[Truncated abstract] Most of Australia, and large areas of many other continents, is drained by intermittent rivers and streams, however comparatively few biogeochemical studies have been completed for these systems. Intermittent, dryland streams are highly dynamic environments subject to unpredictable and sporadic flow. Natural disturbance from lengthy drought periods and sudden floods are typical for these systems. Without adequate baselines for natural disturbances, it is difficult to quantify other effects from anthropogenic disturbance such as dewatering, land clearing, and urbanisation, or climate change. This thesis presents work from a four-year study examining the biogeochemistry of nitrogen (N), phosphorus (P) and carbon (C) in soils and sediments of two intermittent streams (Barnett Creek and Pirraburdoo Creek) in the Pilbara region of north-west Australia. The Pilbara is an area of ancient geology and highly weathered environments that is undergoing rapid development yet is poorly understood from an ecological perspective. The principal objectives of this thesis were to determine: i) how flooding affects the spatiotemporal patterns of nutrients in intermittent stream landscapes; ii) the role of flooding in N and C mineralisation and microbial dynamics; and iii) the connections between benthic algae, microbes and nutrient availability in channel sediments. To address these objectives, three field studies and two incubation experiments were conducted. Field studies at Barnett Creek indicated that flooding reduced the spatial heterogeneity of available soil nutrients and microbes in the stream landscape, and that topography (relative elevation) in the stream landscape was of less importance in influencing nutrient and microbial patterns than flooding or landscape position. ... Field studies at Pirraburdoo Creek indicated that microbial biomass and activity increased in benthic algal mats during mat senescent stages, and decreased after flooding when mat biomass peaked. Benthic algae grew rapidly in gravel run environments after flooding, while declining in pools, and demonstrated moderate N limitation and strong P limitation. Pools had two to eight times greater NO3-N, three to five times more total N, and two to three times more labile P, OC and total C than either pools after flooding, or runs before or after flooding. Hence, the pools at Pirraburdoo Creek represented a local, interflood store of nutrients in otherwise nutrient-poor landscape, when connectivity to upstream reaches or upland environments was weak or non-existent. This thesis provides the first detailed analysis of soil and sediment biogeochemical responses to flooding for intermittent streams in the Pilbara region and for semi-arid Australia. Further pressing questions raised by this work include: What is the key pulse size and frequency for maintaining Pilbara riparian communities as well as soil microbial function? How do the spatio-temporal nutrient and microbial patterns observed persist over (i) multi-decadal scales, (ii) mega-spatial (larger landscape to regional) scales, (iii) different flood frequency-magnitude regimes, and (iv) different stream sizes? Stream biogeochemistry is a burgeoning field, and it is therefore reasonable to expect such existing gaps in knowledge may be addressed in the near future.

[Truncated abstract] Detailed sedimentological, petrographical, geochemical and palynological studies have provided insight into the source rocks and the processes that operated during formation of the Tertiary Yandi channel iron deposit (CID) of the eastern Pilbara, Western Australia. Yandi is the largest and most valuable CID in the world, accounting for more than 2.5% of global iron production in 2003, and is the type-example of CID. The Yandi CID occupies the palaeo-Marillana Creek in the central Hamersley Ranges. It is near-coincident-with the modern Marillana Creek which incised Proterozoic bedrock of the Weeli Wolli Formation (Hamersley Group) and associated dolerite intrusions. Three lithostratigraphic units fill the palaeo-Marillana Creek and comprise the Marillana Formation. The units in stratigraphic order are the: (1) Munjina Member; (2) Barimunya Member, which hosts the majority of the iron resource; and (3) Iowa Eastern Member. Fossil pollen and spores in organic-rich claystones in the Munjina Member indicate that deposition of the Marillana Formation most likely commenced in the Early Oligocene in response to erratic seasonal flows with high energy flood events and intervening quiescent suspension settling of clays. The Marillana Formation consists of twelve facies. These conglomerate and clay facies form three facies associations. The basal facies association is composed of polymictic conglomerate, clay and interbedded CID that represents a lag deposit along the base of the palaeochannel. This facies association characterises the Munjina Member. The second facies association consists of iron-rich conglomerate sheets, bars and subordinate scour-fills and characterises the Barimunya