Dissertations / Theses on the topic 'Fields of Research – 260000 Earth Sciences'

This is the first study of cretaceous or Paleogene Radiolaria from on-land New Zealand. It is based on five Late Cretaceous to Paleocene sections within the Amuri Limestone Group of eastern Marlborough (NE South Island): Woodside Creek, Wharanui Point, Chancet Rocks, Flaxbourne River and Mead Stream. Faunas from coeval sediments at DSDP Site 208 (Lord Howe Rise, north Tasman Sea) are also reexamined. Because diverse and well-preserved radiolarian faunas are common, the location of the Cretaceous/Tertiary (K/T) boundary well-documented, and the earliest Paleocene relatively complete, these sections provide the most complete known record of radiolarian evolution from latest Cretaceous to mid Late Paleocene (c.70-60 Ma). Systematic treatment of K-T transitional faunas was hampered by a dichotomy between Cenozoic and Mesozoic methodologies and nomenclature. To resolve this schism, broad taxonomic definitions are adopted, numerous synonymies are identified, and several revised definitions are proposed for established taxa. Of the 94 taxa recorded, 65 are species or species groups, and 29 are undifferentiated genera or higher level categories. Three new species are described: Amphisphaera aotea n.sp., A. kina n.sp. and Stichomitra wero n.sp. A new latest Cretaceous to mid Late Paleocene zonation is proposed. Six new interval zones are defined by the first appearances of the nominated species. In ascending order these are: Lithomelissa? hoplites (RK9, Cretaceous), Amphisphaera aotea (RP1, Paleocene), A. kina (RP2), Stichomitra granulata (RP3), Buryella foremanae (RP4) and B. tetradica (RP5) Interval Zones. The Late Paleocene Bekoma campechensis Zone of Nishimura (1987) succeeds RP5 at Mead Stream. The K/T boundary does not mark an extinction event for radiolarians, but does coincide with a sudden change from nassellarian to spumellarian dominance. It also coincides with a sudden influx of diatoms in Marlborough, where a fall in sea level appears to have promoted upwelling. Thus, rather than marking a catastrophe, the K/T boundary heralded a period (from RP1 to lower RP3) of great productivity for siliceous plankton. With a return to conditions similar to those of the Cretaceous, later in the Paleocene (upper RP3-RP6), Cretaceous survivors were rapidly replaced by new Tertiary taxa in deep-water settings. However, in shallower settings, many Cretaceous taxa remained abundant throughout the Early Paleocene. Faunal changes at site 208 are similar to those of the deep-water Marlborough sections, but without clear evidence for increased fertilty in the earliest Paleocene.

Radiolaria from Late Eocene to Early Miocene localities in New Zealand are detailed in a series of studies in an attempt to broaden our knowledge of New Zealand Late Paleogene-Early Neogene Radiolaria, and a new technique for investigating Radiolaria is described. Chapter One introduces the studies and the rationale behind each, details the history of radiolarian work in New Zealand, and provides discussion of several points that surfaced during the studies. The points discussed are: radiolarian literature; plate production; scanning electron micrographs versus transmitted light photomicrographs; skeletal terminology; systematic paleontology and the description of new species; radiolarian classification; usefulness of strewn slides. Each study constitutes a published in press, or in review paper and is presented as a chapter. As each chapter is able to stand alone, their abstracts are given below. The reference lists for each paper/chapter have been amalgamated into a master list at the end of the thesis and so do not appear at the end of each chapter: Chapter Two - Seven New Radiolarian Species from the Oligocene of New Zealand Abstract: Seven new radiolarian species from the Oligocene Mahurangi limestone of Northland, New Zealand, are formally described. They are: Dorcadospyris mahurangi (Trissocyclidae), Dictyoprora gibsoni, Siphocampe missilis, Spirocyrtis proboscis (Artostrobiidae), Anthocyrtidium odontatum, Lamprocyclas matakohe (Pterocorythidae), Phormocyrtis vasculum (Theoperidae). Chapter Three – New Radiolaria from the Oligocene and Early Miocene of Northland, New Zealand Abstract: Thirteen new radiolarian species, two new genera and one new combination from the Oligocene and early Miocene of Northland, New Zealand, are formally described - The species are – Heliodiscus tunicatus (Phacodiscidae), Rhopalastrum tritelum (spongodiscidae), Lithomelissa gelasinus, L. maureenae, Lophophaena tekopua (Plagiacanthidae), Valkyria pukapuka (Sethoconidae), Cyrtocapsa osculum, Lophocyrtis (Paralampterium)? inaequalis, Lychnocanium neptunei, Stichocorys negripontensis, Theocorys bianulus, T. perforalvus, T. puriri (Theoperidae); the genera are – Plannapus (Artostrobiidae) and Valkyria (Sethoconidae); the combination is Plannapus microcephalus (Artostrobiidae). Standardised terminology is proposed for internal skeletal elements and external appendages. Emendations are proposed for the family Artostrobiidae and the genera Heliodiscus, Lithomelissa and Cyrtocapsa. Heliodiscus, Cyrtocapsa and Lychnocanium are established as senior synonyms of Astrophacus, Cyrtocapsella and Lychnocanoma respectively. Chapter Four – Early Miocene Radiolaria from Te Kopua Point, Kaipara Harbour, New Zealand Abstract: Radiolaria from the Early Miocene Puriri Formation at Te Kopua Point in the Kaipara area, Northland, New Zealand are documented. Six new species are described - Spongotrochus antoniae (Spongodiscidae), Botryostrobus hollisi, Siphocampe grantmackiei, (Artostrobiidae), Carpocanium rubyae (Carpocaniidae), Anthocyrtidium marieae (Pterocorythidae) and Phormocyrtis alexandrae (Theoperidae). Carpocanium is established as the senior synonym of Carpocanistrum. Chapter Five – Radiolaria from the Oamaru Diatomite, South Island, New Zealand Abstract: Radiolaria from the world-famous Oamaru Diatomite are documented with 24 new species described and three new genera erected The new species are Tricorporisphaera bibula, Zealithapium oamaru (Actionommidae), Plectodiscus runanganus (Porodiscidae), Plannapus hornibrooki, P. mauricei, Spirocyrtis greeni (Artostrobiidae), Botryocella pauciperforata (Cannobotryidae), Carpocanopsis ballisticum (Carpocaniidae), Verutotholus doigi, V. edwardsi, V. mackayi (Neosciadiocapsidae), Lithomelissa lautouri, Velicucullus fragilis (Plagoniidae), Lamprocyclas particollis (Pterocorythidae), Artophormis fluminafauces, Eucyrtidium ventriosum, Eurystomoskevos cauleti, Lophocyrtis (L.) haywardi, Lychnocanium alma, L. waiareka, L. waitaki, Pterosyringium hamata, Sethochytris cavipodis and Thyrsocyrtis (T.?) pingusicoides (Theoperidae). The new genera are Tricorporisphaera, Zealithapium (Actinommidae), and Verutotholus (Neosciadiocapsidae). Emendations are proposed to the family Neosciadiocapsidae and the genus Eurystomoskevos, and Pterosyringium is raised from subgeneric to generic level. Radiolarian faunal composition confirms a Late Eocene age for the Oamaru Diatomite. Chapter Six – Confocal Laser Scanning Microscopy: A New Technique for Investigating and Illustrating Fossil Radiolaria Abstract: Confocal laser scanning microscopy (CLSM), a technique newly applied to the study of fossil Radiolaria, offers the radiolarist clear views of single optical planes of specimens, unhindered by many of the optical effects of conventional light microscopy, while obviating the need to section or break specimens. Resulting images are of a clarity unsurpassed by conventional light microscopy and, as they are saved on computer, are easily viewed, manipulated, enhanced, measured and converted to hard copy. Used in conjunction with common radiolarian study methods CLSM is a powerful tool for gaining additional information with relatively little extra effort. Chapter Seven conveniently summarises taxonomic, stratigraphic and geographic data of all new taxa described, incorporating information gained from the studies and relevant literature. Appendices present the following: data pertaining to all illustrated specimens in this thesis from the University of Auckland Catalogue of Type and Figured Specimens; distribution of Radiolaria at Te Kopua Point; distribution of species and a species list for the Mahurangi Limestone.
Chapter 1 is included in 01front, along with pages 38,93, 130 for additional information. Chapter 2 + of the thesis is now published and subject to copyright restrictions.

