title: Volcanic History and Eruption Processes of Blue Lake Crater, Tongariro

authors: Simons, Benjamin Clifford

subjects: Volcanology

abstract: Blue Lake Crater (BLC) is a volcanic crater lake situated on the northern end of the Tongariro Volcanic Centre (TgVC) and is one of at least 11 vents that have been active since c. 25 ka. The stratigraphy of the proximal-to-vent deposits and associated eruption history of BLC has been poorly constrained compared to many of the other young TgVC vents. The resurgence of volcanic activity on the northern end of the TgVC in 2012 prompted research into other young northern vents to determine if any relationships exist, and whether these vents are capable of future eruptions.
The stratigraphy, geomorphological and facies characteristics have been compiled from detailed field mapping and stratigraphic logs around the BLC pyroclastic rim and the Mangahouhounui Valley. BLC is surrounded by a rim of agglutinates and pyroclastic fall deposits that drape over older Tongariro landforms. The northern rim is comprised of Rotopaunga peak (~130 m above Blue Lake) which includes a series of four thick, welded agglutinate units (the Rotopaunga Agglutinates) which are considered to pre-date BLC, overlain by a succession of scoria and spatter beds (the Rotopaunga Scorias) which are sourced, at least in part, from BLC. A discontinuous exposure of agglutinate, up to 8 m thick, mantles the western and southern rim. A ~4 m thick, ~700 m long a'a lava flow derived from BLC extends over the eastern rim into the Mangahouhounui valley. The proximal-vent-forming deposits are comprised of non to intensely welded and agglutinated spatter and scoria and have all been produced by explosive Hawaiian-and Strombolian-style fire-fountaining. These deposits do not represent the original crater-forming event however, which based on geomorphology, is suggested to have been pheatomagmatic.
Petrography, electron microprobe and x-ray fluorescence analyses were carried out on a selection of samples. The deposits are all plagioclase-dominated porphyritic pyroxene andesites and basaltic andesites, some of which contain rare olivine. A lack of phenocryst and whole rock geochemical trends through the stratigraphic sequence indicates that there is no progression or evolution of the magmas through time, and that multiple magma batches mingled prior to eruption.
The hazards associated with BLC include: phreatomagmatic pyroclastic density currents, ballistic blocks and bombs and fire-fountaining, and lahars caused either by a future eruption or from the failure of the BLC rim.
The northern vents of the TgVC (North Crater, Te Maari craters and BLC) are closely spaced and of a similar age and similar geochemical composition. BLC and Te Maari are likely to share a similar subsurface hydrothermal system and a spatial distribution of seismicity, although these alone do not imply a link in subsurface magma plumbing between the two vents.

text: Volcanic History and Eruption Processes of Blue Lake Crater, Tongariro Blue Lake Crater (BLC) is a volcanic crater lake situated on the northern end of the Tongariro Volcanic Centre (TgVC) and is one of at least 11 vents that have been active since c. 25 ka. The stratigraphy of the proximal-to-vent deposits and associated eruption history of BLC has been poorly constrained compared to many of the other young TgVC vents. The resurgence of volcanic activity on the northern end of the TgVC in 2012 prompted research into other young northern vents to determine if any relationships exist, and whether these vents are capable of future eruptions.
The stratigraphy, geomorphological and facies characteristics have been compiled from detailed field mapping and stratigraphic logs around the BLC pyroclastic rim and the Mangahouhounui Valley. BLC is surrounded by a rim of agglutinates and pyroclastic fall deposits that drape over older Tongariro landforms. The northern rim is comprised of Rotopaunga peak (~130 m above Blue Lake) which includes a series of four thick, welded agglutinate units (the Rotopaunga Agglutinates) which are considered to pre-date BLC, overlain by a succession of scoria and spatter beds (the Rotopaunga Scorias) which are sourced, at least in part, from BLC. A discontinuous exposure of agglutinate, up to 8 m thick, mantles the western and southern rim. A ~4 m thick, ~700 m long a'a lava flow derived from BLC extends over the eastern rim into the Mangahouhounui valley. The proximal-vent-forming deposits are comprised of non to intensely welded and agglutinated spatter and scoria and have all been produced by explosive Hawaiian-and Strombolian-style fire-fountaining. These deposits do not represent the original crater-forming event however, which based on geomorphology, is suggested to have been pheatomagmatic.
Petrography, electron microprobe and x-ray fluorescence analyses were carried out on a selection of samples. The deposits are all plagioclase-dominated porphyritic pyroxene andesites and basaltic andesites, some of which contain rare olivine. A lack of phenocryst and whole rock geochemical trends through the stratigraphic sequence indicates that there is no progression or evolution of the magmas through time, and that multiple magma batches mingled prior to eruption.
The hazards associated with BLC include: phreatomagmatic pyroclastic density currents, ballistic blocks and bombs and fire-fountaining, and lahars caused either by a future eruption or from the failure of the BLC rim.
The northern vents of the TgVC (North Crater, Te Maari craters and BLC) are closely spaced and of a similar age and similar geochemical composition. BLC and Te Maari are likely to share a similar subsurface hydrothermal system and a spatial distribution of seismicity, although these alone do not imply a link in subsurface magma plumbing between the two vents.