Member. Channel iron deposits of the overlying Iowa Eastern member consist of reworked Barimunya Member iron conglomerates. The upper facies association is polymictic conglomerate with clay that characterises the remainder of the Iowa Eastern Member. Polymictic iron conglomerate in the Munjina and Barimunya Members contains Weeli Wolli Formation and dolerite clasts indicating local derivation. Rare earth element profiles of the other iron conglomerate facies indicate derivation of the Barimunya and Iowa Eastern CID from a different source. These iron conglomerates are characterised by relatively flat LREE profiles. The LREE exhibit an enriched profile approaching the MREE [(average La/Nd)N = 0.7], and the HREE profile shows minor enrichment approaching ytterbium [(average Dy/Yb)N = 0.9]. Comparison of iron conglomerate REE profiles to those of the bedrock indicates that these conglomerates were most probably derived from the Joffre Formation BIF of the Hamersley Group

The Mt. Tom Price Mine, located in the Pilbara region of Western Australia, has been the site of major iron ore mining since the 1960s by Rio Tinto Iron Ore/Pilbara Iron. The thesis project area covers approximately 121 km², covering the Mt. Tom Price Mining area and the surrounding catchment boundary. The climate in the Pilbara region is arid, with rainfall driven by seasonal cyclonic events, producing 300 mm/year net rainfall on average. The geology of the Mt. Tom Price area consists of a series of banded iron formations (BIF) and shales that are generally low in hydraulic conductivity values. Iron ore in the region is produced through the process of supergene enrichment whereby gangue minerals are dissolved and replaced with haematite and goethite. Mining is focused in a series of open cast pits including, North Deposit, West Pits, Centre Pits, Southern Ridge, South East Prongs, Section Six, Section Seven, and the proposed Marra Mamba Pits. Due to the impermeable nature and complex geology of the BIF sequence, groundwater flow is dominated by bedrock aquifer flow, with compartmentalization occurring in several areas of the mine. Highly faulted and folded units can also have increased hydraulic conductivity values. Pit floor lowering began to encounter the regional water table in early 1994. A series of dewatering bores and depressurization measurements have been utilized to ensure dry mining practice. This data was used to help understand regional groundwater flow and create the Mt. Tom Price Groundwater Model (MTPGM). A 3D geological model of the project area was created to aid visualisation of semi-regional hydrogeology. From this model, accurate template files were created so that geological detail loss is kept to a minimal when entering hydrogeological parameters into the MTPGM. The MTPGM was setup using PMWIN Pro, a graphical user interface for use with MODFLOW. Stresses such as recharge and pumping were entered via software packages within MODFLOW. The model was run to simulate measured 1994-2007 responses to dewatering and high rainfall events. A Parameter Estimation (PEST) software package and trial and error calibration was used to lower stress response variances that were observed in the model output files. This was achieved by the adjustment of hydrogeological parameters such as hydraulic conductivity and specific yield values. A prediction simulation of final pit lake recovery was created Using the calibrated MTPGM. Recovery curves predicted that full recovery of the water table of the pit voids varied from 96 to 120 years, recovering to levels close to the initial heads measured in 1994 before large-scale pumping commenced. The hydrochemistry of the groundwater in the mining area is highly influenced by geological hosts, with clearly defined hydrochemical signatures approximated for each screened geological unit. Due to the sulphur rich, acid- forming Mt. McRae Shale, regular monitoring of pit and groundwater is essential. Final pit lake water quality was estimated using final pit levels and recovery rates approximated from the MTPGM, combined with historical data and previous groundwater quality reports. Pit lake water quality is dominantly driven by evaporation concentration, caused by high evaporation rates and low throughflow. Pit waters are expected to be brine waters (greater than 100,000 mg/L TDS), with high levels of acidity values occurring in the South East Prongs and Section Six pits due to the exposure of the acid forming Mt. McRae Shale above the pit lakes at these localities. Future studies should focus on more detailed modelling of the compartmentalised aquifer systems. This would produce much more accurate final pit lake levels. Further study of the Mt. McRae Shale formation and its implications on acidity should also be undertaken. Seasonal fluctuations in lake levels will affect acidity due to the continual re-exposure and oxidation of the Mt. McRae Shale. This could be studied to help understand short term pit lake quality conditions and help to predict long term acidity conditions in the pit lakes.