The lithologic and biostratigraphic successions of Ururoan, Temaikan and Lower - Middle Heterian (?Sinemurian, Pliensbachian - ?Kimmeridgian) strata from southwest Auckland, south Otago and Southland, New Zealand, are described and discussed. A more logical correlation of the lithologic sequence at Port Waikato with that at Te Akau is proposed. Two new formations are introduced for the sequences on the western limb of the Kawhia Regional Syncline, the Whakapatiki Mudstone for the fine grained lower Kirikiri Group strata in the Awakino Valley and the Gribbon Formation for the Rengarenga Group strata between Marokopa and Mahoenui. In Southland a new formation (Ben Bolt Formation) is proposed for the c.1340m sequence overlying the Flag Hill Sandstone, in turn overlain by a 485m thick, mudstone-dominated formation for which a long disused name is resurrected (Lora Formation). The Lora Formation is in turn overlain by a coarse-grained unit, for which the name West Peak Formation is proposed. In the absence of suitable alternatives, a subdivision of the Ururoan Stage into a Lower Ururoan, the range-zone of pseudaucella marshalli, and an Upper Ururoan, the interval-zone between the last appearance of Pseudaucella marshalli and the first appearance of a Temaikan fauna is proposed. The existing three-fold subdivision of the Temaikan Stage is emended. Belemnopsis mackayi and B. deborahae are retained as the indices of the Temaikan and its lowest subdivision, as they are present in most sections at a consistent stratigraphic position. Retroceramus (Fractoceramus) inconditus is proposed as the basal Middle Temaikan index species. Retroceramus(R.) brownei, which first appears consistently higher than R. inconditus, but below R. marwicki is proposed as the index for the upper Middle Temaikan. Retroceramus (R.) marwicki is proposed as a replacement upper Temaikan index for "Macrocephalites cf. beta-gamma" which is unsuitable. Meleagrinella n. sp. is inconsistent in its first appearance and therefore unsuitable as a Middle Temaikan index and, although confined to this stage, it ranges from Early to early Upper Temaikan. Basal Temaikan Belemnopsis spp. are absent from sections in the Catlins district whereas the earliest Temaikan taxon appearing above typical Ururoan faunas is Meleagrinella n. sp. In the absence of a better alternative Meleagrinella n. sp. is used to mark the base of the stage in the Catlins sections. However, the base of the Temaikan is here likely to be slightly younger than in other sections. Within the redefined Upper Temaikan four subdivisions based on the sequence of Retroceramus species are recognised. The lowest of these is characterised by the first appearance of R. (R.) marwicki, the second by the first appearance of R. (R.) n. sp. A., the third characterised by the first appearance of R. (R.) stehni, and the highest marked by the first appearance of either R. (R ) sp. C. (a wide triangular form) or sp. D. (an ovate flat form). The presence of these two morphologic forms indicate finer zonation of the Upper Temaikan may be possible, with further field work. The Ururoan to Middle Heterian succession of New Zealand is correlated with the international chronostratigraphic scheme based mainly on comparison of New Zealand's Retroceramus succession with that of South America and Indonesia and on relatively rare ammonites. The Ururoan is equivalent to the ?Sinemurian to Late Toarcian, Temaikan to the ?latest Toarcian to Early Callovian and the Early Heterian to the Middle Callovian to latest Middle to Late Oxfordian. Early Ururoan is correlated with the ?Sinemurian to Pliensbachian based on the presence of the ammonite Juraphyllites. Presence of the Early Toarican ammonites Harpoceras cf. falcifer and Dactylioceras spp. in the Late Ururoan indicates a potential international correlation of ?Late Pliensbachian to Late Toarcian. A ?late Toarcian to Aalenian correlation for the Early Temaikan is suggested by the presence of the European belemnite Brevibelus zieteni. Retroceramus (Fractoceramus) inconditus is similar to the Northern hemisphere Mytiloceramus lucifer and the northern hemisphere Retroceramus gr. popovi and thus suggests a latest Aalenian to Early Bajocian correlation of the Middle Temaikan. The earliest Late Middle Temaikan Retroceramus (Retroceramus) marwicki is also present in the Late Bajocian (Rotundum Zone) of Argentina. ?Teloceras gr. banksi, ?stephanoceras (S.) gr. humphriesianum, Chondroceras (C.) gr. evolvescens, C. (C.) cf. recticostatum, and C. (Defonticeras) cf. oblatum are present in the Middle Temaikan reinforcing an earliest to late Early Bajocian correlation for this substage. Toxamblyites aff. densicostatus Sturani, Chondroceras (C.) gr. Evolvescens (Waagen), C. (Schmidtoceras) orbignyanum (Wright), C. (Defonticeras?) sp. indet. occur with Retroceramus marwicki indicating an Early to Late Bajocian correlation for this zone, slightly broader than in Argentina. However, somewhat anomalously the first of these ammonites suggests a Mid Aalenian to Early Bajocian correlation. The succeeding zone (Retroceramus (R.) n. sp A. zone) has yielded the Latest Bathonian Xenocephalites grantmackiei and Lilloettia aff. boesei. Retroceramus(R.)stehni is the index for the third Upper Temaikan Retroceramus zone and is also known from the latest Bathonian to Early Callovian of Argentina. In New Zealand R. stehni is associated with Lilloettia cf. Lilloetensis and Xenocephalites cf. stipanicici which also indicate a latest Bathonian to Early Callovian correlation. The fourth and highest zone of the Upper Temaikan has yielded the ammonites Araucanites marwicki, Eurycephalites gr. extremus, Iniskinites gr. cepoides and Choffatia (Homoeoplanulites) sp. suggesting an Early to Middle Callovian correlation. The overseas relationships of the associated Retroceramus (R.) spp. C. and D. are unknown. The Heterian index Retroceramus (Retroceramus) galoi is of Oxfordian age in Indonesia where it is associated with Malayomaorica malayomaorica. In New Zealand Araucanites marwicki and Sulaites heteriense are present in the Early Heterian, below the incoming of Malayomaorica malayomaorica, low in the range of Retroceramus galoi. The presence of Sulaites high in the Early Heterian suggests a ?Middle to Late Oxfordian correlation while Araucanites indicates the lowest part of the range of Retroceramus galoi could be slightly older, perhaps Upper Callovian. The biostratigraphic scheme presented here is a significant advance on those proposed previously.

This study is based on 15 measured Jurassic to Lower Cretaceous sections and their abundant bivalve faunas distributed mainly in the Nyalam and Gamba districts of southern Xizang. It addresses the establishment of bivalve assemblages, stratigraphic subdivision and correlation, analysis of sedimentary environments, sea-level change and paleogeography in light of the tectonic framework and geological evolution of the Xizang Plateau. The Plateau consists of three terranes: Qangtang, Gangdise and Himalaya They are separated by the sutures: Kunlun-Hoh Xil-Jingsha Jiang, Banggong Co-Nu Jiang, and Yarlu Zangbo Jiang, which represent three closed oceans: Paleo-Tethys, Neo-Tethys and South Xizang Sea. Stratigraphic development of the Jurassic and Lower Cretaceous of southern Xizang is especially closely related to the evolution of the South Xizang Sea Bivalves are one of the most common and important Jurassic and Early Cretaceous fossil groups in the Plateau. From 15 measured sections, 51 bivalve species within 26 genera are described, including 3 new genera and 14 new species. New genera: Vanustus, Yoldioides, Antipectenoides New species: Nuculoma oriens (Nuculidae) Yoldioides jurianoides (Malletiidae) Mesosaccella gangbaensis (Nuculanidae) M. Orienta Grammatodon (Indogrammatodon) sinensis (Parallelodontidae) Oxytoma jiabulensis (Oxytomidae) Meleagrinella minima M. dongshangensis M. sinensis Entolium dongshangensis (Entoliidae) Antipectenoides sinensis Ctenoides shizangensis (Limidae) Anisocardia shizangensis (Arcticidae) Protodiceras lanonglaensis (Megalodontidae) A stratigraphic sequence of ten different bivalve assemblages and four Buchia faunas from the Jurassic to Lower Cretaceous of Nyalam district, and four Jurassic bivalve faunas from the Gamba district are recognised. In addition, the Oxytoma jiabulensis bed and two Meleagrinella beds are also recognised. These assemblages can be seen to be of two types, high and low diversity, indicating different sedimentary environments. These assemblages along with co-existing ammonites also provide a good basis for stratigraphic division and correlation of the sequences. Special attention is given to nomenclatural and other problems associated with the important genus Buchia:. Australobuchia Zakharov is believed to be inseparable generically, and some Xizang species of Buchia an placed in synonymy. On this basis the evolution and migration of the genus is discussed From measured sections in southern Xizang, a comparatively complete Jurassic- Lower Cretaceous sequence has been established, which includes six formations: (in ascending order) Pupugar. Nieniexiongla. Lanongla. Menbu. Xuomo and Gucocun Formations. A new stratigraphic unit, the Gangdong Formation, is established, for Mid-Upper Jurassic strata of the Gamba district. Direct and indirect biostratigraphic correlation within China and between southern Xizang and other places around Gondwanaland is well established. Lithologic features, sedimentary structures and bivalve assemblages allow four environments including nine lithofacies to be recognised in southern Xizang: 1. Inner shelf environment 1] Shoreface sandstone facies 2] Neritic terrigenous clastic facies 3] Open shelf carbonate facies 4] Protected barrier carbonate facies 5] Reef limestone facie 2. Outer shelf environment 6] Siltstone-shale-carbonate facies 3. Slope environment 7] Fine clastic facies 8] Pelagic limestone facies 4. Bathyal environment 9] Dark Buchia-ammonite-lutite facies They can be seen to be organised into sedimentary cycles, which clearly show a huge transgression with three peaks in the Upper Jurassic reaching a maximum at the top of the Jurassic (Upper Tithonian). In the Lower and Middle Jurassic, sea-level changes fluctuated between coastal and shelf-sea environments, whereas in the Upper Jurassic, as a result of sea-floor spreading in the South Xizang Sea and the formation of fault basins, the area descended into bathyal depths. Paleogeographically, the northern part of the Plateau (i.e. the Northern Branch, or Neo-Tethys) underwent a shallowing process along with areal extension during Jurassic times, but shrank in the Early Cretaceous, whereas in the Southern Branch, during Jurassic-Early Cretaceous times, the South Xizang Sea developed a wide variety of sedimentary environments, including inner and outer shelf sea, continental slope and bathyal fault basin.

This thesis examines the use of remote sensing techniques for the investigation and monitoring of geothermal areas in the Taupo volcanic zone of New Zealand. The research and development of a helicopter-borne video thermal infrared scanner technique and associated computer image processing methods constitutes the major portion of this study. In addition, preliminary results are presented from a related shallow ground temperature study conducted to investigate diurnal, seasonal and meteorological effects on temperatures in active thermal ground and results from a precursory assessment of SPOT-l satellite multispectral imagery obtained over the Waiotapu Geothermal Field for detecting, identifying and mapping characteristic geothermal surface features are also reported. The initial conduct of two video thermal IR scanner test surveys, one using an Inframetrics 525 over portions of the Rotorua Geothermal Field, the other using a FLIR 1000A over portions of the Wairakei-Tauhara Geothermal Field, demonstrated that imagery useful for basic geothermal feature mapping could be obtained in the late summer to early autumn period. Surveying during the hours around dusk was shown to be appropriate. Experimentation established instrument operating settings and defined nominal survey parameters. The real-time video imagery format proved useful as an aid to navigation and as a check on proper instrument set-up and operation- The helicopter platform provided valuable manoeuvrability and control. The results obtained from these two initial surveys aided development of survey design and conduct methodology. The video imagery obtained with both the Inframetrics and FLIR scanners was compatible with New Zealand's PAL standard- Visual TV-VCR inspection of the IR imagery allowed easy identification of a range of natural thermal features. Identification of cultural features aided location of the thermal anomalies. The Inframetrics imagery suffered from serious banding and other minor problems. The FLIR imagery was of a generally higher quality, though it exhibited problems. The fundamental ability to digitize images from the videotapes and apply powerful computer image processing techniques to aid interpretation and analysis was demonstrated. A methodology for pre-processing and enhancing the digitized Inframetrics and FLIR images was developed. Application of these image processing techniques brought out detail unavailable in the grey-level imagery and greatly increased interpretation ability. The demonstrated success of the first two test surveys led to the conduct of the first known large-scale video thermal IR scanner surveys of geothermal fields. Most details of the first of these ate confidential (at the client's request). A complete range of geothermal features was detected and easily recognised and their distribution established thus providing a much more detailed map of the geothermal activity than was previously available. The successful results attained confirmed the survey design and conduct methodology used. The second and largest survey covered the entire Rotorua Geothermal Field (l8 km2). Imagery was obtained with both the Inframetrics and FLIR IR scanners and a visible wavelength video camera. Extensive ground control measurements were made. This comprehensive survey of geothermal activity established a baseline from which change can be monitored The survey identified large scale seepage and submerged thermal input into Lake Rotorua which may be the source of known missing chloride. The first geothermal surface feature changes were identified, thus demonstrating the usefulness of the method for monitoring change. Preliminary image temperature calibration results were obtained and a procedure for constructing visible wavelength-thermal IR composite images was developed. The positive results demonstrated by this survey have led to the helicopter-borne video thermal IR technique being adopted for major geothermal feature mapping and monitoring programmes in New Zealand. Preliminary assessment of the high spatial resolution (20m) SPOT-1 multispectral imagery of the Waiotapu Geothermal Field. showed that the larger geothermal surface features can be detected and identified on a contrast stretched, 3-band colour composite image. A shallow (≤ 1m depth) ground temperature measurement site was established in an area extending from very active to near ambient conditions. Preliminary results show that temperature variations ranging from l-19 °C can occur in the most active ground. These temperature variations exhibit a strong negative correlation with atmospheric prcss111e changes and can introduce large, unexpected inaccuracies in ground temperature measurements.

