title: Sequence stratigraphic, paleoenvironmental, and chronological analysis of the late neogene Wanganui River section, Wanganui basin

authors: Hayton, Shaun

abstract: Between Taranaki Basin and the central ranges of the North Island, New Zealand, lies the broadly elliptical, back-arc Wanganui Basin, half of which is onshore. This basin covers an area of about 22,000 km², and contains a Plio-Pleistocene sedimentary succession some 4 km thick. Ongoing south- to southeast-ward migration of the basin depocentre and thermally driven uplift to the north have resulted in the development of broad east-west trending stratal belts that young and dip to the south. The Wanganui River intersects these stratal belts and offers the potential to examine the entire late Miocene to late Pliocene succession in the western half of Wanganui Basin.

For the first time the Wanganui River section has been divided into five predominantly planktic foraminiferal biozones (Globorotalia conomiozea zone, G. punticulata zone, G. inflata zone, combined dextral G. crassaformis and Cibicides molestus zone, and dextral G. crassaformis zone), that are linked to the New Zealand stage classification system. The absolute ages implied by these biostratigraphic datums, combined with a magnetostratigraphy being developed for the section, form an age framework for the sedimentary succession exposed in the Wanganui River valley between Tieke and Parakino. The apparently diachronous nature of the datums traditionally tied to the Mangapanian-Waipipian Stage boundary are highlighted.

The lithostratigraphy of the approximately 3600 m thick sedimentary succession between Tieke and Parakino has been analysed and recorded. Three lithotypes (sandstone, siltstone, shellbed) have been identified, with each containing a number of lithofacies. These lithofacies represent a variety of paleoenvironments from nearshore (0-25 m) to slope type (200-600 m) depths, as determined by analysis of the benthic foraminiferal content and sedimentary structures. This study has resulted in the identification of key unit boundaries and has to some degree simplified the nomenclature assigned to this succession, with five discrete units being recognised.

The Matemateaonga Formation is an at least 1570 m-thick late Miocene (lower Kapitean) to Pliocene (mid Opoitian) succession with 31 discrete cyclothems being identified in the section studied. Each cyclothem displays a coarsening upward trend, with most being related to high-order (6ᵗʰ) glacio-eustatic sea-level fluctuations. Some differences are noted between these cyclothems and those modelled by Naish and Kamp (1997), notably the character of the basal boundary and the architecture of the transgressive systems tract.

The Pliocene (mid Opoitian and Waipipian) aged Tangahoe Formation in the Wanganui River valley is predominantly a deep-water (200-600 m) siltstone, within which occur three distinct sandstone-dominated units (Jerusalem, Matahiwi and Koroniti Sandstone Members). The depocentre, in which this unit was deposited, formed in a shallow continental seaway resulting in a foraminiferal signal that was both deep-water and neritic. The sandstone members are composed of multiple mass-emplaced sandstones interbedded with typical Tangahoe Formation siltstone and are interpreted as being slope and basin floor (in terms of the depocentre, rather than a typical continental margin) fan deposits derived from quasi-steady state grain flows.

The Ahurangi Sandstone overlies the siltstone-dominated Tangahoe Formation, with the basal transition occurring over 15 m. The Ahurangi Sandstone is initially massive but becomes bedded in its upper half. This unit is interpreted as reflecting the rapid infilling of the deep-water basin responsible for the development of the Tangahoe Formation. 

The Waipipian and Mangapanian aged cyclothemic Atene Formation overlies the Ahurangi Sandstone and records the return of high-order glacio-eustatic fluctuations as the dominant control on relative sea-level, and thus sedimentation, within a shelf environment. 

The Mangaweka Mudstone is the uppermost unit within this study. The sedimentary succession as observed in the Wanganui River section is interpreted as being deposited in a “giant foreset” type of environment. Using foraminiferal data, the basal boundary of the Mangaweka Mudstone appears time transgressive across the Wanganui Basin.
 
