title: Hydrocarbon seep-carbonates of a Miocene forearc (East Coast Basin), North Island, New Zealand

authors: Campbell, Kathleen A.

subjects: hydrocarbon seep-carbonate

abstract: An ancient hydrocarbon seep province of 14 isolated, authigenic carbonate deposits has been identified in fine-grained, deep-marine siliciclastic strata of the Miocene East Coast Basin, North Island, New Zealand. These forearc sediments have been uplifted and complexly deformed into accretionary ridges, adjacent to the still-active Hikurangi convergent margin. Older active and passive margin strata (mid-Cretaceous to Oligocene in age) underlie the Neogene sequence, and contain oil- and gas-prone source rocks. Older Mesozoic meta-sedimentary rocks constitute the backstop against which the current phase of subduction-related sedimentation has accumulated (~ 24 Ma–present). The seep-carbonates (up to 10 m thick, 200 m across) archive methane signatures in their depleted carbon isotopes (to δ13C –51.7‰ PDB), and contain chemosynthesis-based paleocommunities (e.g. worm tubes, bathymodioline mussels, and vesicomyid, lucinid and thyasirid bivalves) typical of other Cenozoic and modern seeps. Northern and southern sites are geographically separated, and exhibit distinct lithological and faunal differences. Structural settings are variable. Seep-associated lithologies also are varied, and suggest carbonate development in sub-seafloor, seafloor and physically reworked (diapiric expansion, gas explosion, gravity slide or debris flow) settings, similar to Italian Apennine seep deposits of overlapping ages.
Peculiar attributes of the New Zealand Miocene seep deposits are several, including digitate thrombolites of clotted microbial micrite encased in thick, isopachous horizons and botryoids of aragonite. Seep plumbing features are also well-exposed at some sites, displaying probable gas-explosion breccias filled with aragonite, tubular concretions (fluid conduits), and carbonate-cemented, thin sandstone beds and burrows within otherwise impermeable mudstones. A few seeps were large enough to develop talus-debris piles on their flanks, which were populated by lucinid bivalves and terebratulid brachiopods. Firmgrounds and hardgrounds were common, as evidenced by trace fossil associations or caryophyllid coral thickets atop some seep-carbonate deposits. Thus, the New Zealand examples show strong evidence of formation in sediments at or just beneath the seafloor, but some were clearly exhumed by erosion to sustain later non-seep, epifaunal and boring paleocommunities.

text: Hydrocarbon seep-carbonates of a Miocene forearc (East Coast Basin), North Island, New Zealand An ancient hydrocarbon seep province of 14 isolated, authigenic carbonate deposits has been identified in fine-grained, deep-marine siliciclastic strata of the Miocene East Coast Basin, North Island, New Zealand. These forearc sediments have been uplifted and complexly deformed into accretionary ridges, adjacent to the still-active Hikurangi convergent margin. Older active and passive margin strata (mid-Cretaceous to Oligocene in age) underlie the Neogene sequence, and contain oil- and gas-prone source rocks. Older Mesozoic meta-sedimentary rocks constitute the backstop against which the current phase of subduction-related sedimentation has accumulated (~ 24 Ma–present). The seep-carbonates (up to 10 m thick, 200 m across) archive methane signatures in their depleted carbon isotopes (to δ13C –51.7‰ PDB), and contain chemosynthesis-based paleocommunities (e.g. worm tubes, bathymodioline mussels, and vesicomyid, lucinid and thyasirid bivalves) typical of other Cenozoic and modern seeps. Northern and southern sites are geographically separated, and exhibit distinct lithological and faunal differences. Structural settings are variable. Seep-associated lithologies also are varied, and suggest carbonate development in sub-seafloor, seafloor and physically reworked (diapiric expansion, gas explosion, gravity slide or debris flow) settings, similar to Italian Apennine seep deposits of overlapping ages.
Peculiar attributes of the New Zealand Miocene seep deposits are several, including digitate thrombolites of clotted microbial micrite encased in thick, isopachous horizons and botryoids of aragonite. Seep plumbing features are also well-exposed at some sites, displaying probable gas-explosion breccias filled with aragonite, tubular concretions (fluid conduits), and carbonate-cemented, thin sandstone beds and burrows within otherwise impermeable mudstones. A few seeps were large enough to develop talus-debris piles on their flanks, which were populated by lucinid bivalves and terebratulid brachiopods. Firmgrounds and hardgrounds were common, as evidenced by trace fossil associations or caryophyllid coral thickets atop some seep-carbonate deposits. Thus, the New Zealand examples show strong evidence of formation in sediments at or just beneath the seafloor, but some were clearly exhumed by erosion to sustain later non-seep, epifaunal and boring paleocommunities.