In several areas of Auckland, urban development has resulted in flooding and siltation problems that have been both difficult and expensive to manage. This study investigates the fluvial processes of runoff and sediment generation with a pastoral catchment of the Albany Basin and assesses the potential hydrological impacts of urban development with its catchment area. During the study period this catchment was on the fringe of the urban development of Auckland's North Shore. By examining the factors that control runoff and sediment generation within a pastoral catchment, site information that may be useful for controlling runoff and sediment generation within an urbanised Albany Basin is gained. To assess the impacts of urban development, streamflows and suspended sediment yields from catchments representative of three different land uses are compared: pastoral, urban construction and developed urban. Stream channel enlargement indices for a number of nearby catchments with different proportions of urban land cover are also determined and compared. The study shows significant increases in stormflows and suspended sediment yields from catchments that are either fully developed or undergoing construction for urban use. But due to the relatively dry weather experienced during the study period these results are thought to underestimate the impact of urbanising the Albany Basin. The investigation of stream channel enlargement shows that for totally urban catchments stream channel cross-sectional areas may be nearly three times those for pastoral catchments. Methods for controlling the impact of urban development on streamflows, sediment yields and channel enlargement are discussed. It is proposed that by developing techniques where by storm runoff is dispersed and stored within the considerable soil moisture storage capacity of an urban land cover, of the type planned for the Albany Basin, that a considerable reduction in stormflow and sediment generation may be achieved. The study concludes that through careful land use planning and the use of appropriate control structure the impacts of urban development may be reduced to acceptable levels.

This dissertation presents the results of research of physical and biological processes of sedimentation on the shoreface and continental shelf in Pakiri Bay, on the east coast of the Northland Peninsu1a, New Zealand. These environments comprise the subtidal portion of the Pakiri sand body. Sand bodies that are contiguous with unconsolidated sediments of coastal barriers are characteristic of the embayed east coasts of the Auckland and Northland Regions, yet little is known of their geomorphology. Existing models of shoreface and shelf sedimentation afford limited assistance because they were developed in different environments. Factors that distinguish the study area from other coasts include tectonic stability, lack of modern (non-biogenic) sediment inputs, the predominance of currents related to shoaling surface waves, and a sea level stillstand for the last 6,500 years. The model of sedimentation developed is derived from intensive field investigation of the morphology, sedimentology and ecology of the Pakiri Bay shoreface and continental shelf. Investigations of sediment transport entail interpretations of the sediments and sedimentary structures of the seabed, application of existing sediment transport models and the analysis of morphodynamic data. The geomorphology of the Pakiri sediment body is characterized by a regular pattern of morphologic components and associated sediment types. Alongshore variation in these characteristics is generally minor compared with shore normal variation. The shoreface comprises a curvilinear concave surface, that extends offshore from the alongshore bar approximately 1500 m, to water depths of about 22 n. The inner continental shelf comprises an equally curvilinear, mostly convex, surface that slopes seaward to the relatively flat middle continental shelf. Secondary morphological variations result from the presence of large-scale bedforms on the middle continental shelf and landward margin of the inner shelf. The sediments of the shoreface are fine, very well sorted quartz-feldspathic sands of 2 ø mean grain size. The inner shelf sediments grade offshore from a medium sand to very coarse sands and fine gravels (mean grain size 0.0 to 0.5 ø). In contrast the sediments of the mid shelf are very fine sands (mean grain size 2.0 to 2.5 ø), with a mud content of 5 to l0 percent. Carbonate skeletal debris, derived mostly from molluscs, comprises a significant proportion of inner and mid shelf sediments. The concentration of carbonates in the sediments increases offshore from 0 to 5 percent on the shoreface to 30 percent at the base of the inner shelf. The carbonate fraction of the sediments is size graded on the inner shelf and mid shelf in accordance with the grain size characteristics of the non-carbonate fraction. A model of the distribution and abundance of living macrobenthos (mostly of the phyla mollusca) is derived from benthos surveys in Pakiri Bay. Species that are diagnostic of high and low energy environments are characteristic of the shoreface and middle continental shelf respectively. The pattern of carbonate concentration in the sediments of the subtidal sediment body does not correlate with the pattern of modern biogenic production. Highest levels of modern shell production occur across the shoreface, whereas carbonate concentrations are greatest at the base of the inner shelf. Hypotheses are advanced to explain this dichotomy. The geomorphology of the shoreface and inner continental shelf is seen as a response to modern processes of sedimentation. Sediment transport occurs primarily in response to currents related to shoaling waves. Two process regimes are recognized. During typically calm (swe11 wave) conditions the fine sands of the shoreface may be transported landward as a result of an onshore mass transport current. During severe storm events this process may transport bed sediments landward across the inner shelf and middle continental shelf forming the characteristic sediment and morphologic patterns observed. However, during such events this onshore flow is, probably counteracted by return flows that are able to transport eroded foreshore and inshore sediments seaward Key words: Sedimentation, shoreface, continental shelf, wave dominated, carbonated sedimentation, sediment body, facies.

The soil seed bank in Agathis australis (D. Don) Lindl. (kauri) forests of northern New Zealand is quantified, and its potential role in secondary successions examined. Seed bank data from a number of kauri forest sites stratified by successional time and distance from forest edges are summarized using Detrended Correspondence Analysis (ordination) and linear regression models. A number of issues concerning secondary successions and the soil seed bank are discussed. These include: 1. The relationship between the soil seed bank and extant vegetation. 2. The nature of the soil seed bank and successional time. 3. The nature of the soil seed bank and distance from forest edges. 4. The soil seed bank, canopy gaps and gap regeneration strategies. 5. The nature of the soil seed bank and soil properties. 6. The fruiting phenology, seed rain, and soil seed bank dynamics. The forest sites ranged from 50 years to over 1,000 years old, while distance from forest edges ranged from 0.2 km to 3.5 km. Soil seed bank densities under kauri forests were 134 - 5,388 seeds m-2 with a mean density of 1,320±217 seeds m-2 which is similar to estimates reported for temperate and tropical forest sites elsewhere. The spatial distribution of seeds in the seed bank both within and between sites is highly variable. A total of 6,062 seedlings emerged from the seed bank samples. This represented 62 vascular plant species, 26 (42%) native woody, 19 (30%) native weedy, 16 (26) adventive weedy and 1 (2%) native fern. The species composition of the soil seed bank was not closely related to extant vegetation and only 11%ot canopy and 13% of understorey species were represented in the soil seed bank. Thus, 77% of extant vegetation at any given site is floristically different from that of the soil seed bank. Ordination of the data by detrended correspondence analysis (DCA) suggested that extant vegetation (canopy and understorey) and the soil seed bank contain characteristic floras. The species composition of the seed bank is variable between sites. The viable seed pool is larger under young successional forests than under older mature forests. The number of species also declined with distance from forest edges. Adventive and native weedy species were found in seed banks under mature forests and sites of considerable distances from forest edges. However, the density of the weedy species component of the soil seed bank was at least partly determined by distance from forest edges where such species are common. While buried seed is likely to contribute to the early stages of secondary succession, evidence from canopy gaps suggested that the seedling bank (formerly suppressed understorey component) is more important in gap regeneration than the soil seed bank. DCA analysis revealed that seedling bank species composition of canopy gaps and forest sites were quite different from the soil seed banks, indicating that regeneration stemmed from formerly (suppressed) understorey seedlings. Phenology and seed rain study of a mature forest remnant and a regenerating forest community showed that as little as 5% of the seed input to the forest floor enters the soil seed bank and remains viable for more than one year. Evidence is presented to suggest that in a forest community, secondary succession after large-scale or localised disturbance, is achieved more so by suppressed seedlings and recent seed rain than the soil seed bank. The soil seed bank becomes significant in secondary succession when the subsoil is disturbed by the uprooting of trees or the forest floor is exposed by tree-fall (not covered by tree-fall debris).

The potential of hyperspectral proximal sensing to quantify sward characteristics important in making critical decisions on the management of sheep and dairy pastures in New Zealand has been investigated. Hyperspectral data were acquired using an ASD FieldSpec® Pro FR spectroradiometer attached to the Canopy Pasture Probe (CAPP). The CAPP was developed to enable the collection of in situ reflectance data from New Zealand pasture canopies independent of ambient light conditions. A matt white ceramic tile was selected as a reflectance standard to be used with the CAPP, after testing a variety of materials. Pasture reflectance factor spectra between 350-2500 nm (with spectral resolutions of 3 nm between 350-1000 nm and 10 nm between 1000-2500 nm) and pasture samples were collected from six hill country and lowland areas, across all seasons (August 2006 to September 2007) in a number of regions in the North Island of New Zealand. After pre-processing (e.g. spectral averaging, de-stepping, elimination of noisy wavelengths, smoothing) the spectral data collected from sites were correlated against pasture botanical composition (expressed as proportions of grass, legume and weed) and pasture nutrients (nitrogen, phosphorus, potassium, calcium, magnesium, sodium and sulphur) expressed in percentage of dry matter (%) and amount (kg ha-1) using partial least squares regressions (PLSR). The accuracy and precision of the calibrations were tested using either the full cross-validation leave-one-out method or testing datasets. Regressions were carried out using the reflectance factor data per se and after mathematical transformation, including first derivative, absorbance and continuum-removed spectra. Overall best results were obtained using the first derivative data. The quality of predictions varied greatly with the pasture attribute, site and season. Some reasonable results were achieved for the prediction of pasture grass and legume proportions when analysing samples collected during autumn (grass: R2 > 0.81 and SD/RMSEP 2.3 and legume: R2 > 0.80 and SD/RMSEP 2.2), but predicting pasture weed content was poor for all sites and seasons (R2 = 0.44 and SD/RMSEP = 1.2). The inaccurate predictions might be explained by the fact that the diversity found in the field and observed in the pasture spectral data was not taken into account in the pasture botanical separation. The potential for using proximal sensing techniques to predict pasture nutrients in situ was confirmed, with the sensing of pasture N, P and K increased by the procedure of separating the data according to the season of the year. The full potential of the technology will only be realised if a substantial dataset representing all the variability found in the field is gathered. The importance of obtaining representative datasets that embrace all the biophysical factors (e.g. pasture type, canopy structure) likely to affect the relat ionship, when building prediction calibrations, was highlighted in this research by the variance in the predictions for the same nutrient using different datasets, and by the inconsistency in the number of common wavelengths when examining the wavelengths contributing to the relationship. The ability to use a single model to predict multiple nutrients, or indeed individual nutrients, will only come through a good understanding of the factors likely to influence any calibration function. It has been demonstrated in this research that reasonably accurate and precise pasture nutrient predictions (R2 > 0.74 and SD/RMSEP 2.0) can be made from fresh in situ canopy measurements. This still falls short of the quality of the predictions reported for near infrared reflectance spectroscopy (NIRS) for dried, ground samples analysed under controlled laboratory conditions

