50thKaikoura05 -1- Kaikoura 2005 CHARACTERISATION OF NEW ...

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Generic recommendations are presented for measures that will decrease the vulnerability of dairy farms to tephra fall hazards. These include a modern, well maintained electrical power supply, large covered water storage capacity, reserves of supplementary feeds, tractor with bucket or grader blade attachments, spare air and oil filters for engines, air compressor for blowing tephra out of machinery, and appropriate knowledge of rehabilitation strategies for pastures covered with tephra. POSTER TAPHONOMY OF A HOLOCENE MOA FEN DEPOSIT, STYX VALLEY, CENTRAL OTAGO Jamie R. Wood Department of Geology, University of Otago, P.O. Box 56, Dunedin (wooja716*student.otago.ac.nz) Significant deposits of bones from large, extinct, flightless birds, predominantly moa (Dinornithiformes) and New Zealand goose (Cnemiornis), occur in alkaline mires (fens) throughout New Zealand. Discovery of these sites is usually associated with the digging of drainage ditches, which causes major disturbance to the deposits. As a result, past scientific excavations have tended to be haphazard, and little taphonomic or orientation data is associated with historic collections. Results are presented for a newly discovered, undisturbed moa fen deposit near Paerau in Styx Valley, Central Otago, where 3dimensional long bone position and orientation data wasrecordedduringexcavationofa1x2mLshaped test pit. The age of the deposit is currently being determined but it is likely to be contemporaneous with a similar mid-late Holocene deposit 5km to the east. Bones were generally in poor condition due to infiltration by fine grass roots. The collected assemblage consisted of heavyfooted moa (Pachyornis elephantopus) (Minimum Number of Individuals (M.N.I.) = 11), stout-legged moa (Euryapteryx geranoides) (M.N.I. = 1), South Island giant moa (Dinornis robustus) (M.N.I. = 1), eastern moa (Emeus crassus) (M.N.I. = 2) and South Island goose (Cnemiornis calcitrans) (M.N.I. = 1). Long bones were mostly lying horizontal, as was found in a moa fen excavation at Glencrieff, Canterbury (Worthy & Holdaway 1996), but showed no apparent preferred alignment with respect to compass bearing. Bones were encountered at depths of 200-800mm, but were most abundant from 500-600mm. No articulated bones were found, although bones from individual birds were found in close association. Common quartz and schistose moa gizzard stones were associated with the bones. Some of these are the largest recorded moa gizzard stones, up to 110mm long, and weighing up to 217g. The content of one gizzard included 2.25kg of stones, and clipped twigs of lacebark (Hoheria sp.) and tree daisy (Olearia sp.), up to 16mm diameter. ORAL ANAGLYPHS AS A TOOL FOR VIEWING TAPHONOMY: AN EXAMPLE FROM A HOLOCENE MOA FEN DEPOSIT, STYX VALLEY, CENTRAL OTAGO Jamie R. Wood & Stephen E. Read Department of Geology, University of Otago, P.O. Box 56, Dunedin (wooja716*student.otago.ac.nz) Coloured stereograms, or anaglyphs, are examined as a tool for gaining an overall perspective on the taphonomy of a fossil deposit. The method was trialled using the excavation of a Holocene moa fen deposit, Styx Valley, Central Otago. 3D orientations were recorded for 63 moa leg bones by measuring X,Y,Z coordinates for the proximal end of each bone, bearing and inclination to the distal end of the bone, and bone length. Trigonometry was used to find X,Y,Z coordinates for the distal end of the bone. Proximal and distal coordinates were used to create points in 3D space using the GIS program ArcGIS. Points from the same bone were joined using a purpose-built script ( supplied by Susan Jones, Eagle Technology Group Ltd.). The ground surface and edges of the excavation pit were symbolised and displayed along with the bones (symbolised as simple 3D tubes) in different perspective views. Selected views were then converted to anaglyphs using an inbuilt application of ArcGIS. This provided a useful way of representing bone orientation data, and may have applications for other paleontological researchers. POSTER SEDIMENT DISPERSAL AND DEPOSITION ON A MUDDY CONTINENTAL SHELF AT THE ACTIVE HIKURANGI MARGIN, POVERTY BAY, NEW ZEALAND 1 Matthew Wood, 2 Lionel Carter, 1 Peter Barrett & 1 Andrew Mackintosh 1 School of Earth Sciences, Victoria University of Wellington, PO Box 600, Wellington 2 National Institute of Water and Atmospheric Research, Greta Point, Wellington (woodmatt*student.vuw.ac.nz) 50 th Kaikoura05 -96- Kaikoura 2005
The continental shelf of the Poverty Bay margin is characterised by very high sediment delivery by the muddy Waipaoa River, which is among the largest in New Zealand in terms of suspended sediment load. This situation reflects favourable geological, tectonic and climatic conditions as well as the effects of human settlement and land-use (Foster and Carter, 1997). The Waipaoa provides an opportunity to study how such high discharge systems interact with the marine environment. The main research objective is to determine the spatial distribution of modern sediment on the continental shelf of the Poverty Bay margin, and to understand how the pattern of various seafloor facies have been affected by the hydraulic regime (waves and currents), shelf morphology (including the Lachlan and Ariel anticlines), and sediment supply. This study has been carried out within the research objectives framework of the Margins Source to Sink (S2S) Initiative and this presentation represents an early stage progress report. The study relies on the integration of geophysical data collected on various research cruises, recently collected physical samples and existing environmental databases. A suite of sediment samples, representing the top 1cm of 87 box cores are analysed for grain size distributions. Contour mapping a number of sedimentary parameters, including % mud and mean grain size, constrains the position of various sedimentary facies across the shelf. Preliminary results suggest that terrigenous organic carbon-rich fluid muds predominate in mid-shelf basin depocentres and are likely to represent recent flood deposits. Samples from the landward limb of the Lachlan Anticline are typically sandy shell hash with associated pebbles. This situation reflects the seafloor outcrop of Neogene strata and potentially the winnowing action of ocean currents. Contour mapping of carbon/nitrogen ratios of the sediment will show