title: Subsurface stratigraphy and petrology of a cool-water carbonate fracture reservoir - the mid-tertiary Tikorangi Formation, Taranaki Basin, New Zealand

authors: Hood, Steven D.

abstract: The totally subsurface Oligocene-Early Miocene Tikorangi Formation in Taranaki Basin is New Zealand’s only commercially-producing fractured-carbonate reservoir, but is poorly understood in a stratigraphic-sedimentological-diagenetic context. Based on correlation between laboratory and geophysical well log data a carbonate facies-based lithostratigraphy has been established for the first time for the entire formation. Petrogenesis of this complex siliciclastic-carbonate-dominated sequence, (re)deposited as a mix of retrogradational, progradational, and aggradational sedimentary sequences across a range of shallow-shelfal, foredeep and basinal settings, has been controlled by proximity to a rapidly evolving convergent Australian-Pacific plate boundary, to changes in relative sea level within an overall transgressive regime, to foredeep trough accommodation, to location within a cool-water temperate latitude setting, and to the changing availability and sources of carbonate and siliciclastic supply. 

The history and nature of burial diagenesis have been instrumental in the creation and subsequent modification of fracture porosity within the Tikorangi Formation by producing a tight, low porosity/permeability rock; burial replacive dolomitisation with no associated secondary porosity development; intense fracturing, thrusting, and folding in association with compression at the Australian-Pacific plate boundary; and precipitation of a complex suite of ferroan calcite, baroque dolomite, celestite, and quartzine minerals within fracture systems. Petrographic, trace element, stable isotope (δ¹⁸O and δ¹³C), and fluid inclusion data record a complex history of changing pore fluid chemistry and heating during burial, punctuated by relative changes in the input of downward circulating meteoric and upwelling basinal fluids. Precursory hydrocarbon-bearing fluids from Eocene terrestrial source rocks have migrated along with aqueous fluids after about 8 Ma, with major hydrocarbon emplacement within the fracture systems since the Early Pliocene. 

The Tikorangi Formation’s mixed siliciclastic-carbonate nature, heterozoan biotic carbonate make-up, low-Mg calcite mineralogy of skeletons and cements, and delayed deep burial diagenetic history are key features of current cool-water carbonate models. However, these evolving models of temperate carbonate sedimentation generally remain to incorporate several features exemplified by the Tikorangi Formation deposits, including: the recognition of a full spectrum of shelf-slope-basin facies and not simply shallow platform carbonates; the importance of mass emplacement events in producing complex mixed shelfal and deeper water skeletal assemblages; the textural diversity of deposits in which mudstones, wackestones and packstones are more common than grainstones; the ubiquitous occurrence of late diagenetic dolomite in the deposits; and the fact that cool-water carbonate facies can form economically important fracture reservoir rocks. While this study has provided new insights into the subsurface stratigraphy, petrology and diagenesis of the cool-water Tikorangi Formation carbonate fracture reservoir, an important research focus for the future is to further our understanding of temperate carbonate-dominated depositional and diagenetic systems as a whole, thereby enabling more concise assessment of their potential economic significance.

text: Subsurface stratigraphy and petrology of a cool-water carbonate fracture reservoir - the mid-tertiary Tikorangi Formation, Taranaki Basin, New Zealand The totally subsurface Oligocene-Early Miocene Tikorangi Formation in Taranaki Basin is New Zealand’s only commercially-producing fractured-carbonate reservoir, but is poorly understood in a stratigraphic-sedimentological-diagenetic context. Based on correlation between laboratory and geophysical well log data a carbonate facies-based lithostratigraphy has been established for the first time for the entire formation. Petrogenesis of this complex siliciclastic-carbonate-dominated sequence, (re)deposited as a mix of retrogradational, progradational, and aggradational sedimentary sequences across a range of shallow-shelfal, foredeep and basinal settings, has been controlled by proximity to a rapidly evolving convergent Australian-Pacific plate boundary, to changes in relative sea level within an overall transgressive regime, to foredeep trough accommodation, to location within a cool-water temperate latitude setting, and to the changing availability and sources of carbonate and siliciclastic supply. 