This thesis demonstrates some of the potential of Libocedrus bidwillii Hook. f. (Kaikawaka) for dendroclimatological research by developing tree-ring chronologies and then using these chronologies to reconstruct palaeoclimates. In order to assist with the modelling of tree-growth and climate relationships (response function analysis), the annual nature of Libocedrus bidwillii growth was investigated. Results showed that seedlings of Libocedrus bidwillii were sensitive to temperature and soil moisture. Greatest growth was at high soil moisture and under a variable temperature regime. It was also found that there was an obvious seasonal variation in the growth of the seedlings. Such information allowed some confidence in the use of the species as a proxy-climatic indicator. Twenty-three tree-ring chronologies were developed from different areas of New Zealand. These included 12 new sites, 5 sites collected by other people but then updated and 6 sites that were not updated. Standardisation of the tree-ring series from each site used double detrending methods - ERH+SP67% (linear-Exponential or linear Regression or a Horizontal detrending plus SPline detrending fitted to 2/3 the length of the tree-ring series). This meant some long-term trends in the data were retained (i. e. greater than 120 year cycles) although this led to some reduction of the strength of the common signal in the chronology as measured by EPS (Expressed Population Signal) and SNR (Signal of Noise Ratio). The retention of long-term trends in the chronologies was thought to be important because some low frequency signals, which are longer than 120 years, are present in the climate data. Autocorrelation in the chronologies was removed by the ARSTAN program using the Aikaike Information Criterion (AIC) to determine the filter model. No significant autocorrelations were left in the residual chronologies produced by this method. Inter-comparison of the chronologies showed a highly consistent and significant pattern between most of the sites. There was little reduction in inter-chronology correlation with separation distance. However, there was a difference, or an effect, due to altitude. In general the response functions for the relationship between climate variables and ring-width in any given growing season showed a negative relationship between temperature for the prior growth months February, March and current December, while there was a positive response to temperature in September and February. There were three significant negative coefficients (previous March, April and August) and one positive (current February) for precipitation. The results of using principal component analysis (PCA) showed that all the 27 significant response function analyses could be divided into four groups. The response pattern in the four groups was similar for temperature but the rainfall response was more variable. The climate reconstructions were based on two groups of chronologies: eleven chronologies from all over New Zealand and a subset of only the three longest chronologies. Comparison of the climate data of different seasons with the two groups of chronologies was carried out using the "bootstrap" transfer function. The average February-March temperature and total March-April precipitation were finally selected as the reconstructed variables. Both of the groups reconstructed the hot years better than the cold years. The reconstructed temperature series were similar to all the earlier New Zealand dendroclimatic reconstructions. The warming and cooling periods, extremely warm and extremely cold years were identified and compared with some other sources of evidence and found to be highly consistent. This led to the conclusion that Libocedrus bidwillii is very useful as a high resolution palaeotemperature indicator. In the precipitation reconstruction, all the periodicities (both high and low) in the observed data were reconstructed. The dry and wet periods, severe drought and very wet years were identified in both precipitation reconstructions and also compared with other more limited sources of evidence.

Popular geography magazines like National Geographic (NG) provide readers with a lens of the world around them. Yet sadly they often only serve a limited utilitarian purpose as dust collectors on coffee tables of hospital waiting rooms or doctors’ practices. It should be of little surprise then that the relative importance of geographic magazines as a representational forum has been underestimated historically. The importance of geographic magazines as an outlet for creating and disseminating preconceived visions of what may be termed ‘popular geographies’ has only become the subject of scrutiny in the last two decades. Authors including Lutz and Collins (1993) and Rothenberg (1994, 2007) have reflected critically upon the place of NG as a powerful ideological institution for legitimating particular visions of the world in the wider corpus of the discipline of geography. Yet while there has been a substantial volume of work dedicated to unravelling the situated lens of NG there has been no research devoted to deciphering the lenses of other geography magazines such as Canadian Geographic (CG), Australian Geographic (AG) or New Zealand Geographic (NZG). These magazines also embody the ideals of adventure, discovery and nature made famous by NG but purvey geography through distinctively national narratives. Through discourse analysis the thesis examines these three magazines in order to unravel geographic imaginations of nationalism in CG, AG and NZG and in the process challenge divergent conceptions of geography itself as both an academic discipline and popular subject.

The present work is a contribution to description and understanding of the distribution and movement of water in swelling soils. In order to investigate the moisture distribution in swelling soils a detailed knowledge of volume change properties, flow characteristics and total potential of water in the soil is essential. Therefore, a possible volume change mechanism is first described by dividing the swelling soils into four categories and volume change of a swelling soil is measured under different overburden pressures. The measured and calculated (from volume change data) overburden potential components are used to check the validity of the derivation of a load factor, ∝. Moisture diffusivity in swelling soil under different overburden pressures is measured using Gardner's (1956) outflow method. Behaviour of equilibrium moisture profiles in swelling soils is theoretically explained, solving the differential equation by considering the physical variation of individual soil properties with moisture content and overburden pressure. Using the measured volume change data and moisture potentials under various overburden pressures, the behaviour of possible moisture profiles are described at equilibrium and under steady vertical flows in swelling soils. It is shown that high overburden pressures lead to soil water behaviour quite different from any previously reported.

Charwell Basin is a 6 km-wide structural depression situated at the boundary between the axial ranges and faulted and folded Marlborough Fault Zone of north-eastern South Island, New Zealand. The basin contains the piedmont reach of the Charwell River, and a series of late Quaternary loess-mantled alluvial terraces and terrace remnants that have been uplifted and translocated from their sediment source due to strike-slip motion along the Hope Fault which bounds the basin to its immediate north. The aim of this study was to provide an interdisciplinary, integrated and holistic analysis of late Quaternary landscape evolution and environmental change in Charwell Basin using terrain analysis, loess stratigraphy, soil chemistry and paleoecological data. The study contributes new understanding of New Zealand landscape and ecosystem responses to regional and global climatic change extending to Marine Isotope Stage (MIS) 6, and shows that climatically-forced shifts in biogeomorphic processes play a significant role in lowland landscape evolution. Morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time, with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo-concave land elements. Paleotopographic analysis of a >150 ka terrace mantled by up to three loess sheets revealed multiple episodes of alluvial aggradation and degradation and, subsequent to river abandonment, gully incision prior to and coeval with loess accumulation. Spatial heterogeneity in loess sheet preservation showed a complex history of loess accumulation and erosion. A critical profile curvature range of -0.005 to -0.014 (d²z/dx², m⁻¹) for loess erosion derived from a model parameterised in different ways successfully predicted loess occurrence on adjacent slope elements, but incorrectly predicted loess occurrence on an older terrace remnant from which all loess has been eroded. Future analyses incorporating planform curvature, regolith erosivity and other landform parameters may improve identification of thresholds controlling loess occurrence in Charwell Basin and in other South Island landscapes. A loess chronostratigraphic framework was developed for, and pedogenic phases identified in, the three loess sheets mantling the >150 ka terrace. Except for one age, infrared-stimulated luminescence dates from both an upbuilding interfluve loess exposure and colluvial gully infill underestimated loess age with respect to the widespread Kawakawa/Oruanui Tephra (KOT; 27,097 ± 957 cal. yr BP), highlighting the need for improvements in the methodology. Onset of loess sheet 1 accumulation started at ca. 50 ka, with a break at ca. 27 ka corresponding to the extended Last Glacial Maximum (eLGM) interstadial identified elsewhere in New Zealand. Loess accumulation through MIS 3 indicates a regional loess flux, and that glaciation was not a necessary condition for loess generation in South Island. Loess accumulation and local alluvial aggradation are decoupled: the youngest aggradation event only covers ~12 kyr of the period of loess sheet 1 accumulation. Older local aggradation episodes could not be the source because their associated terraces are mantled by loess sheet 1. In the absence of numerical ages, the timing of L2 and L3 accumulation is inferred on the basis of an offshore clastic sediment record. The upbuilding phase of loess sheet 2 occurred in late MIS 5a/MIS 4, and loess sheet 3 accumulated in two phases in MIS 5b and late MIS 6. Biogenic silica data were used to reconstruct broad shifts in vegetation and changes in gully soil saturation status. During interglacial/interstadial periods (MIS 1, early MIS 3, MIS 5) Nothofagus-dominated forest covered the area in association with Microlaena spp grasses. Lowering of treeline altitude during glacial/stadial periods (MIS 2, MIS 3, MIS 5b, late MIS 6) led to reduction in forest cover and a mosaic of shrubs and Chionochloa spp, Festuca spp and Poa spp tussock grasses. Comparison of interfluve and gully records showed spatial heterogeneity in vegetation cover possibly related to environmental gradients of exposure or soil moisture. A post-KOT peak in gully tree phytoliths corresponds to the eLGM interstadial, and a shift to grass-dominated vegetation occurred during the LGM sensu stricto. Diatoms indicated the site became considerably wetter from ca. 36 ka, with peak wetness at ca. 30, 25 and 21 ka, possibly due to reduced evapotranspiration and/or increased precipitation from a combination of strengthened westerly winds and increased cloudiness, or strengthened southerly flow and increased precipitation. Human influence after ca. 750 yr BP led to re-establishment of grassland in the area, which deposited phytoliths mixed to 30 cm depth in the soil. A coupled gully colluvial infilling/vegetation record showed that sediment flux during the late Pleistocene was ~0.0019 m³ m⁻¹ yr⁻¹ under a shrubland/grassland mosaic, and Holocene sediment flux was ~0.0034 m³ m⁻¹ yr⁻¹ under forest. This increase of 60% through the last glacial-interglacial transition resulted from increased bioturbation and down-slope soil transport via root growth and treethrow, which formed a biomantle as evidenced by slope redistribution of the KOT. These results contrast with sediment transport rates and processes hypothesised to occur contemporaneously in adjacent mountain catchments. This suggests that intraregional biogeomorphic processes can differ significantly depending on topography and geological substrate, with different landscapes responding in unique ways to the same climate shifts. Analysis of Quaternary terrestrial landscape evolution in non-glaciated mountainous and lowland areas must therefore consider spatial and temporal heterogeneity in sediment fluxes and underlying transport processes.

The disposal of waste from agricultural activities has been recognised as a source of environmental contamination by endocrine disrupting chemicals (EDCs). The New Zealand dairy industry produces a large volume of dairy farm effluent, which contains EDCs in the form of estrogens. Most of this dairy farm effluent is applied onto the land for disposal. Groundwater and soil contamination by estrogens following waste application on the land have been reported overseas, but our understanding of the processes and factors governing the fate of estrogens in the soil is poor. Therefore the main goal of the present study was to better understand the fate and transport of estrogens, in particular 17β-estradiol (E2) and estrone (E1) in soil. In order to quantify E1 and E2 in drainage water and soil samples, chemical analysis by gas-chromatography mass-spectrometry (GC-MS) was carried out. This included sample extraction, sample clean-up through silica gel and gel permeation chromatography, and sample extract derivatisation prior to analysis. In order to develop a reliable method to extract estrogens from soil, research was conducted to optimise E1 and E2 extraction conditions by adjusting the number of sonication and shaking events, as well as the volume and type of solvent. Among five solvents and solvent mixtures tested, the best recovery on spiked and aged soil was obtained using an isopropanol/water (1:1) mix. A microcosm experiment was carried out to determine the dissipation rates of E2 and E1, at 8°C and at field capacity, in the Templeton soil sampled at two different depths (5-10 cm and 30-35 cm). The dissipation rates decreased with time and half-life values of 0.6-0.8 d for E1 and 0.3-0.4 d for E2 were found for the two depths studied. A field transport experiment was also carried out in winter, over three months, by applying dairy farm effluent spiked with estrogens onto undisturbed Templeton soil lysimeters (50 cm in diameter and 70 cm deep). The hormones were applied in dairy farm effluent at 120 mg m⁻² for E2 and 137 mg m⁻² for E1. The results of the transport experiment showed that in the presence of preferential/macropore flow pathways 0.3-0.7% of E2 and 8-13% of E1 was recovered in the leachate at the bottom of the lysimeters after 3 months, and 1-7% of the recovered E2 and 3-54% of the recovered E1 was leached within 2 days of application. These results suggest that leaching of estrogens via preferential/macropore flow pathways is the greatest concern for groundwater contamination. In the absence of preferential/macropore flow pathways, a significant amount (> 99.94%) of both hormones dissipated in the top 70 cm of soil, due to sorption and rapid biodegradation. Surprisingly, in all cases, estrogen breakthrough occurred before that of an inert tracer (bromide). This could not be explained by the advection-dispersion transport of estrogens, nor by their presence as antecedent concentrations in the soil. It was therefore suggested that colloidal enhanced transport of estrogens was responsible for the earlier breakthrough of estrogens and caused the leaching of a fraction of the applied estrogens to a soil depth of 70 cm. A two-phase model, adapted from a state-space mixing cell model, was built to describe the observed estrogen transport processes under transient flow. The model takes into account 3 transport processes namely, advection-dispersion, preferential/macropore flow and colloidal enhanced transport. This model was able to successfully describe the estrogen transport observed from the lysimeters.