The development of the Wanganui River valley succession between Tieke and Parakino can be subdivided into a series of six phases within an overall subsiding basin. The four complete phases (Ngaporo, Puraroto Caves, Pipiriki and Ranana) show a period of major deepening followed by shallowing before re-establishment of high-order glacio-eustatic sea-level fluctuations as the primary control on relative sea-level. These deepening events have been interpreted as representing stages of tectonically controlled depocentre development. The variability (lithological, architecture and size) in the phases is related to the proximity of the Wanganui River section to the loci of depocentre development. The Ranana phase is regarded as being centrally located, while the Ngaporo and Puraroto Caves phases represent more distal locations relative to their contemporary depocentre(s).

text: Sequence stratigraphic, paleoenvironmental, and chronological analysis of the late neogene Wanganui River section, Wanganui basin Between Taranaki Basin and the central ranges of the North Island, New Zealand, lies the broadly elliptical, back-arc Wanganui Basin, half of which is onshore. This basin covers an area of about 22,000 km², and contains a Plio-Pleistocene sedimentary succession some 4 km thick. Ongoing south- to southeast-ward migration of the basin depocentre and thermally driven uplift to the north have resulted in the development of broad east-west trending stratal belts that young and dip to the south. The Wanganui River intersects these stratal belts and offers the potential to examine the entire late Miocene to late Pliocene succession in the western half of Wanganui Basin.

For the first time the Wanganui River section has been divided into five predominantly planktic foraminiferal biozones (Globorotalia conomiozea zone, G. punticulata zone, G. inflata zone, combined dextral G. crassaformis and Cibicides molestus zone, and dextral G. crassaformis zone), that are linked to the New Zealand stage classification system. The absolute ages implied by these biostratigraphic datums, combined with a magnetostratigraphy being developed for the section, form an age framework for the sedimentary succession exposed in the Wanganui River valley between Tieke and Parakino. The apparently diachronous nature of the datums traditionally tied to the Mangapanian-Waipipian Stage boundary are highlighted.

The lithostratigraphy of the approximately 3600 m thick sedimentary succession between Tieke and Parakino has been analysed and recorded. Three lithotypes (sandstone, siltstone, shellbed) have been identified, with each containing a number of lithofacies. These lithofacies represent a variety of paleoenvironments from nearshore (0-25 m) to slope type (200-600 m) depths, as determined by analysis of the benthic foraminiferal content and sedimentary structures. This study has resulted in the identification of key unit boundaries and has to some degree simplified the nomenclature assigned to this succession, with five discrete units being recognised.

The Matemateaonga Formation is an at least 1570 m-thick late Miocene (lower Kapitean) to Pliocene (mid Opoitian) succession with 31 discrete cyclothems being identified in the section studied. Each cyclothem displays a coarsening upward trend, with most being related to high-order (6ᵗʰ) glacio-eustatic sea-level fluctuations. Some differences are noted between these cyclothems and those modelled by Naish and Kamp (1997), notably the character of the basal boundary and the architecture of the transgressive systems tract.

The Pliocene (mid Opoitian and Waipipian) aged Tangahoe Formation in the Wanganui River valley is predominantly a deep-water (200-600 m) siltstone, within which occur three distinct sandstone-dominated units (Jerusalem, Matahiwi and Koroniti Sandstone Members). The depocentre, in which this unit was deposited, formed in a shallow continental seaway resulting in a foraminiferal signal that was both deep-water and neritic. The sandstone members are composed of multiple mass-emplaced sandstones interbedded with typical Tangahoe Formation siltstone and are interpreted as being slope and basin floor (in terms of the depocentre, rather than a typical continental margin) fan deposits derived from quasi-steady state grain flows.

The Ahurangi Sandstone overlies the siltstone-dominated Tangahoe Formation, with the basal transition occurring over 15 m. The Ahurangi Sandstone is initially massive but becomes bedded in its upper half. This unit is interpreted as reflecting the rapid infilling of the deep-water basin responsible for the development of the Tangahoe Formation. 

The Waipipian and Mangapanian aged cyclothemic Atene Formation overlies the Ahurangi Sandstone and records the return of high-order glacio-eustatic fluctuations as the dominant control on relative sea-level, and thus sedimentation, within a shelf environment. 