The history and nature of burial diagenesis have been instrumental in the creation and subsequent modification of fracture porosity within the Tikorangi Formation by producing a tight, low porosity/permeability rock; burial replacive dolomitisation with no associated secondary porosity development; intense fracturing, thrusting, and folding in association with compression at the Australian-Pacific plate boundary; and precipitation of a complex suite of ferroan calcite, baroque dolomite, celestite, and quartzine minerals within fracture systems. Petrographic, trace element, stable isotope (δ¹⁸O and δ¹³C), and fluid inclusion data record a complex history of changing pore fluid chemistry and heating during burial, punctuated by relative changes in the input of downward circulating meteoric and upwelling basinal fluids. Precursory hydrocarbon-bearing fluids from Eocene terrestrial source rocks have migrated along with aqueous fluids after about 8 Ma, with major hydrocarbon emplacement within the fracture systems since the Early Pliocene. 

The Tikorangi Formation’s mixed siliciclastic-carbonate nature, heterozoan biotic carbonate make-up, low-Mg calcite mineralogy of skeletons and cements, and delayed deep burial diagenetic history are key features of current cool-water carbonate models. However, these evolving models of temperate carbonate sedimentation generally remain to incorporate several features exemplified by the Tikorangi Formation deposits, including: the recognition of a full spectrum of shelf-slope-basin facies and not simply shallow platform carbonates; the importance of mass emplacement events in producing complex mixed shelfal and deeper water skeletal assemblages; the textural diversity of deposits in which mudstones, wackestones and packstones are more common than grainstones; the ubiquitous occurrence of late diagenetic dolomite in the deposits; and the fact that cool-water carbonate facies can form economically important fracture reservoir rocks. While this study has provided new insights into the subsurface stratigraphy, petrology and diagenesis of the cool-water Tikorangi Formation carbonate fracture reservoir, an important research focus for the future is to further our understanding of temperate carbonate-dominated depositional and diagenetic systems as a whole, thereby enabling more concise assessment of their potential economic significance.

year: 2000

title: The inflection point hypothesis: The relationship between the temperature dependence of enzyme-catalyzed reaction rates and microbial growth rates.

authors: Prentice, Erica J.

subjects: Peptides and proteins

abstract: The temperature dependence of biological rates at different scales (from individual enzymes to isolated organisms to ecosystem processes such as soil respiration and photosynthesis) is the subject of much historical and contemporary research. The precise relationship between the temperature dependence of enzyme rates and those at larger scales is not well understood. We have developed macromolecular rate theory (MMRT) to describe the temperature dependence of biological processes at all scales. Here we formalize the scaling relationship by investigating MMRT both at the molecular scale (constituent enzymes) and for growth of the parent organism. We demonstrate that the inflection point (𝘛ᵢₙ𝒻) for the temperature dependence of individual metabolic enzymes coincides with the optimal growth temperature for the parent organism, and we rationalize this concordance in terms of the necessity for linearly correlated rates for metabolic enzymes over fluctuating environmental temperatures to maintain homeostasis. Indeed, 𝘛ᵢₙ𝒻 is likely to be under strong selection pressure to maintain coordinated rates across environmental temperature ranges. At temperatures at which rates become uncorrelated, we postulate a regulatory catastrophe and organism growth rates precipitously decline at temperatures where this occurs. We show that the curvature in the plots of the natural log of the rate versus temperature for individual enzymes determines the curvature for the metabolic process overall and the curvature for the temperature dependence of the growth of the organism. We have called this "the inflection point hypothesis", and this hypothesis suggests many avenues for future investigation, including avenues for engineering the thermal tolerance of organisms.

text: The inflection point hypothesis: The relationship between the temperature dependence of enzyme-catalyzed reaction rates and microbial growth rates. The temperature dependence of biological rates at different scales (from individual enzymes to isolated organisms to ecosystem processes such as soil respiration and photosynthesis) is the subject of much historical and contemporary research. The precise relationship between the temperature dependence of enzyme rates and those at larger scales is not well understood. We have developed macromolecular rate theory (MMRT) to describe the temperature dependence of biological processes at all scales. Here we formalize the scaling relationship by investigating MMRT both at the molecular scale (constituent enzymes) and for growth of the parent organism. We demonstrate that the inflection point (𝘛ᵢₙ𝒻) for the temperature dependence of individual metabolic enzymes coincides with the optimal growth temperature for the parent organism, and we rationalize this concordance in terms of the necessity for linearly correlated rates for metabolic enzymes over fluctuating environmental temperatures to maintain homeostasis. Indeed, 𝘛ᵢₙ𝒻 is likely to be under strong selection pressure to maintain coordinated rates across environmental temperature ranges. At temperatures at which rates become uncorrelated, we postulate a regulatory catastrophe and organism growth rates precipitously decline at temperatures where this occurs. We show that the curvature in the plots of the natural log of the rate versus temperature for individual enzymes determines the curvature for the metabolic process overall and the curvature for the temperature dependence of the growth of the organism. We have called this "the inflection point hypothesis", and this hypothesis suggests many avenues for future investigation, including avenues for engineering the thermal tolerance of organisms.