This thesis describes the vegetation and climatic changes over the past 20,000 years from pollen records at eight northern New Zealand lowland peat and lake sites, ranging from Taranaki to the Far North. The sites investigated are Umutekai Swamp (Taranaki), Lakes Rotomanuka, Rotokauri, and Okoroire (Waikato), Kopouatai Bog (Hauraki Plains), Lake Waiatarua (Auckland), Otakairangi Swamp (mid-Northland), and Trig Road Swamp (Far North). At sites from Auckland southwards, dating and correlation of the pollen records were enhanced by the occurrence of multiple tephra layers within the pollen-bearing sediments. The clearest picture of regional vegetation history and tightest chronologic control were obtained from the tephra-rich organic lake sediments of the Waikato lowlands. Holocene vegetation changes were broadly consistent throughout this northern New Zealand region and indicate climates, which were initially moist, mild and equable, but became increasingly variable and probably drier overall during the late Holocene. Podocarpangiosperm forest was always prominent and Agathis australis forest expanded throughout the region north of latitude 38° S during the last 6,000 years. Kauri was especially prominent in the Waikato region during the 1000 years or so following the Taupo eruption of c.1800 years ago. At pollen sites from Waikato, Hauraki Plains, and Auckland, palynological evidence suggests that people began clearing forests as early as 800 years ago, but probably not much earlier. Pollen records for the last glacial show less regional uniformity. South of Auckland, scattered tracts of Nothofagus or Libocedrus forest within a shrubland/grassland mosaic were succeeded, between c.14.5 and 10 ka by the regional expansion of podocarp-angiosperm forest, with Prumnopitys taxifolia initially prominent. North of Auckland, the pre-Holocene vegetation history is complicated by uncertain chronologies. Conifer-angiosperm forest with prominent A. austalis grew in the Far North during the last glacial, while in mid-Northland, a substantial period of Nothofagus forest, shrub and grassland communities may correspond to either the entire last glacial or to the late glacial. Local variations in vegetation cover were maintained to some extent independently of regional climate, influenced by site specific factors including edaphic controls, hydroseral succession, and local hydrological changes caused by, e.g., lahar or lava flow, fluvial activity and sea level change. The influence of these local factors is most evident for the late glacial, during which period podocarp-angiosperm forest spread throughout northern New Zealand generally, but with considerable variation in timing even between nearby sites. Fire appears to have been an important factor in vegetation change throughout the period investigated, not just during the human deforestation era; peat swamp communities show a long history of association with fire, while in dryland vegetation, Agathis australis appears to have been especially affected by burning. No unequivocal evidence was found for postglacial latitudinal migrations, but several plants show significant altitudinal range expansions during the last glacial compared with their present distributions in northern New Zealand, viz., Nothofagus menziesii, Libocedrus bidwillii, Phyllocladus aspleniifolius, and Halocarpus spp. Thus although vegetation communities at each locality have changed substantially over time, the flora of northern New Zealand remained essentially the same during the c.20,000 years before the human era. Interpretation of the pollen records was assisted by principal components analysis (PCA) and by referring to modern pollen data and pollen-vegetation comparisons obtained from Waipoua Forest, Northland. PCA provides an efficient means of summarising and portraying large pollen datasets, and helps to clarify underlying environmental factors and temporal trends. PCA also generally supports pollen diagram zonations determined by eye. The Waipoua study indicated that the relationship between pollen and tree abundances is highly variable within forests, dependent largely on local site characteristics, especially the masking effect of strong local pollen sources. Nevertheless, quantified pollen-vegetation relationships averaged for the study area mostly accord with results from previous New Zealand modern pollen rain studies, while adding new information for the pollen representation of several prominent northern species. The Waipoua study indicates that pollen spectra rich in Agathis may be found where trees grow nearby, but Agathis pollen appears to be less widely dispersed than pollen of other New Zealand anemophilous taxa. At several swamp sites, correlation of tephra layers and pollen-stratigraphic events reveals problems with radiocarbon chronologies which can not be satisfactorily resolved except by assuming contamination by modern carbon. Sites with a history of hydroseral succession, where swamp communities have developed in former lake basins, are especially prone to this contamination, presumably because root penetration of older sediments provides channels for downward movement of younger carbon. In such situations it may be unwise to date and correlate pre-Holocene sediments on the basis of radiocarbon alone. Periods of hiatus are not uncommon in lake and swamp profiles from northern New Zealand and it is possible that the record of the last glacial is missing or strongly compressed at many Northland sites. Sedimentation rates also varied markedly between and within sequences, precluding the accurate estimation of pollen accumulation rates except at the Waikato lake sites where tephra sequences provide detailed chronological resolution. Even here, however, pollen concentration and accumulation rates appear to have been highly susceptible to short-term fluctuations in the sedimentation regime.

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This thesis describes the facies, architecture and development of the Tunanui Formation, a deep-marine, sand-rich, slope basin-fill of Middle Miocene age (NZ stages Clifdenian to Lillburnian). The study area is located in the northern Hawke Bay region of the East Coast Basin, North Island, New Zealand, and is within the forearc domain of the Hikurangi active margin. It is part of a structurally complex and now largely emergent accretionary wedge with sediments dating from basal Miocene to present. Due to renewed plate subduction and compressive movements along the margin in the Neogene, highly restricted intra-slope basins developed between rising thrust ridges of the inner-forearc. The Tunanui deepwater-clastics were originally deposited as flat-lying sediments within one such elongate slope-basin, atop the deformed sedimentary prism. These rocks are now present within the subsurface of offshore Hawke Bay and extend N/NW to the onshore areas. Structural inversion has produced outcrops of Tunanui sediments in the core of two major anticlines, the Mangaone and the Morere Highs. In the Morere Anticline along the Paritu Coast south of Gisborne, spectacular sea-cliff exposures provide a unique opportunity to investigate the nature and development of over 1000 m thickness of sandy, deepwater, slope basin-fill representing almost the entire stratigraphic section of the Tunanui Formation. Rocks in this remote region have not been previously described in any detail. A database of thousands of digital field photographs, together with 71 stratigraphic logs and some deep borehole information has enabled the production of a series of detailed correlations for the Tunanui sections. In turn, the number of logs available has made possible the construction of a large-scale (over c.25 km in length) stratigraphic cross-section, slightly oblique to the basin axis, through the deepwater clastic succession. Interpretation has allowed a series of deductions to be made concerning the nature of the 'Tunanui Basin' fill and its development, the types of gravity flow elements present and in most field areas, the production of a detailed sandstone architecture for the Tunanui deposits. Five phases of basin fill are recognised. These range from highly restricted, over-thickened sandstone packages, deposited under conditions of high slope gradient and complex basin-floor topography, within the lower parts of the sequence, to laterally continuous 'fan-like' deposits, and thinner-bedded sandstones within the upper part of the Tunanui section. A c.250 m thick sequence that is slightly younger than the upper Tunanui Formation, containing numerous channel-forms (the Tangawa Formation), is present on the East Coast of the Mahia Peninsula c.17 km to the south of the Paritu Coast outcrops. The architecture of the Tangawa Formation, and its regional structural position, indicates that it was the 'spill' of the Tunanui basin-fill into an adjacent down-slope sediment trap within the forearc terrane. This depocentre was also controlled by deep-seated imbricate thrust faulting in common with the Tunanui Basin. Several different types of deepwater channel-forms are present within what is a limited stratigraphic range. The vertical sequence reflects an overall progression within a muddy slope from deeply incised, erosive systems, to laterally offset-stacked channels of a mixed erosional depositional type.

The Ngawha geothermal system is the only known high temperature (220-230˚C) system in New Zealand outside the Taupo Volcanic Zone. This current examination integrates new and available geochemical and geological data on the system and surroundings. Ngawha occurs in a Quaternary-Holocene basalt field, within a ENE-trending extensional fault block 15 km in width. The youngest volcanism in the region is associated with this structure. The basaltic activity changed in composition from earlier (? 1.5 to 0.5 m.y.) high-Al, to younger alkali basalt (< 0.5 m.y. to at least 1200 yr b.p.). Crystal fractionation of the alkali basalt magma produced comenditic rhyolite lava, which outcrops as a dome near Ngawha, and is also inferred to have formed an unerupted intrusion, the likely heat source. The geothermal system has developed within pre-existing fault/fracture permeability in basement metasediments (Permian-Jurassic greywacke and argillite), and is concluded to be on the order of 10,000-20,000 years old. The hydrological model developed for the system is of a fault-bounded reservoir within basement rocks, formed of a series of blocks within which fluid migrates in fractures and joints. The reservoir has a low permeability base from silica deposition, and fluid is confined by a caprock of 500-700 m of Cretaceous-Tertiary marine sediments. This allows only vapour discharge at the surface, and minor local leakage of reservoir waters. Recharge to the system is indicated to occur from the N-NE, with subsurface discharge from the reservoir to the SW. Recharging waters are heated during deep circulation (? 3.5 km) and enter the reservoir from faults to the N and on the southern boundary. Vertical displacement of up to 100 m occurs on some of these faults. Most of the 15 wells drilled (usually 1000-1200 m deep) are within the reservoir. The reservoir fluids are slightly acid pH (5.6 at 230˚C) alkali C1 type, but contain high B (800 mg/kg) and NH3 (200 mg/kg). They have a high gas content, largely CO2 (1.2 wt %) and H2S (100 mg/kg). These fluids have ascended in boundary faults, "degassing" during ascent, with the greatest vapour separation in the upper part of the reservoir. The residual fluids then enter the reservoir. Most dissolved constituents are probably derived from high temperature (? 350ºC) leaching of metasediments at depth below the reservoir. Some, however, also have a magmatic component (CO2, S(H2S), N2(NH3), Hg). The fluids have elevated б18O values (+ 5.5 ‰) relative to local meteoric water (-5.5‰), but reservoir rocks have only been depleted c. 1‰. It is concluded the high б18O is derived from rock leaching at depth, a magmatic component and boiling enrichment during fluid ascent. Reassessment of the hydrothermal mineralogy and oxygen isotopes in quartz, show that the system previously contained 260º-280ºC fluids. Tectonic (fault) movement resulted in an inflow of cooler groundwater from the E "flooding" part of the reservoir and reducing temperatures to c. 180ºC. continued inflow of hot water from the N and S, and heat in rocks, has reheated the reservoir to the current measured temperatures (c. 230ºC). The onset of the cool inflow was probably only several thousands of years ago, and it has persisted and produced a zone of fluid mixing across the central part of the reservoir. This inflow can be identified by oxygen and carbon isotopes (in quartz and calcite), fluid chemistry, alteration minerals, and major and trace element chemistry of rocks, as well as downhole temperatures. Temperature inversions have resulted in some parts. The distribution of major, and twenty-six trace elements, was examined in cores and cuttings from twelve geothermal wells, and compared to equivalent non-geothermal lithologies. Distribution was also related to temperature, permeability and mineralogy. Most major elements have been added to reservoir rocks, but there is obvious depletion of K and Al. Of trace elements, Ba, Rb and Th are strongly depleted. Most trace elements typically show trends of major elements with which they are associated, usually by ionic substitution (e.g. Ca-Sr; K-Rb). Zn, for example, is strongly associated with Fe-and Mg-bearing alteration minerals. Some elements can be correlated with temperature, such as increasing Li, Cd, S, Ca, La and Mg. Base metals are typically enriched 30-50% relative to non-geothermal samples. Element associations, are however, often hard to determine due to the limited distribution of alteration (very low water/rock ratios), the occurrence of elements in different mineral phases, and the episodic deposition of hydrothermal minerals. The basement rocks (Waipapa Group) are of quartzo-felds-pathic nature, but have a minor volcanic contribution. Ratios of immobile trace elements (La/V vs Y) appear to be useful in distinguishing whether geothermal samples are greywacke or argillite. Sulphur fugacities of Ngawha fluids are low and S-bearing minerals are not abundant. Sulphide minerals are of limited occurrence, pyrite being the main sulphide (< 5% of rocks) with minor amounts of poorly crystalline pyrrhotite. Both are more common in the upper reservoir-lower caprock, a zone in which boiling occurs. Pyrite is often of earlier (hotter) formation, and pyrrhotite of the recent-current regime. Pyrrhotite is typically monoclinic or monoclinic + hexagonal. Minor arsenopyrite was found locally in a fault intersection; traces of sphalerite and chalcopyrite have been identified. Minor S as a sublimate forms veins at the surface, but hydrothermal SO4 minerals are in trace amounts only. Grains of primary (detrital) barite were identified in metasediments. Minor amounts of As and Sb sulphides occur at the surface in the main thermal zone. Within that area Hg was previously mined both as cinnabar in siliceous lenses, and adsorbed Hg˚ in fine grain sediments. Mercury is transported through the system as Hg˚ vapour. Downhole analyses of cuttings (30-50 m intervals) show Hg has not been leached from rocks in the reservoir, and is stable in pyrite at that temperature range (200˚-250˚C). The decrease of temperatures in the caprock (<150˚C) allows adsorbed Hg˚ to become stable and deposit. Gold and Ag are in low concentration in all geothermal rocks, the highest being Au = 0.07 ppm and Ag = 0.55 ppm. Gold is mostly associated with pyrite and concentrations are higher in the hot inflow zones; it is depleted in the cool inflow, presumably by subsequent dissolution. Silver occurs in pyrite, but also as other phases not identified (possibly in pyrrhotite), and is enriched in the cool inflow. Well discharge silica has relatively elevated concentrations (Au = 0.27, Ag = 13.9 ppm) and is considered analagous to sinter deposits that would form in the absence of a caprock. Sinters forming to the N of the thermal area, contain very low metallic trace elements, as they form from neutral pH HCO3 waters in the caprock. Modelling the hydrology of the overall system and using Au bisulphide solubilities suggests the likelihood that Au (and base metals) have deposited from the fluids in upflow zones before they enter the reservoir. This model appears to be supported by greater mineralisation in well Ng5 samples, in the N of the drillfield.

