title: The Longwood Igneous Complex, Southland, New Zealand: A Permo-Jurassic, intra-oceanic, subduction-related, I-type batholithic complex

authors: Price, Richard C.

subjects: gabbro

abstract: The Longwood Igneous Complex (LIC) is located in Southland, New Zealand on the eastern side of the Carboniferous to Cretaceous, I-type, Median Batholith. Intrusives of the Complex range in age from Permian to Jurassic and show trace element characteristics typical of subduction-related magmas. Gabbro, gabbroic diorite and basaltic dyke rocks show trace and minor element patterns and isotopic compositions indicating that they represent magmas generated in an intra-oceanic subduction system. Radiometric ages decrease across the LIC from 254 Ma in the east to 142 Ma in the west and mineral chemistry and mineral phase relationships indicate emplacement at depths between 15 and 25 km. Thus the petrology and geochemistry of the LIC provides the basis for evaluating the composition of lower–middle crust assembled above a long lived intra-oceanic subduction system and we estimate this to be andesitic and similar to bulk continental crust.
Rocks of the LIC range in composition from troctolite and gabbro through diorite to trondhjemite and granite. All of the ultramafic rocks and most of the gabbros have petrographic and geochemical features consistent with a cumulate origin and mineral chemistry shows similarities with arc cumulate sequences from elsewhere. Few of the plutonic rocks making up the LIC have direct analogues among modern intra-oceanic volcanic rocks. The latter are the end products and the former the leftovers from magmatic processes that included fractional crystallisation, crustal assimilation and magma mixing and mingling. Longwood intrusions do not represent magma chambers. They formed as crystal cumulates and mushes left over from the processes that generated magmas erupted at the contemporary volcanic arc.
A correlation between decreasing age of emplacement and Sr and Nd isotopic compositions and inheritance in zircons dated by ion probe are indications of crustal recycling. The generation of felsic rocks in the Longwood intra-oceanic arc involved crustal anatexis and, over the 100 million year history of the arc, the crust evolved towards a composition similar to bulk continental crust and average andesite.
Dioritic rocks of the LIC contain abundant mafic enclaves, which are argued to represent fragments of mafic magma, derived by fractional crystallisation from basalt, which was intruded into a hot but solid or near solid diorite. Heating and remobilisation of the dioritic host disrupted and disaggregated the intruding mafic magma to form enclaves and zones of intrusion breccia that show every variation from liquid–liquid to liquid–solid mingling and mixing. They were then further modified chemically and mineralogically by diffusion of H₂O, Na, P, Ba, REE, and, to a lesser extent, Rb.
Mafic dykes occur throughout the Complex and a number of these are composite with compositions ranging from dolerite through andesite to dacite. The components of composite dykes do not define unequivocal linear mixing trends and hybridisation processes that took place within them have only localised significance; mingling and hybridisation in the composite dykes do not appear to have controlled geochemical variation among the major intrusive units of the Complex.

text: The Longwood Igneous Complex, Southland, New Zealand: A Permo-Jurassic, intra-oceanic, subduction-related, I-type batholithic complex The Longwood Igneous Complex (LIC) is located in Southland, New Zealand on the eastern side of the Carboniferous to Cretaceous, I-type, Median Batholith. Intrusives of the Complex range in age from Permian to Jurassic and show trace element characteristics typical of subduction-related magmas. Gabbro, gabbroic diorite and basaltic dyke rocks show trace and minor element patterns and isotopic compositions indicating that they represent magmas generated in an intra-oceanic subduction system. Radiometric ages decrease across the LIC from 254 Ma in the east to 142 Ma in the west and mineral chemistry and mineral phase relationships indicate emplacement at depths between 15 and 25 km. Thus the petrology and geochemistry of the LIC provides the basis for evaluating the composition of lower–middle crust assembled above a long lived intra-oceanic subduction system and we estimate this to be andesitic and similar to bulk continental crust.
Rocks of the LIC range in composition from troctolite and gabbro through diorite to trondhjemite and granite. All of the ultramafic rocks and most of the gabbros have petrographic and geochemical features consistent with a cumulate origin and mineral chemistry shows similarities with arc cumulate sequences from elsewhere. Few of the plutonic rocks making up the LIC have direct analogues among modern intra-oceanic volcanic rocks. The latter are the end products and the former the leftovers from magmatic processes that included fractional crystallisation, crustal assimilation and magma mixing and mingling. Longwood intrusions do not represent magma chambers. They formed as crystal cumulates and mushes left over from the processes that generated magmas erupted at the contemporary volcanic arc.
A correlation between decreasing age of emplacement and Sr and Nd isotopic compositions and inheritance in zircons dated by ion probe are indications of crustal recycling. The generation of felsic rocks in the Longwood intra-oceanic arc involved crustal anatexis and, over the 100 million year history of the arc, the crust evolved towards a composition similar to bulk continental crust and average andesite.
Dioritic rocks of the LIC contain abundant mafic enclaves, which are argued to represent fragments of mafic magma, derived by fractional crystallisation from basalt, which was intruded into a hot but solid or near solid diorite. Heating and remobilisation of the dioritic host disrupted and disaggregated the intruding mafic magma to form enclaves and zones of intrusion breccia that show every variation from liquid–liquid to liquid–solid mingling and mixing. They were then further modified chemically and mineralogically by diffusion of H₂O, Na, P, Ba, REE, and, to a lesser extent, Rb.
Mafic dykes occur throughout the Complex and a number of these are composite with compositions ranging from dolerite through andesite to dacite. The components of composite dykes do not define unequivocal linear mixing trends and hybridisation processes that took place within them have only localised significance; mingling and hybridisation in the composite dykes do not appear to have controlled geochemical variation among the major intrusive units of the Complex.