Invasive plants pose serious threats to economic, social and environmental interests throughout the world. Developing strategies for their management requires a range of information that is often impractical to collect from ground based surveys. In other cases, such as retrospective analyses of historical invasion rates and patterns, data is rarely, if ever, available from such surveys. Instead, historical archives of remotely sensed imagery provides one of the only existing records, and are used in this research to determine invasion rates and reconstruct invasion patterns of a ca 70 year old exotic mesquite population (Leguminoseae: Prosopis spp.) in the Pilbara Region of Western Australia, thereby helping to identify ways to reduce spread and infill. A model was then developed using this, and other, information to predict which parts of the Pilbara are most a risk. This information can assist in identifying areas requiring the most vigilant intervention and pre-emptive measures. Precise information of the location and areal extent of an invasive species is also crucial for land managers and policy makers for crafting management strategies aimed at control, confinement or eradication of some or all of the population. Therefore, the third component of this research was to develop and test high spectral and spatial resolution airborne imagery as a potential monitoring tool for tracking changes at various intervals and quantifying the effectiveness of management strategies adopted. To this end, high spatial resolution digital multispectral imagery (4 channels, 1 m spatial resolution) and hyperspectral imagery (126 channels, 3 m spatial resolution) was acquired and compared for its potential for distinguishing mesquite from coexisting species and land covers. / These three modules of research are summarised hereafter. To examine the rates and patterns of mesquite invasion through space and time, canopies were extracted from a temporal series of panchromatic aerial photography over an area of 450 ha using unsupervised classification. Non-mesquite trees and shrubs were not discernible from mesquite using this imagery (or technique) and so were masked out using an image acquired prior to invasion. The accuracy of the mesquite extractions were corroborated in the field and found to be high (R2 = 0.98, P<0.001); however, accuracy varied between classes (R2 = 0.55 to 0.95). Additional sampling may be required in some of the wider class intervals, particularly the moderate density class (30 to 90%) as sampling frequency was poor within the range of 60 to 90%. This is a direct result of there being relatively few quadrats available to be randomly selected in this class. That is, quadrats with between 60-90% cover were only evident in 4% of the test area. A more robust approach would, therefore, be to split this class into two (e.g. 30-60% and 60-90%) and select an additional 15 quadrats in the 60-90% range. The resolution of the imagery (1.4 m) precluded mapping shrubs smaller than 3 m2. Rates and patterns were compared to mesquite invasions in its native range. / It was determined that: (i) the shift from grass to mesquite domination had been rapid, with rates of increase in canopy cover comparable to invasive populations where it is native; (ii) rate of patch recruitment was high in all land types (stony flats, red-loamy soils and the riparian zone), but patch expansion and coalescence primarily occurred over the riparian zone and redloamy soils; (iii) mesquite had been spread by sheep and macropods and the recent switch to cattle is likely to exacerbate spread as it is a far more effective dispersal vector; and (iv) early successional patterns, such as high patch initiation followed by coalescence of existing stands are similar to where mesquite is native, but patch mortality did not occur. A knowledge based model was used to predict which parts of the Pilbara region are most at risk. Several limitations of models often employed in predicting suitability ranges of invasive plants were identified and include: (i) an inability to incorporate the notion that within a suitability range there is likely to be a scale of favourability; (ii) an inability to assign greater importance to evidence that is likely to have more importance in defining the areas suitable for invasion; and (iii) an inability to control the level of conservatism in the final results. These three shortcomings were mitigated through the use of: (i) fuzzy membership functions to derive a range of favourability from poor to best; (ii) pairwise comparison to derive higher weights for layers perceived to be more important and vice versa; and (iii) the use of ordered weighted averaging to directly control the level of conservatism (or risk) inherent in the models produced. / Based on the outcomes of the historical reconstruction of spatial rates and patterns, data sources included land types, land use, and the derivation of a steady