The active Orakeikorako-Te Kopia geothermal system was drilled in the mid-1960’s, down to 1405m, as part of a programme to investigate its electrical generation capability. Four wells were completed at Orakeikorako (23km NNE of Taupo) and two at Te Kopia, 9.5km further northeast. The exploration drilling provided information on the present day hydrological and thermal regime which is as hot as 265°C (1137m drilled depth (-801m RL) in OK-2). Major flows into the wells occurred at depths down to 850m, although poor permeability and decline in mass output discouraged development. The waters discharged were of near neutral pH and had low salinities (highest Cl content from OK-2 ≈546mg/kg), low discharge enthalpies and indicated water temperatures (TSiO2 and TNaKCa) of 2l0°C to 240°C. A hydrologic model proposed here envisages a hot water reservoir in the OK-2 area (northeastern part of the Orakeikorako thermal area) with a lateral flow supplying water to the Red Hill (OK-4 area) in the southern part of the system and a concealed northeast flow which reaches the surface at Te Kopia. The Orakeikorako thermal area occupies a surface area of about 1.8km2, mainly on the east bank of the Waikato River, where dilute chloride-bicarbonate water discharges along faults and fractures in association with an extensive silica sinter sheet, boiling springs and geysers. The occurrence of a mordenite-smectite assemblage at shallow depths, plus the oxygen and hydrogen isotopic composition of surface discharge waters, indicate that the ascending chloride fluids are diluted by near surface (heated?) groundwaters. The δD shift from local groundwater composition may be evidence for a magmatic component to the convecting hydrothermal system. Incursion of fluids from the relatively cool (300°C to ~250°C as it ascended, resulting in the deposition of adularia, quartz and bladed calcite. The system has cooled, resulting in lower subsurface temperatures (as recorded by fluid inclusion geothermometry) suppressing boiling, and migrated northwards as a consequence of self sealing. The thermal decline and retention of CO2 in the deep alkali-chloride fluid shifted the alteration assemblage from one of albite-adularia stability to illite stability. The homogenisation (Th) temperatures of primary and secondary liquid-rich inclusions in 27 cores from different depths mostly match measured temperature profiles (e.g. OK-1 (shallow levels) and OK-2). Never-the-less, fluid inclusion data support mineral-inferred stability temperatures which indicate that parts of the Orakeikorako-Te Kopia system have cooled appreciably (e.g. OK-1, deep levels) and OK-4 (maximum Tbore=238°C, maximum Th=312°C; epidote abundant). In contrast, the northwestern margin (OK-6 area) has heated (OK-6:1113.4m; Tbore=261°C, Th=210-221°C). Some inclusions in the Te Kopia drillholes have Th values that exceed Tbore by as much as 50°C, and are deduced to have been uplifted by movement on the Paeroa Fault. Freezing data indicate that the trapped fluid was dilute (~0.2 to 1.7 wt% NaCl equivalent) since most Tm values range from -0.1 to -0.5°C. The outflow portion of the Orakeikorako-Te Kopia system has evolved recently, both chemically and physically. Movement on the Paeroa Fault, that uplifted pyroclastic rocks hosting a quartz-adularia-illite assemblage, combined with a lowering of the watertable has resulted in an overprinting of the neutral pH hydrothermal mineral assemblage by a kaolinite-alunite type assemblage which derives from an acid sulphate fluid. Quartz crystals found 150m above the base of the Paeroa Fault scarp host dilute (~1.5wt% NaCl equivalent) fluid inclusions with Th values that range from 180-206°C (average 196°C). Bladed quartz (after calcite) did not contain usable inclusions. It is deduced that the inclusions formed about 120-160m below the ground, which indicates uplift in the order of ~300m. Assuming a constant rate of uplift of 4m/ka (based on the offset of 330ka Paeroa Ignimbrite), the minimum duration of activity at Te Kopia is 75,000 years.

The Karikari Plutonics are Early Miocene in age and consist of two plutonic bodies, with age relations delineated by cross- cutting relationships, and associated later stage dykes. The older pluton is a complex body exhibiting textural variability, cumulate-style crystallisation, varied enclaves (indicating complex magma chamber processes including convection and crystallisation along steeply-dipping northwest oriented fronts) and a multi-phase structural and dyke intrusion history. Modal analysis shows this body to be diorite to quartz monzodiorite, and geochemically calc-alkaline and medium-K in nature. In contrast the younger pluton is extremely homogeneous and intruded by a single, volumetrically sparse, dyke phase. Modally quartz monzonite to granite (adamellite), and high-K calc- alkaline, this body has higher Si, K-group + Na, REE group and HFSE group elements than the older pluton. Mineral differences are confined to An contents in plagioclase, En values in orthopyroxenes and a wider range of Al in younger pluton hornblendes. Igneous differentiation can be modelled within the older pluton and between the older and younger bodies, by fractional crystallisation dominated by plagioclase, with subordinate ortho- and clino- pyroxene and oxide phases. The dykes show a compositional range from basaltic andesite to dacite, with andesite volumetrically dominant. A temporal trend can be seen with younger dykes becoming more felsic and of greater volume, and changing orientation from northeast to northwest. Two subdivisions can be made based on the presence or absence of hornblende. Pyroxene only dykes are mostly medium-K and dominantly andesitic, whereas hornblende-bearing lithologies are both medium-K and high-K, are andesite and dacite, and appear to be more evolved chemically. The rock envelope into which the Karikari Plutonics was intruded consists of Cretaceousage basalts, rhyolites and sedimentary lithologies. Although a regular contact aureole is not exposed, the lowest grade of contact metamorphism is delineated by the first occurrence of biotite. Rocks equivalent to the hornblende hornfels facies are widespread and rare pyroxene hornfels are found adjacent to contacts. Alteration and veining, particularly prevalent in fault/shear zones, and the presence of a magmatic-hydrothermal type breccia are evidence for a hydrothermal system associated with the waning stages of Lower Miocene-age igneous activity on the Karikari Peninsula. Fluid inclusion and stable isotope data indicates the presence of fluids of both magmatic and meteoric origin. The Karikari Plutonics are correlated with the arc-type regional association of Northland and the Coromandel Peninsula. The source of these rocks is broadly M-type, hydrous and involving subduction zone, and modified mantle wedge components, but with some unspecified crustal involvement indicated by Sr isotopes. Specifically this source is modelled, for the Karikari Plutonics, as having LREE enriched 2x relative to HREE and partially melting (< 15% of the source) at the base of the crust (≥30 km). These melts gave rise to the arc-type association either erupting at the surface, or ponding in upper crustal (≤10 km) magma chambers.

