic lake were unable to reduce the Pc0₂   below 300ppm and exhibited a constant ∈p .
(iv) Carbon dioxide availability could be limiting plankton photosynthesis in productive eutrophic lakes, and may result in HCO₃⁻ use.
Phytoplankton 𝜹¹³C values and photosynthetic fractionation factors have the potential to be used to detect changes in plankton productivity and substrate use.
A study was made of the isotopic chemistry of the DIC and particulate organic matter, (POM), in six Hamilton Basin lakes with trophic states ranging from hypertrophic to oligotrophic-mesotrophic and dystrophic. From this study, it was concluded that;
(i) The isotopic chemistry of the DIC is a function of:
- catchment composition
- the relative amounts and 𝜹¹³C of inorganic carbon supplied from the atmosphere and biogenic sources.
- the mixing regime of the lake.
(ii) 𝜹¹³Cₚₒₘ varies seasonally in concert with changes in algal biomass.
(iii) Because variations in 𝜹¹³Cₚₒₘ result primarily from changes in the photosynthetic fractionation factor, ∆¹³C₍ₚₒₘ₋𝒸ₒ₂₍ₐq₎₎they can be used to detect changes in the productivity of lakes.
(i v) 𝜹¹³Cₚₒₘ values could not be used to rank lakes in order of increasing productivity because of the effect of systematic differences in the 𝜹¹³C 𝒸ₒ₂₍ₐq₎of different lakes.
(v) POM produced in the euphotic zone is incorporated in the sediment with only a small (-1%) change in its 𝜹¹³C, thus enabling sediment 𝜹¹³C values to be used to source organic carbon in the sediment and to investigate lake palaeoproductivity.
Large systematic variations were observed in sediment 𝜹¹³C values during the development of lakes. By assuming that the 𝜹¹³C 𝒸ₒ₂₍ₐq₎ had remained constant during lake development, an attempt was made to determine the palaeoenvironment of these lakes from sediment 𝜹¹³C values. It was concluded that the productivity of these lakes had undergone considerable changes during their development in response to climatically and anthropologically induced changes in the catchment vegetation. Low forest cover results in high or increased lake productivity, whilst dense forest cover led to low or reduced lake productivity. Lakes formed in the late glacial times had a high productivity, (low forest cover and high nutrient loading), which reduced as the forest cover developed. Peat development also affected some of the lakes.
An attempt was made to assess the effect of anthropogenic activity in the Hamilton Basin on the metabolism of the lakes from changes in the recent sediment 𝜹¹³C values and a comparison of present day 𝜹¹³Cₚₒₘ values with recent sediment 𝜹¹³C values. The results indicate that;
(i) Anthropogenic activity had a marked affect on lake metabolism, resulting in increased terrigenous inputs and/or increased productivity. This was particularly evident in Lake Hakanoa, where deforestation of the area by early Polynesian settlers resulted in a large increase in lake productivity.
(ii) Several of the lakes have very recently undergone a marked increase in their productivity, a result of European activity in the area. 
Thus, plankton productivity has a systematic affect on the 𝜹¹³C of the POM incorporated in lake sediments, which has the potential to be used in the investigation of lake palaeoproductivity, and in assessing the effect of anthropogenic activity on lake productivity.

year: 1985

title: Māori & Psychology Research Unit Annual Report 2012

authors: Waitoki, Waikaremoana

abstract: Annual report of the Māori and Psychology Research Unit (MPRU) 2012. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

text: Māori & Psychology Research Unit Annual Report 2012 Annual report of the Māori and Psychology Research Unit (MPRU) 2012. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

year: 2012