the varying influences of marine and terrestrial carbon within the shelf sediments, and highlight sediment pathways and depocentres from river plumes. An acoustic facies classification scheme for the shelf is proposed, based on the type of seafloor surface seismic response (diffuse/distinct/hyperbolic), and the degree of seismic subsurface penetration, as shown in 3.5kHz and ‘chirp’ FM pulse (0.5-7.2kHz) seismic profiles. Gas-masking of the subsurface is prevalent across much of the mid-shelf basin. Significant influence of non-tidal currents may be represented by moating of sediments against the western limbs of the growing anticlines of the shelf break. Further mapping work will include seafloor textural mapping from a side-scan sonar and multibeam backscatter datasets. Wave and wind regime datasets and existing knowledge of ocean currents will be integrated with satellite imagery to develop a model to explain sedimentation in both normal and storm conditions, and the timing of muddy flood deposit resuspension events. POSTER HOW STRONG IS THE ALPINE FAULT? EVIDENCE FROM FLUID FLOW AND DEFORMATION PARTITIONING IN THE PACIFIC PLATE HANGING-WALL Ruth H Wightman & Timothy A Little School of Earth Sciences, Victoria University of Wellington, PO Box 600, Wellington (ruth.wightman*vuw.ac.nz) An array of near-vertical backshears in the central Southern Alps are interpreted to have formed sequentially in an escalator-like fashion and to play an important role in channelling the upward flow of metamorphic fluids through this active orogen. The 1-2 km-wide array of backshears is exposed only in the central region of the Southern Alps around Fox and Franz Josef glaciers. There, fluid inclusion, stable isotope, and thermochronometric data indicate shear failure of a transiently embrittled lower crust down to depths of >20 km. In quartzofeldspathic schist, the shears initiated and accumulated slip brittlely (but probably steadily and aseismically) but ductilely in weaker, preexisting quartz veins that were subject to finite shear strains averaging 4.8 ± 0.8. Blunting of the brittle crack-tips into the coherently deformed quartz veins suggests that ductile flow was the ratecontrolling factor during backshear deformation. The backshears are systematically spaced (53 ± 4.7 cm), with an average slip of 14.1 ± 1.2cmina direction pitching 36°SW and are dextral-oblique. Relative to plate motion, they accommodated an excess of margin-parallel dextral-slip. This situation implies some partitioning of oblique motion components between the Alpine Fault and its dextrally wrenched hanging-wall to the east. A corollary to this is that the Alpine Fault, despite its inferred thermally induced weakness, was not weak enough to accommodate perfectly plate motionparallel slip at the time when the shears were active. We infer that presence of fluid in the Pacific Plate crust was integral to the formation and accumulation of shear along these structures. Nearlithostatic fluid pressures were a chief agent that originally triggered deep embrittlement and shear failure at the lower crustal depths. After formation, hydrolytic weakening due to high water fugacity allowed deformation in the fluid-weakened quartz veins to accrue at high strain-rates but without sufficiently high differential stresses to cause their brittle failure. As the strength of these veins controlled that of the backshears terminating into them, this process may have significantly weakened 50 th Kaikoura05 -97- Kaikoura 2005
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CHARACTERISATION OF NEW ZEALAND NEP
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myrtaceous. One 20 mm diameter flow
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ange of lower resolution or fragmen
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CRETACEOUS-EOCENE TRANSGRESSION MAR
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consists of a well-developed canyon
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model. The relative position of the
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converts to plate theory. Thus, the
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and on the following morning the mi
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the LGM grass peak. This period of
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offshore west coast to offshore eas
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4 Institut de Recherche pour le Dé
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VEGETATION AND CLIMATE CHANGE AT TH
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wider range. The youngest layer has
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few normal faults visible especiall
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TRACKING CRUSTAL DIFFERENTIATION AN
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EMPIRICAL SCALING RELATIONS FOR SEI
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hydrovolcanic eruptions then took p
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and that the MTL marks a Late Carbo
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faunal changes within these cores w
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material at subsurface depths of se
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survived through in low numbers in
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in the TVZ and southern Havre Troug
Page 45 and 46: Tephra beds are commonly used to ai
Page 47 and 48: The MCC is bounded by deep-seated t
Page 49 and 50: distal alluvial plains where large
Page 51 and 52: Many of the molluscs in the highly
Page 53 and 54: incremental slip history and paleoe
Page 55 and 56: This paper explores what we know of
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Page 59 and 60: These areas are also described in
Page 61 and 62: 3D IMAGING OF THE FORE- AND BACKTHR
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Page 65 and 66: THE GRIFFENS ROAD TEPHRAS: VALUABLE
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Page 69 and 70: with 63.8%, and then [3] with 49.9%
Page 71 and 72: U-Th-Ra disequilibria data. In part
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Page 85 and 86: The new era of commercial viability
Page 87 and 88: TECTONICS OF THE GALATEA BASIN USIN
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Page 99 and 100: 5 Dept. of Mineral Sciences, Smiths
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