The stratigraphic record of lahars in the Whangaehu River reveals that in the past 180,000 years this route has been one of the main conduits for lahars from Mount Ruapehu, the highest active andesitic stratovolcano in the Central North Island of New Zealand. Both debris flows and hyperconcentrated flows have engulfed surfaces up to 160 km distance from the Volcano. Eight episodes of laharic activity are recognized by the distinctive lithology and similar age of their deposits. The newly defined upper Pleistocene Whangaehu Formation provides evidence for the earliest lahar event in the Valley, c. 180,000- 140,000 years ago. There is only meagre evidence for laharic activity following this event until the Ohakean and Holocene, although two new informally named deposits - the Mangatipona pumice sand (c. 37,000 years B.P.) and Apitian lahars (c. 32,000-25,500 years B.P) - are recognized, of minor extent. The formerly defined late Quaternary Te Heuheu (c. 25,500- 14,700 years B.P.), Tangatu (c. 14,700-5,370 years B.P.), Manutahi (c. 5 ,370-3,4600 years B.P.), Mangaio (c. 4,600 years B.P.) and Onetapu (< c. 1,850 years B.P.) Formations are here described and interpreted. Triggering mechanisms for lahar deposits are distinguished based on lithological criteria. (a) Bouldery deposits in the Whangaehu Formation are interpreted to have been emplaced by a single highly competent debris flow triggered by a southerly-directed flank collapse at Mount Ruapehu. This debris flow was competent enough to transport boulders up to 2 m in diameter over 140 km from the Volcano. Bouldery deposits are also recognized in the Onetapu Formation, but are restricted to higher gradient surfaces on the Mount Ruapehu ring plain. The Onetapu Formation deposits are interpreted to have been emplaced by lahars resulting from catastrophic drainage of Crater Lake, which occupies the active crater on Mount Ruapehu. (b) Pebbly and sandy deposits are interpreted to have been emplaced by low competence debris flows and hyperconcentrated flows. These lahar deposits are recognized in all formations described. The lithology in these deposits is commonly pumice and they are interpreted to have been triggered by eruptions and/or high rainfall events at the Volcano. Formations, and individual members within Formations, were dated by radiocarbon dating of organic material found below, within or above lahar deposits, or by coverbed stratigraphy. Both rhyolitic and andesitic tephras provided recognizable time planes in the late Quaternary coverbeds overlying lahar deposits. In this study quantitative analysis of quartz abundance, which is shown to vary between loesses and palaeosols, is used as an indirect means of establishing a surrogate for past climate changes which have been correlated to the deep sea oxygen isotope curve. A minimum age for the newly defined Whangaehu Formation is established by this method. The accumulation rate for lahars in the Whangaehu River has accelerated from 1 km3 every c. 23,000 years in the past c. 160,000 years to 1 km3 in 589 years in the past c. 2,000 years. This acceleration probably results from the increased frequency of lahars in the River following the development of Crater Lake c. 2,000 years B.P. According to this pattern an estimated 0.17 km3 volume of lahars could be anticipated over the next 100 years. If the 2,000 year accumulation rate were to be met over the next 100 years there would be 170 lahars of l0[superscript]6 m3 in this time interval , or 17 lahars of 10[superscript]7 m3 (or 1.7 lahars of 10[superscript]8 m3). The largest reported volume for an historic lahar is 10[superscript]6 m3 and these have occurred on average once every 30 years. The accumulation rate for historic lahars is 0.0054 km3 in 100 years. Therefore, although the accumulation rate appears to have slowed down, further large lahars with magnitudes 10 or 100 times greater than those witnessed could be expected.

The Quaternary geology of Chatham Island has been investigated using several different techniques, including: tephrochronology, mineralogy, palynology and stratigraphy; in an attempt to draw together a Quaternary history for the Island. The Quaternary record of Chatham Island comprises mainly deposits from terrestrial environments, predominantly thick blanket peats and aeolian sand, all of which range from latest Castlecliffian to Haweran/Recent in age. Quaternary deposits that demonstratably predate this age range (i.e. > Oxygen Isotope Stage 12) have not been recognised anywhere on the Island. Their absence is, at this stage, attributed to a major marine transgression across much of the northern and central portions of the Island during Oxygen Isotope Stage 11. Two rhyolitic tephra produced during two of the largest eruptions from the Taupo Volcanic Zone are present on Chatham Island. The 27.1 ka Kawakawa Tephra is well preserved across most of the Island, occurring within most pre-Holocene sequences. The 345 ka Rangitawa Tephra, not previously recognised on Chatham Island, is found in a few scattered coastal locations where older, late Castlecliffian sediments are preserved. In the absence of any other forms of radiometric age control these two tephras have provided the principal means for time control within and between stratigraphic sequences on the Island. Palynology has been used predominantly to determine climatic conditions at the time of sediment accumulation. Palynological investigations of seven sections of peat deposits have also demonstrated that cyclic changes in vegetation patterns have occurred throughout the Quaternary on Chatham Island. However these changes have not been as significant as those that occurred on mainland New Zealand over the Quaternary. It is concluded that this indicates climatic deterioration during glacials may not have been as pronounced on Chatham Island as on the mainland. Marine terraces created during former high sea level stands are preserved in several areas on Chatham Island. Quaternary terrace surfaces ranging in age from Last Interglacial (OIS 5e) to OIS 11 occur at heights of 3-5 m, 9 – 10 m, 16 m, 20 m and 30 - 40 m above sea level. An exhumed surface of Late Pliocene age occurs at 7 – 14 m a.s.l.. Terrace ages have been determined using cover-bed stratigraphy, and in particular the presence or absence of tephra marker beds. Height-age relationships of marine terraces have been used to develop preliminary rates of tectonic uplift on Chatham Island. The resulting values range between 0.01 – 0.13 mm/yr and are very low compared with more tectonically active areas of mainland New Zealand. However, there is considerable variation in these rates across Chatham Island, indicating that the tectonic history of the Island over the Quaternary may be complex. This thesis has also demonstrated that considerably more work is required to fully understand the Quaternary history of Chatham Island. In particular, better numerical age control on key deposits; more detailed, high-resolution pollen records from key locations; and obtaining stratigraphic records from a greater range of locations. This is particularly so for the southern uplands where older records are virtually inaccessible due to a thick blanketing of post-glacial peat deposits.

Andesitic volcanoes are notorious for their rapid and unpredictable changes in eruptive style between and during volcanic events, a feature normally attributed to shallow crustal and intra-edifice magmatic processes. Using the example of eruptions during the last 1000 yrs at Mt. Taranaki (the Maero Eruptive Period), deposit sequences were studied to (1) understand lava dome formation and destruction, (2) interpret the causes of rapid shifts from extrusive to explosive eruption styles, and (3) to build a model of crustal magmatic processes that impact on eruption style. A new detailed reconstruction of this period identifies at least 10 eruptive episodes characterised by extrusive, lava dome- and lava flow-producing events and one sub- Plinian eruption. To achieve this, a new evaluation procedure was developed to purge glass datasets of contaminated mineral-glass analyses by using compositional diagrams of mineral incompatible-compatible elements. Along with careful examination of particle textures, this procedure can be broadly applied to build a higher degree of resolution in any tephrostratigraphic record. Geochemical contrasts show that the products of the latest Mt. Taranaki eruption, the remnant summit dome (Pyramid Dome) was not formed during the Tahurangi eruptive episode but extruded post-AD1755. Its inferred original maximum volume of 4.9×106 m3 (DRE) was formed by simultaneous endogenous and exogenous dome growth within days. Magma ascent and extrusion rates are estimated at =0.012 ms-1 and =6 m3s-1, respectively, based on hornblende textures. Some of the Maero-Period dome effusions were preceded by a vent-clearing phase producing layers of scattered lithic lapilli around the edifice [Newall Ash (a), Mangahume Lapilli, Pyramid Lapilli]. The type of dome failure controlled successive eruptive phases in most instances. The destruction of a pressurised dome either caused instantaneous but short-lived magmatic fragmentation (Newall and Puniho episodes), or triggered a directed blast-explosion (Newall episode), or initiated sustained magmatic fragmentation (Burrell Episode). The transition from dome effusion to a sustained, sub- Plinian eruption during the Burrell Lapilli (AD1655) episode was caused by unroofing a conduit of stalled magma, vertically segregated into three layers with different degrees of vesiculation and crystallisation. The resultant ejecta range from brown, grey and black coloured vesicular clasts to dense grey lithics. Bulk compositional variation of erupted clasts can be modelled by fractionation of hornblende, plagioclase, clinopyroxene, and Fe-Ti oxides. Pre-eruption magma ascent for the Maero Period events is assumed to begin at depths of c.9.5 km.

This thesis presents a detailed late Tertiary and early Quaternary pollen record from two c. 40 m long sedimentary cores (the Patiki cores) from west Auckland. The cores consist of slightly to highly carbonaceous clays, with a thick sand incursion at mid-depth. The sediments below the sand incursion are aged through palynostratigraphy as mid-late Pliocene (Hautawan). The sediments above the sand incursion have numerous interbedded tephras, and are aged through a combination of Isothermal Plateau Fission Track dating, palaeomagnetism and orbital tuning to the marine oxygen isotope record as 1.0 – 1.4 Ma (MIS 28 - 45, Marahauan substage). The Tertiary pollen record portrays regional vegetation assemblages of extinct Nothofagus brassii-type species and modern-day podocarps, with local modern-day oligotrophic mire assemblages. A cool climatic phase is indicated by a period of dominance of an extinct member of the Proteaceae. However, the duration of this interval cannot be determined due to a lack of numerical age control for the record. The Quaternary pollen record consists of mostly extant pollen types. It shows multiple compositional shifts from Nothofagus-dominated to conifer-dominated regional vegetation, with local oligotrophic mire vegetation except for a fully aquatic phase at mid-depth (MIS 35). The primary axis score curve of a detrended correspondence analysis (DCA) of the pollen record was correlated to the marine isotope record, and shows that the Nothofagus-dominated intervals correspond to cool climate stages, while the conifer-dominated intervals correspond to warm stages. The strongest cool stage maximum is indicated at 12 - 13 m depth (MIS 34), where the vegetation consists of Fuscospora, Prumnopitys taxifolia and heath shrubs. The strongest warm stage maximum is indicated at c. 9 m depth (MIS 31) where the vegetation consists of Dacrydium forest. Astronomically forced climate change is an important driving force behind vegetation composition changes portrayed in the Quaternary pollen record. The majority of warm stage maxima inferred in the pollen record (conifer-dominated intervals) coincide with periods of maximum obliquity, and vice versa for inferred cool stage maxima (Nothofagus-dominated intervals). The modulating effect of eccentricity on precession is influential on the pollen record during MIS 31 and 34. The relationship between selected climate indicator taxa and calculated insolation values indicates that reduced seasonality in Auckland during warm climate stages favours Agathis, Dacrydium, Phyllocladus and Halocarpus, while increased seasonality during cool climate stages favours Nothofagus ‘fusca'-type, Nothofagus menziesii, and Prumnopitys taxifolia. In both situations the trees are probably responding to a combination of changes in mean global temperatures and seasonality, and reacting according to their own adaptive responses to astronomically driven climate change. The Quaternary pollen record contains plant mixtures that do not occur in New Zealand today, for example Agathis australis with Nothofagus menziesii, and Halocarpus bidwillii / biformis. The climate was probably cooler than it is in Auckland today, but never as cold as the last glacial maximum in Auckland when grasslands were present. Under more equable climatic conditions, with less extreme glacial and interglacial cycles, populations of comparably 'warm' and 'cool' climate taxa were probably able to shift throughout the region and mixed to a greater extent than is currently observed. The overall vegetation response to climate change (particularly above MIS 36) is analogous to that recorded in northern New Zealand in the late Pleistocene, and supports a negligible change in climatic preference of the main canopy species since the early Quaternary. The phytosociological idiosynchracies in the pollen record are not inconsistent with the known tolerance limits of the taxa involved, or with the individualistic nature of vegetation composition.