year: 2011

title: Hydraulic responses of whole vines and individual roots of kiwifruit (Actinidia chinensis) following root severance

authors: Black, Marykate Z.

subjects: Actinidia

abstract: Whole vine (Kplant) and individual root (Kroot) hydraulic conductances were measured in kiwifruit (Actinidia chinensis Planch. var. chinensis ‘Hort16A’) vines to observe hydraulic responses following partial root system excision. Heat dissipation and compensation heat pulse techniques were used to measure sap flow in trunks and individual roots, respectively. Sap flux and measurements of xylem pressure potential (Ψ) were used to calculate Kplant and Kroot in vines with zero and ∼80% of roots severed. Whole vine transpiration (E), Ψ and Kplant were significantly reduced within 24 h of root pruning, and did not recover within 6 weeks. Sap flux in intact roots increased within 24 h of root pruning, driven by an increase in the pressure gradient between the soil and canopy and without any change in root hydraulic conductance. Photosynthesis (A) and stomatal conductance (gs) were reduced, without significant effects on leaf internal CO2 concentration (ci). Shoot growth rates were maintained; fruit growth and dry matter content were increased following pruning. The woody roots of kiwifruit did not demonstrate a rapid dynamic response to root system damage as has been observed previously in monocot seedlings. Increased sap flux in intact roots with no change in Kroot and only a moderate decline in shoot A suggests that under normal growing conditions root hydraulic conductance greatly exceeds requirements for adequate shoot hydration.

text: Hydraulic responses of whole vines and individual roots of kiwifruit (Actinidia chinensis) following root severance Whole vine (Kplant) and individual root (Kroot) hydraulic conductances were measured in kiwifruit (Actinidia chinensis Planch. var. chinensis ‘Hort16A’) vines to observe hydraulic responses following partial root system excision. Heat dissipation and compensation heat pulse techniques were used to measure sap flow in trunks and individual roots, respectively. Sap flux and measurements of xylem pressure potential (Ψ) were used to calculate Kplant and Kroot in vines with zero and ∼80% of roots severed. Whole vine transpiration (E), Ψ and Kplant were significantly reduced within 24 h of root pruning, and did not recover within 6 weeks. Sap flux in intact roots increased within 24 h of root pruning, driven by an increase in the pressure gradient between the soil and canopy and without any change in root hydraulic conductance. Photosynthesis (A) and stomatal conductance (gs) were reduced, without significant effects on leaf internal CO2 concentration (ci). Shoot growth rates were maintained; fruit growth and dry matter content were increased following pruning. The woody roots of kiwifruit did not demonstrate a rapid dynamic response to root system damage as has been observed previously in monocot seedlings. Increased sap flux in intact roots with no change in Kroot and only a moderate decline in shoot A suggests that under normal growing conditions root hydraulic conductance greatly exceeds requirements for adequate shoot hydration.

year: 2011

title: Mokopuna rising: Developing a best practice for early intervention in whanau violence

authors: Cooper, Erana

subjects: Maori

abstract: In a very difficult meeting, an extremely unpleasant man was concerned about the possible loss of his power and the continuation of his plans and dreams for the future. And I said, yeah well, you should be worried, because according to your philosophy, when you’re dead, you’re dead. But when I’m dead, my mokopuna will be rising. (Personal Communication, Rob Cooper, 2007) 
“Mokopuna Rising” is about claiming space for Maori to define best practice for reducing and avoiding whanau violence1 It is research in progress towards a PhD, being carried out with the Ngati Hine Health Trust, in Te Taitokerau (Northland).

text: Mokopuna rising: Developing a best practice for early intervention in whanau violence In a very difficult meeting, an extremely unpleasant man was concerned about the possible loss of his power and the continuation of his plans and dreams for the future. And I said, yeah well, you should be worried, because according to your philosophy, when you’re dead, you’re dead. But when I’m dead, my mokopuna will be rising. (Personal Communication, Rob Cooper, 2007) 
“Mokopuna Rising” is about claiming space for Maori to define best practice for reducing and avoiding whanau violence1 It is research in progress towards a PhD, being carried out with the Ngati Hine Health Trust, in Te Taitokerau (Northland).

year: 2008