year: 2014

title: Ecophysiological adaptations of the lichen genera pseudocyphellaria and sticta to south temperate rainforests

authors: Green, T.G. Allan

abstract: Temperate rainforests are a poorly researched habitat with respect to lichen ecophysiology in comparison to desert and polar regions. The evergreen, broadleaf forests provide a dim, moist environment that is relatively stable throughout the year. Lichens are abundant in both quantity and species diversity with the large foliose genera Sticta and Pseudocyphellaria normally being dominant, visually and in terms of biomass. These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1-μmol m−2s−1, PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity. Photobiont versatility is also a feature of these genera. Photosymbiodemes occur, i.e. a single thallus containing both green algal and cyanobacterial sectors. Because the different sectors have the same fungal partner and grow in the same habitat, it is possible to investigate whether particular physiological traits are photobiont determined. The ability to recover photosynthetic activity in humid air is confined to thalli with green algal photobionts whilst the inability of thalli containing cyanobacterial photobionts to tolerate high light stress may be related to their lack of a protective xanthophyll cycle.

text: Ecophysiological adaptations of the lichen genera pseudocyphellaria and sticta to south temperate rainforests Temperate rainforests are a poorly researched habitat with respect to lichen ecophysiology in comparison to desert and polar regions. The evergreen, broadleaf forests provide a dim, moist environment that is relatively stable throughout the year. Lichens are abundant in both quantity and species diversity with the large foliose genera Sticta and Pseudocyphellaria normally being dominant, visually and in terms of biomass. These lichens exhibit a great diversity of both form and habitat range. Physiological and morphological adaptation has also been demonstrated. Pseudocyphellaria dissimilis shows changes in thallus water storage capacity with evaporative demand and is also highly shade-adapted. The species has the lowest light saturation and compensation values for photosynthesis yet known for lichens (20 and 1-μmol m−2s−1, PAR, respectively). Unexpectedly it is also highly desiccation-sensitive with some thalli being killed after only 20 h exposure to 15% relative humidity. Photobiont versatility is also a feature of these genera. Photosymbiodemes occur, i.e. a single thallus containing both green algal and cyanobacterial sectors. Because the different sectors have the same fungal partner and grow in the same habitat, it is possible to investigate whether particular physiological traits are photobiont determined. The ability to recover photosynthetic activity in humid air is confined to thalli with green algal photobionts whilst the inability of thalli containing cyanobacterial photobionts to tolerate high light stress may be related to their lack of a protective xanthophyll cycle.

year: 1991

title: Personality and Representation in Environmental Law

authors: Daya-Winterbottom, Trevor

abstract: Jorge Vinuales from the University of Cambridge observed in his working paper on “Law and the Anthropocene” that law is founded on a series of core concepts, such as, “legal personality, representation, obligation, debt, causality or damage” (CEENRG Working Papers 2016- 4, page 49). This led him to note that a “significant problem” faced by environmental law is how to flesh out these core concepts in relation to the protection of the environment (page 53). For example, should we regard natural resources (e.g. rivers or mountains) as “subjects” of environmental law with their “own interests and capacity to act (through representation)”, or merely as the “objects” of environmental law – to be protected either “directly” as specific natural resources, or “indirectly” via the protection of the environment generally (page 53). This article interrogates these perspectives by reference to recent New Zealand developments.

text: Personality and Representation in Environmental Law Jorge Vinuales from the University of Cambridge observed in his working paper on “Law and the Anthropocene” that law is founded on a series of core concepts, such as, “legal personality, representation, obligation, debt, causality or damage” (CEENRG Working Papers 2016- 4, page 49). This led him to note that a “significant problem” faced by environmental law is how to flesh out these core concepts in relation to the protection of the environment (page 53). For example, should we regard natural resources (e.g. rivers or mountains) as “subjects” of environmental law with their “own interests and capacity to act (through representation)”, or merely as the “objects” of environmental law – to be protected either “directly” as specific natural resources, or “indirectly” via the protection of the environment generally (page 53). This article interrogates these perspectives by reference to recent New Zealand developments.

year: 2018-02-06