title: Tubular carbonate concretions as hydrocarbon migration pathways? Examples from North Island, New Zealand

authors: Nyman, Stephanie Leigh

subjects: Tubular concretions

abstract: Cold seep carbonate deposits are associated with the development on the sea floor of distinctive chemosyn¬thetic animal communities and carbonate minerali¬sation as a consequence of microbially mediated anaerobic oxidation of methane. Several possible sources of the methane exist, identifiable from the carbon isotope values of the carbonate precipitates. In the modern, seep carbonates can occur on the sea floor above petroleum reservoirs where an important origin can be from ascending thermogenic hydrocar¬bons. The character of geological structures marking the ascent pathways from deep in the subsurface to shallow subsurface levels are poorly understood, but one such structure resulting from focused fluid flow may be tubular carbonate concretions.
Several mudrock-dominated Cenozoic (especially Miocene) sedimentary formations in the North Island of New Zealand include carbonate concretions having a wide range of tubular morphologies. The concretions are typically oriented at high angles to bedding, and often have a central conduit that is either empty or filled with late stage cements. Stable isotope analyses (δ13C, δ18O) suggest that the carbonate cements in the concretions precipitated mainly from ascending methane, likely sourced from a mixture of deep thermogenic and shallow biogenic sources. A clear link between the tubular concretions and overlying paleo-sea floor seep-carbonate deposits exists at some sites.
We suggest that the tubular carbonate concretions mark the subsurface plumbing network of cold seep systems. When exposed and accessible in outcrop, they afford an opportunity to investigate the geochemical evolution of cold seeps, and possibly also the nature of linkages between subsurface and surface portions of such a system. Seep field development has implications for the characterisation of fluid flow in sedimentary basins, for the global carbon cycle, for exerting a biogeochemical influence on the development of marine communities, and for the evaluation of future hydrocarbon resources, recovery, and drilling and production hazards. These matters remain to be fully assessed within a petroleum systems framework for New Zealand’s Cenozoic sedimentary basins.

text: Tubular carbonate concretions as hydrocarbon migration pathways? Examples from North Island, New Zealand Cold seep carbonate deposits are associated with the development on the sea floor of distinctive chemosyn¬thetic animal communities and carbonate minerali¬sation as a consequence of microbially mediated anaerobic oxidation of methane. Several possible sources of the methane exist, identifiable from the carbon isotope values of the carbonate precipitates. In the modern, seep carbonates can occur on the sea floor above petroleum reservoirs where an important origin can be from ascending thermogenic hydrocar¬bons. The character of geological structures marking the ascent pathways from deep in the subsurface to shallow subsurface levels are poorly understood, but one such structure resulting from focused fluid flow may be tubular carbonate concretions.
Several mudrock-dominated Cenozoic (especially Miocene) sedimentary formations in the North Island of New Zealand include carbonate concretions having a wide range of tubular morphologies. The concretions are typically oriented at high angles to bedding, and often have a central conduit that is either empty or filled with late stage cements. Stable isotope analyses (δ13C, δ18O) suggest that the carbonate cements in the concretions precipitated mainly from ascending methane, likely sourced from a mixture of deep thermogenic and shallow biogenic sources. A clear link between the tubular concretions and overlying paleo-sea floor seep-carbonate deposits exists at some sites.
We suggest that the tubular carbonate concretions mark the subsurface plumbing network of cold seep systems. When exposed and accessible in outcrop, they afford an opportunity to investigate the geochemical evolution of cold seeps, and possibly also the nature of linkages between subsurface and surface portions of such a system. Seep field development has implications for the characterisation of fluid flow in sedimentary basins, for the global carbon cycle, for exerting a biogeochemical influence on the development of marine communities, and for the evaluation of future hydrocarbon resources, recovery, and drilling and production hazards. These matters remain to be fully assessed within a petroleum systems framework for New Zealand’s Cenozoic sedimentary basins.

year: 2006

title: Phosphine functionalized polyaniline nanostructures

authors: Laslau, Cosmin

subjects: polyaniline

abstract: We study the problem of limited functionalization options for polyaniline through the surface attachment of phosphine coupling reagents. These studied linkers are P(CH₂OH)₃ and Ph₂PCH₂OH, and are attached to both conventional and nanostructured polyaniline. Additionally, model compounds are considered, extending the scope of our analysis. The successful attachment results indicate the potential for further functionalization, using the hydroxymethyl terminal groups of the phosphines for primary and secondary amine chemistry. These results should enable the development of sensitive and molecule-specific polyaniline-based devices.