Antimony (Sb) is an element of increasing concern as an environmental contaminant. Geothermal systems are a potential source of Sb in the fresh waters of New Zealand’s North Island, but little is known about the element’s behaviour within geothermal fluids, and even less about the eventual fate of geothermally produced Sb. The purpose of this thesis was to determine the factors controlling geothermal Sb behaviour in a range of environments, in order to begin to develop an understanding of the eventual fate of Sb produced from geothermal systems. Factors controlling Sb precipitation at two New Zealand geothermal power stations, were determined using field measurements and geochemical model predictions. Approximately 75 % of the incoming Sb, which ranged from 960 – 1650 μg/kg in the incoming fluids was removed from solution within the Ngawha and Rotokawa power stations. It was found that changes in pH and temperature were the most important factors controlling stibnite (Sb2S3) precipitation. Thermodynamic databases could be used to model this precipitation process, once updated with recent published Sb2S3 solubility data. The mobility of Sb from Sb2S3 precipitates in geothermal features at Wai-O-Tapu and Waimangu, two New Zealand geothermal fields, were investigated. At Wai-O-Tapu, daytime variations in aqueous Sb concentrations from the discharge of Champagne Pool may be due to to changing sulfide-sulfate equilibria coupled with photosynthetic bacterial processes. While daytime concentrations of Sb approached 200 μg/kg, most of the Sb remobilised by such mechanisms appears to be removed by adsorption onto suspended particulate material (SPM) or reprecipitation (as Sb2S3) in an anoxic, low pH lake feature downstream. Concentrations of Sb in the discharge from Alum Lake were below the analytical detection limit (<0.2 μg/kg). At Waimangu, these daytime fluctuations were not observed in the discharge of Frying Pan Lake, and concentrations of Sb were ~13 μg/kg. In the absence of any downstream acidic waters, no precipitation was observed and only minor adsorption onto SPM was observed. Most of the Sb produced from Frying Pan Lake is therefore transported into Lake Rotomahana, the system’s receiving environment. Natural Sb removal processes in receiving (non-geothermal) environments were also assessed. In the Waikato River, Sb concentrations were low (~1 μg/kg), compared to those observed in geothermal environments studied. The most important process was adsorption to SPM, which is enhanced at low (< 5) pH conditions, or in the anoxic base of stratified lakes. In Lake Ohakuri, which was stratified during the summer of 2007, there was also the potential for the removal of Sb as Sb2S3 in the presence of sulfide species that form in the anoxic layer. There was evidence that the adsorption of Sb changes with changing Fe concentrations in suspended particulate material, and therefore Sb adsorption was higher in winter than in summer. The behaviour of Sb was conservative in the Port Waikato estuary at the mouth of the river. Throughout the research, Sb was compared to arsenic (As), a metalloid previously thought to exhibit behaviour similar to Sb in aquatic environments. It was found that while any removal processes shown to affect Sb will also affect As, the inverse did not necessarily apply. Arsenic will adsorb more readily to SPM than Sb and, while there was evidence for bioaccumulation of As by geothermal algae and freshwater macrophytes, there was no such evidence for Sb. Therefore, if geothermally-derived Sb and As did ever significantly contaminate a downstream environment, it should not be assumed that the processes mitigating As contamination will necessarily also apply to Sb.

The long-term behaviour of andesitic stratovolcanoes is characterised by a repetition of edifice growth and collapse phases. This cyclic pattern may represent a natural frequency at varying timescales in the growth dynamics of stratovolcanoes, but is often difficult to identify because of long cycle-timescales, coupled with incomplete stratigraphic records. The volcaniclastic ring-plain succession surrounding the 2 518 m Mt. Taranaki, New Zealand, comprises a wide variety of distinctive volcanic mass-flow lithofacies with sedimentary and lithology characteristics that can be related to recurring volcanic cycles over >190 ka. Debrisflow and monolithologic hyperconcentrated-flow deposits record edifice growth phases while polylithologic debris-avalanche and associated cohesive debris-flow units were emplaced by collapse. Major edifice failures at Mt. Taranaki occurred on-average every 10 ka, with five events recognised over the last 30 ka, a time interval for which stratigraphic records are more complete. The unstable nature of Mt. Taranaki mainly results from its weak internal composite structure including abundant saturated pyroclastic deposits and breccia layers, along with its growth on a weakly indurated and tectonically fractured basement of Tertiary mudstones and sandstones. As the edifice repeatedly grew beyond a critical stable height or profile, large-scale collapses were triggered by intrusions preceding magmatic activity, major eruptions, or significant regional tectonic fault movements. Clasts within debris-avalanche deposits were used as a series of windows into the composition of previous successive proto-Mt Taranaki edifices in order to examine magmatic controls on their failure. The diversity of lithologies and their geochemical characteristics are similar throughout the history of the volcano, with the oldest sample suites displaying a slightly broader range of compositions including more primitive rock types. The evolution to a narrower range and higher-silica compositions was accompanied by an increase in K2O. This shows that later melts progressively interacted with underplated amphibolitic material at the base of the crust. These gradual changes imply a long-term stability of the magmatic system. The preservation of similar internal conditions during the volcano’s evolution, hence suggests that external processes were the main driving force behind its cyclic growth and collapse behaviour and resulting sedimentation pattern.

Realistic probabilistic hazard forecasts for re-awakening volcanoes rely on making an accurate estimation of their past eruption frequency and magnitude for a period long enough to view systematic changes or evolution. Adding an in-depth knowledge of the local underlying magmatic or tectonic driving processes allows development of even more robust eruption forecasting models. Holocene tephra records preserved within lacustrine sediments and soils on and surrounding the andesitic stratovolcano of Mt. Taranaki (Egmont Volcano), New Zealand, were used to 1) compile an eruption catalogue that minimises bias to carry out frequency analysis, and 2) identify magmatic processes responsible for variations in activity of this intermittently awakening volcano. A new, highly detailed eruption history for Mt. Taranaki was compiled from sediment sequences containing Holocene tephra layers preserved beneath Lakes Umutekai and Rotokare, NE and SE of the volcano’s summit, respectively, with age control provided by radiocarbon dating. To combine the two partly concurrent tephra records both geochemistry (on titanomagnetite) and statistical measures of event concurrence were applied. Similarly, correlation was made to proximal pyroclastic sequences in all sectors around the 2518 m-high edifice. This record was used to examine geochemical variations (through titanomagnetite and bulk chemistry) at Mt. Taranaki in unprecedented sampling detail. To develop an unbiased sampling of eruption event frequency, a technique was developed to distinguish explosive, pumice-forming eruptions from dome-forming events recorded in medial ash as fine-grade ash layers. Recognising that exsolution lamellae in titanomagnetite result from oxidation processes within lava domes or plugs, their presence within ash deposits was used to distinguish falls elutriated from blockand- ash flows. These deposits are focused in particular catchments and are hence difficult to sample comprehensively. Excluding these events from temporal eruption records, the remaining, widespread pumice layers of sub-plinian eruptions at a single site of Lake Umutekai presented the lowest-bias sampling of the overall event frequency. The annual eruption frequency of Mt. Taranaki was found to be strongly cyclic with a 1500-2000 year periodicity. Titanomagnetite, glass and whole-rock chemistry of eruptives from Mt. Taranaki’s Holocene history all display distinctive compositional cycles that correspond precisely with the event frequency curve for this volcano. Furthermore, the largest known eruptions from the volcano involve the most strongly evolved magmas of their cycle and occur during the eruptive-frequency minimum, preceding the longest repose intervals known. Petrological evidence reveals a two-stage system of magma differentiation and assembly operating at Mt. Taranaki. Each of the identified 1500-2000 year cycles represent isolated magma batches that evolved at depth at the base of the crust before periodically feeding a mid-upper crustal magma storage system.

Acid mine drainage (AMD) typically involves waters with low pH (pH 2-4) and high concentrations of Fe, SO4 and potentially toxic trace metals. Adsorption onto iron oxyhydroxides is the dominant mechanism controlling the transport and toxicity of trace metals in water bodies impacted by AMD. The purpose of this study was to apply the Diffuse Layer Model (DLM) to describe the adsorption of trace metals by iron oxyhydroxides from these systems, using synthetic iron oxyhydroxide minerals, ferrihydrite, pure acicular goethite, SO4-rich goethite prepared from FeSO4 oxidation and a synthetic schwertmannite. The ferrihydrite adsorption of the trace metals Cu, Zn, Cd and Co from single sorbate systems was accurately described using the DLM with two surface site types (type-1 and type-2) having site densities of 0.005 and 0.2 mol (mol Fe)-1 respectively. The ferrihydrite adsorption of SO4 from single sorbate systems was accurately described using the DLM with adsorption on the type-2 sites. However, the enhanced adsorption of Cu, Zn, Cd and Co in the presence of SO4 was not predicted using adsorption constants derived from single sorbate systems. By including a neutral ternary complex with stoichiometry Fe(2)OHMeSO4 (where Fe(2)OH is a type-2 surface site and Me is the trace metal) the effect of SO4 on metal adsorption was accurately described for the range of Me, Fe and SO4 concentrations studied. The adsorption of Cu and Zn onto schwertmannite at total metal to iron ratios (MeT:Fe) up to 8 x 10-3 was almost identical to that predicted for ferrihydrite in the presence of 0.01 mol kg-1 SO4. To model the ferrihydrite adsorption of Pb from single sorbate systems a third higher affinity site (type-0) with a site density of 0.00035 mol (mol Fe)-1 was required. The effect of SO4 on Pb adsorption could only be modelled by including a neutral ternary complex on both the type 1 and type 2 sites in the case of Pb. Metal adsorption onto a pure acicular goethite could be accurately described by the DLM with two surface site types. The type 2 site density that provided the best fit to the goethite adsorption data was 0.027 mol (mol Fe)-1 corresponding to 2.3 nm-2. The type-1 site density that provided the best fit to goethite adsorption of Cu, Pb and Cd was 0.00028 mol (mol Fe)-1 corresponding to 0.024 nm-2. For Zn adsorption on goethite the type-1 site density was significantly larger at 0.0015 mol (mol Fe)-1 corresponding to 0.13 nm-2. In all cases studied the presence of SO4 caused an increase in the extent of metal adsorption by goethite. This increased adsorption of metals in the presence of SO4 was accurately predicted by including ternary complex formation at both the high and low affinity adsorption sites. For both ferrihydrite and goethite the values of adsorption constants for ternary complex formation (logKxMeTC) were related to the adsorption constant for metal adsorption in the absence of SO4 (logKxMeINT). This was evident from a plot of logKxMeTC as a function of logKxMeINT for all metals, which showed a linear relationship with slope of 0.69 and intercept of 8.03. This relationship suggests that the enhancement of metal adsorption on both oxyhydroxides due to SO4 occurs by the same process. When comparing Cu, Zn and Cd adsorption onto ferrihydrite and acicular goethite the effect of the larger goethite adsorption constants are approximately compensated for by the lower goethite site densities. Therefore the Cu, Cd and Zn adsorption isotherms on ferrihydrite and acicular goethite are fairly similar at low adsorption densities. In the case of Pb, the site densities and adsorption constants are both larger on ferrihydrite and there is a large difference between the ferrihydrite and acicular goethite adsorption isotherms. Sulfate-rich goethite had considerably higher site densities, per mol of oxide, than the pure acicular goethite. Adsorption onto the sulfate-rich goethite could be modelled reasonably accurately using the parameters developed to model adsorption onto the pure acicular goethite but with a higher surface area and a higher ratio of type-1 to type 2 sites. In general, therefore, the parameters developed for pure goethite are apparently similar to those for the sulfate-rich goethite, but are not directly transferable. The difficulty in measuring the surface area of the highly aggregated sulfate-rich goethite makes comparisons between the two goethites more difficult. The adsorption of Cu, Zn and Cd onto the SO4-rich goethite exceeds that of ferrihydrite because the higher adsorption constants of goethite are combined with the considerably higher site densities of the SO4-rich goethite compared to the acicular goethite. In contrast the higher site densities of the SO4-rich goethite does not completely compensate for the low logKINT values of Pb adsorption on goethite. Therefore SO4-rich goethite adsorption of Pb is lower than that of ferrihydrite. When applied to literature data from AMD oxides the parameters derived in this thesis have significantly improved the ability of the DLM to predict trace metal adsorption in AMD systems, compared to using ferrihydrite as a proxy for all iron oxyhydroxides and adsorption data derived only from single sorbate systems.