year: 2008

title: The nature of natural: defining natural character for the New Zealand context

authors: Froude, Victoria A.

subjects: baselines

abstract: New Zealand has a long-standing statutory policy goal to preserve the natural character of the coastal environment and various freshwater environments and their margins. In the absence of an authoritative definition, it has not been possible to develop a method to measure natural character and its change, nor the outcomes of the long-standing national policy goal. Here we develop a definition of natural character that is relevant and useful in the New Zealand environmental, cultural and legal/policy context. Literature-derived interpretations of natural character and equivalent concepts are evaluated as to their potential suitability for developing a biophysical definition of natural character. Using a set of carefully designed criteria a subset of interpretations are condensed into a definition of natural character. The application of this definition is qualified following consideration of the literature addressing human perception and experiences of natural character. Appropriate reference conditions and baselines for evaluating natural character in different contexts are discussed.

text: The nature of natural: defining natural character for the New Zealand context New Zealand has a long-standing statutory policy goal to preserve the natural character of the coastal environment and various freshwater environments and their margins. In the absence of an authoritative definition, it has not been possible to develop a method to measure natural character and its change, nor the outcomes of the long-standing national policy goal. Here we develop a definition of natural character that is relevant and useful in the New Zealand environmental, cultural and legal/policy context. Literature-derived interpretations of natural character and equivalent concepts are evaluated as to their potential suitability for developing a biophysical definition of natural character. Using a set of carefully designed criteria a subset of interpretations are condensed into a definition of natural character. The application of this definition is qualified following consideration of the literature addressing human perception and experiences of natural character. Appropriate reference conditions and baselines for evaluating natural character in different contexts are discussed.

year: 2010

title: Closing geographical distances: The value of a New Zealand perspective on the admission policy of a Native Hawaiian School

authors: Hemi, Keakaokawai Varner

subjects: Racial discrimination

abstract: This article examines the legal narratives evident in the American federal court decision in Doe v Kamehameha Schools (Kamehameha).' The article first describes the historical development of everyone/ no-one, someone and Indigenous equality narratives and their particular impact on the narration of Indigenous peoples in the law. It then examines how the opinions of the United States Ninth Circuit Court of Appeals in this case exhibit significant narrative confusion and distrust about the relationship between Indigenous identity and equality, with the Ninth Circuit interpreting the Native Hawaiian schools' preference for Native Hawaiian students as either reverse racial discrimination or an exception to the general rule of homogeneity and anonymity. For comparison, the article then examines similar equality narratives in New Zealand law, which reveal few legal challenges to admission policies which, either explicitly or implicitly, prefer Maori and demonstrate a narrative complementarity between equality and Indigenous identity. The article recognises that, while complementarity could clarify the narrative issues in Kamehameha for future American federal courts, it also provides the opportunity for New Zealand to pause and reflect. Ultimately, the article advocates a weaving of equality narratives across geographical distances.

text: Closing geographical distances: The value of a New Zealand perspective on the admission policy of a Native Hawaiian School This article examines the legal narratives evident in the American federal court decision in Doe v Kamehameha Schools (Kamehameha).' The article first describes the historical development of everyone/ no-one, someone and Indigenous equality narratives and their particular impact on the narration of Indigenous peoples in the law. It then examines how the opinions of the United States Ninth Circuit Court of Appeals in this case exhibit significant narrative confusion and distrust about the relationship between Indigenous identity and equality, with the Ninth Circuit interpreting the Native Hawaiian schools' preference for Native Hawaiian students as either reverse racial discrimination or an exception to the general rule of homogeneity and anonymity. For comparison, the article then examines similar equality narratives in New Zealand law, which reveal few legal challenges to admission policies which, either explicitly or implicitly, prefer Maori and demonstrate a narrative complementarity between equality and Indigenous identity. The article recognises that, while complementarity could clarify the narrative issues in Kamehameha for future American federal courts, it also provides the opportunity for New Zealand to pause and reflect. Ultimately, the article advocates a weaving of equality narratives across geographical distances.

year: 2016