text: Phosphine functionalized polyaniline nanostructures We study the problem of limited functionalization options for polyaniline through the surface attachment of phosphine coupling reagents. These studied linkers are P(CH₂OH)₃ and Ph₂PCH₂OH, and are attached to both conventional and nanostructured polyaniline. Additionally, model compounds are considered, extending the scope of our analysis. The successful attachment results indicate the potential for further functionalization, using the hydroxymethyl terminal groups of the phosphines for primary and secondary amine chemistry. These results should enable the development of sensitive and molecule-specific polyaniline-based devices.

year: 2010

title: Anō, ko te Riu ō Tāne Mahuta Possibilities and Challenges in a Ngāti Rangiwewehi Curriculum

authors: Mahuika, Rangimarie

subjects: Curriculum

abstract: This thesis considers how a curriculum might form a useful tool in meeting the needs and aspirations of Ngāti Rangiwewehi, a small, but dynamic tribe, who occupy specific territory from the north western shores of Lake Rotorua into the eastern Bay of Plenty of the North Island of New Zealand. In contemplating the potential benefits of a curriculum, this study begins by examining the epistemological frames of reference crucial to understanding how the tribe views the world around them, and their positioning within it. The thesis goes on to explore the pedagogical approaches specific to the iwi, and concludes by assessing the extent to which a curriculum is a viable means of maintaining and empowering Rangiwewehi mātauranga, and their underlying ambitions, and goals. Whether ‘curriculum’ is an appropriate framework to describe the way Ngāti Rangiwewehi view our educational processes, is an issue addressed in this study. To this extent, Rangiwewehi perspectives are intentionally privileged allowing appropriate representation of our understandings and aspirations. Eighteen people were interviewed as part of this study, yet many other voices included here were recorded during a tribal wānanga held in late 2010. Their accounts provide the core ideas and positions at work in this thesis, and are invaluable for the depth and texture they offer. An emphasis on the qualitative data collected here is important in allowing their words to take centre stage. In conveying their views and stories, three major themes emerged: these were people, place, and survival. Woven through the body of the thesis, these themes work to illustrate the key designs and patterns that were seen as fundamental to a Rangiwewehi way of viewing the world. Place and people, for instance, were affirmed as crucial to both the pedagogical and epistemological beliefs and practices maintained across generations. Similarly, the theme of survival was deemed a significant thread in comprehending the struggle and self-determination inherent in the tribe’s sense of identity and knowing. These themes reflect convictions shared across the iwi, highlighting the importance of understanding Ngāti Rangiwewehi by first listening to what they have to say about themselves and their curriculum.

text: Anō, ko te Riu ō Tāne Mahuta Possibilities and Challenges in a Ngāti Rangiwewehi Curriculum This thesis considers how a curriculum might form a useful tool in meeting the needs and aspirations of Ngāti Rangiwewehi, a small, but dynamic tribe, who occupy specific territory from the north western shores of Lake Rotorua into the eastern Bay of Plenty of the North Island of New Zealand. In contemplating the potential benefits of a curriculum, this study begins by examining the epistemological frames of reference crucial to understanding how the tribe views the world around them, and their positioning within it. The thesis goes on to explore the pedagogical approaches specific to the iwi, and concludes by assessing the extent to which a curriculum is a viable means of maintaining and empowering Rangiwewehi mātauranga, and their underlying ambitions, and goals. Whether ‘curriculum’ is an appropriate framework to describe the way Ngāti Rangiwewehi view our educational processes, is an issue addressed in this study. To this extent, Rangiwewehi perspectives are intentionally privileged allowing appropriate representation of our understandings and aspirations. Eighteen people were interviewed as part of this study, yet many other voices included here were recorded during a tribal wānanga held in late 2010. Their accounts provide the core ideas and positions at work in this thesis, and are invaluable for the depth and texture they offer. An emphasis on the qualitative data collected here is important in allowing their words to take centre stage. In conveying their views and stories, three major themes emerged: these were people, place, and survival. Woven through the body of the thesis, these themes work to illustrate the key designs and patterns that were seen as fundamental to a Rangiwewehi way of viewing the world. Place and people, for instance, were affirmed as crucial to both the pedagogical and epistemological beliefs and practices maintained across generations. Similarly, the theme of survival was deemed a significant thread in comprehending the struggle and self-determination inherent in the tribe’s sense of identity and knowing. These themes reflect convictions shared across the iwi, highlighting the importance of understanding Ngāti Rangiwewehi by first listening to what they have to say about themselves and their curriculum.

year: 2011