year: 2020

title: Maori at Te Aroha after the opening of the goldfield in 1880 (mostly through Pakeha eyes)

authors: Hart, Philip

abstract: As the Maori population continued to decline, the aged rangatira admired by Pakeha (even including those who had fought against the Crown) gradually died off, to be replaced by Maori more noted for their drinking and occasional violence than their prestige. Although concerts and haka were popular with many Pakeha, much Maori behaviour was mocked, including by children. Many Maori were seen as being unsophisticated, unable to express themselves properly in English, and prone to drunkenness and laziness, whereas those who adopted Pakeha ways were praised.
Some Pakeha sympathized with poverty-stricken Maori and regretted the decline of their language. There were many examples of close and friendly relations and of Maori assisting Pakeha in trouble, but in general they lived geographically separate lives. To earn money, Maori were forced to work at road making, timber cutting, gum digging, and farming what land remained in their possession. Most Maori struggled financially, their limited resources being stretched by holding expensive tangi and entertaining visitors – resulting in more land sales. They used the court system to defend their economic interests.
Ngati Rahiri (including supporters of the Kingitanga) were seen as ‘loyal’ to the Crown, and visiting Maori kings received kindly treatment from Pakeha as well as from Maori. 
Poor health prompted some government assistance, but poor housing remained, although some attempts were made to improve it (partly to protect Pakeha from diseases). Before the twentieth century only a few children, mostly ‘half-castes’, were educated. Most Ngati Rahiri were members of the Church of England before being attracted by the new Mormon faith.
Ngati Rahiri participated with Pakeha in horse races, sporting contests, and, especially, rugby, and a few joined the Volunteers. Much less desirable to most residents was their heavy drinking (encouraged by some publicans and their Pakeha drinking buddies), and occasional fights, very occasionally with Pakeha. Overall, Pakeha ways, both good and bad, of necessity were adopted, and Ngati Rahiri became inextricably a subordinate part of the Pakeha community, although still retaining some distinctive features. 

 (Note: Unless otherwise indicated, all those named in this paper, both Maori and Pakeha, were shareholders in claims in the Te Aroha district.)

text: Maori at Te Aroha after the opening of the goldfield in 1880 (mostly through Pakeha eyes) As the Maori population continued to decline, the aged rangatira admired by Pakeha (even including those who had fought against the Crown) gradually died off, to be replaced by Maori more noted for their drinking and occasional violence than their prestige. Although concerts and haka were popular with many Pakeha, much Maori behaviour was mocked, including by children. Many Maori were seen as being unsophisticated, unable to express themselves properly in English, and prone to drunkenness and laziness, whereas those who adopted Pakeha ways were praised.
Some Pakeha sympathized with poverty-stricken Maori and regretted the decline of their language. There were many examples of close and friendly relations and of Maori assisting Pakeha in trouble, but in general they lived geographically separate lives. To earn money, Maori were forced to work at road making, timber cutting, gum digging, and farming what land remained in their possession. Most Maori struggled financially, their limited resources being stretched by holding expensive tangi and entertaining visitors – resulting in more land sales. They used the court system to defend their economic interests.
Ngati Rahiri (including supporters of the Kingitanga) were seen as ‘loyal’ to the Crown, and visiting Maori kings received kindly treatment from Pakeha as well as from Maori. 
Poor health prompted some government assistance, but poor housing remained, although some attempts were made to improve it (partly to protect Pakeha from diseases). Before the twentieth century only a few children, mostly ‘half-castes’, were educated. Most Ngati Rahiri were members of the Church of England before being attracted by the new Mormon faith.
Ngati Rahiri participated with Pakeha in horse races, sporting contests, and, especially, rugby, and a few joined the Volunteers. Much less desirable to most residents was their heavy drinking (encouraged by some publicans and their Pakeha drinking buddies), and occasional fights, very occasionally with Pakeha. Overall, Pakeha ways, both good and bad, of necessity were adopted, and Ngati Rahiri became inextricably a subordinate part of the Pakeha community, although still retaining some distinctive features. 

 (Note: Unless otherwise indicated, all those named in this paper, both Maori and Pakeha, were shareholders in claims in the Te Aroha district.)

year: 2016