The Mangaweka Mudstone is the uppermost unit within this study. The sedimentary succession as observed in the Wanganui River section is interpreted as being deposited in a “giant foreset” type of environment. Using foraminiferal data, the basal boundary of the Mangaweka Mudstone appears time transgressive across the Wanganui Basin.
 
The development of the Wanganui River valley succession between Tieke and Parakino can be subdivided into a series of six phases within an overall subsiding basin. The four complete phases (Ngaporo, Puraroto Caves, Pipiriki and Ranana) show a period of major deepening followed by shallowing before re-establishment of high-order glacio-eustatic sea-level fluctuations as the primary control on relative sea-level. These deepening events have been interpreted as representing stages of tectonically controlled depocentre development. The variability (lithological, architecture and size) in the phases is related to the proximity of the Wanganui River section to the loci of depocentre development. The Ranana phase is regarded as being centrally located, while the Ngaporo and Puraroto Caves phases represent more distal locations relative to their contemporary depocentre(s).

year: 1998

title: Necessary connections between distinct existences: A Peircean challenge to Humeanism

authors: Legg, Catherine

subjects: Peirce

abstract: It is hard to overestimate the impact of Hume’s famous dictum: “There are no necessary connections between distinct existences” on the subsequent development of mainstream philosophy. It has not only influenced philosophical thinking about causation, laws of nature and other areas of ‘scientific metaphysics’, but also modality, mathematics, personal identity and very importantly, ethics. But is it true? I argue that Hume uses the supposed axiomatic status of his dictum as a covert means of denying - whilst avoiding an honest metaphysical debate about - the view of scholastic realism. I discuss how Peirce by contrast engaged in this debate, and some of his conclusions.

text: Necessary connections between distinct existences: A Peircean challenge to Humeanism It is hard to overestimate the impact of Hume’s famous dictum: “There are no necessary connections between distinct existences” on the subsequent development of mainstream philosophy. It has not only influenced philosophical thinking about causation, laws of nature and other areas of ‘scientific metaphysics’, but also modality, mathematics, personal identity and very importantly, ethics. But is it true? I argue that Hume uses the supposed axiomatic status of his dictum as a covert means of denying - whilst avoiding an honest metaphysical debate about - the view of scholastic realism. I discuss how Peirce by contrast engaged in this debate, and some of his conclusions.

year: 2012

title: Integrating Maori perspectives into community resilience frameworks for the built environment

authors: Boston, Megan

abstract: Many governments and organisations have attempted to construct frameworks for improving community resilience, particularly as related to the built environment. Many frameworks, globally and locally, take a large overview of society and miss the potential to incorporate cultural, social, and engineering practices followed by indigenous people. However, there is much to learn from the traditional practices of Maori that could directly improve community resilience after a disaster. To date, little research has worked on integrating Maori cultural views into resilience frameworks. Using survey and interview data investigating Maori cultural views on resilience and aspects of the built environment, five Maori values were identified to strengthen resilience. These values are matauranga (knowledge), kotahitanga (unity), kaitiakitanga (guardianship), whakawhanaungatanga (relationships), and manakitanga (extending love). Further, communities can increase community cohesion and unity through adapting building and community layouts learned from observing traditional Maori practices, such as a central marae.

text: Integrating Maori perspectives into community resilience frameworks for the built environment Many governments and organisations have attempted to construct frameworks for improving community resilience, particularly as related to the built environment. Many frameworks, globally and locally, take a large overview of society and miss the potential to incorporate cultural, social, and engineering practices followed by indigenous people. However, there is much to learn from the traditional practices of Maori that could directly improve community resilience after a disaster. To date, little research has worked on integrating Maori cultural views into resilience frameworks. Using survey and interview data investigating Maori cultural views on resilience and aspects of the built environment, five Maori values were identified to strengthen resilience. These values are matauranga (knowledge), kotahitanga (unity), kaitiakitanga (guardianship), whakawhanaungatanga (relationships), and manakitanga (extending love). Further, communities can increase community cohesion and unity through adapting building and community layouts learned from observing traditional Maori practices, such as a central marae.

year: 2022