state wetness index from spot height data. Model outputs were evaluated using two methods: the area under the curves (AUC) produced from relative operating characteristic (ROC) plots and by the maximum Kappa procedure. Both techniques agreed that the model most representative of the validation data was the one assuming the most risk. To create a Boolean output representing areas suitable/not suitable for invasion, optimal cut-points were derived using the point closest to the top left hand corner of the ROC plot and by the maximum Kappa method. Both methods obtained identical cut-points, but it is argued that the coefficient produced by the maximum Kappa method is more easily interpreted. The highest AUC was found to be 0.87 and, based on the maximum Kappa method, can be described as good to very good agreement with the validation records used. Digital multispectral imagery (DMSI), acquired in the visible and near infrared portions of the spectrum (3 visible bands, 1 near infrared) with a spatial resolution of 1 m and hyperspectral imagery (126 bands, 3 m spatial resolution) was acquired to assess the potential of developing a reliable and repeatable mapping tool to facilitate the monitoring of spread and the effects of control efforts. Woody vegetation was extracted from the images using unsupervised classification and grouped into patches based on contiguity. Various statistics (e.g. maximum, minimum, median, mean, standard deviation, majority and variety) were assigned to these patches to garner more information for species separation. / These statistics were explored for their ability to separate mesquite from coexisting species using Tukey’s Honestly Significantly Different (HSD) test and, to reduce redundancy, followed by linear discriminant analysis. Two approaches were taken to select the patch statistics offering the best discrimination. The first approach selected patch statistics that best discriminated all species (named “overall separation”). This was compared to a second approach, which selected the best patch statistics that separated each species from mesquite on a pairwise basis (named “pairwise separation”). The statistics offering the best discrimination were used as input in an Artificial Neural Network (ANN) to assign class labels. An incremental cover evaluation, whereby producer’s accuracy was computed from mesquite patches grouped into various size-classes, showed that identification of mesquite patches smaller than 36 m2 was relatively low (43-51%) regardless of the method used for choosing between the patch statistics or image type. Accuracy improved for patches >36 m2 (66-94%) with both approaches and image types. However, both approaches used on the hyperspectral imagery were more reliable at capturing patches >36 m2 than the DMSI using either approach. The lowest omission and commission rates were obtained using pairwise separation on the hyperspectral imagery, which was significantly more accurate than DMSI using an overall separation approach (Z=2.78, P<0.05), but no significant differences were found between pairwise separation used on either media. / Consequently, all methods and imagery types, except for DMSI processed using overall separation, are capable of accurately mapping mesquite patches >36 m2. However, hyperspectral imagery processed using pairwise separation appears to be superior, even though not statistically different to hyperspectral imagery processed using overall separation or DMSI processed using pairwise separation at the 95% confidence level. Mapping smaller patches may require the use of very high spatial resolution imagery, such as that achievable from unmanned airborne vehicles, coupled with a hyperspectral instrument. Alternatively, management may continue to rely on visual airborne surveys flown at low altitude and speed, which have proven to be capable at mapping small and isolated mesquite shrubs in the study area used in this research.

This thesis is a history of schooling for Indigenous children in Western Australia between the commencement of the first Aboriginal school in Perth in 1840 and 1978. The thesis represents the view that, for most of this period, and regardless of policy, education for Indigenous children was directed towards changing their beliefs and behaviours from being distinctly Aboriginal to recognizably European. Four major policies for Aborigines provide the framework for the thesis, these being amalgamation (1840-1852), protection (1886-1951), assimilation (1951-1972) and self-determination (1973- ). The amalgamation of the Indigenous popuIation with the small colonial society in Western Australia was a short-lived policy adopted by the British Colonial Office. Protection, a policy formalised by Western Australian legislation in 1886, 1905 and 1936, dominated Aboriginal affairs for the first half of the 2ofh century. Under this policy the Indigenous population was regarded as two distinct groups - a diminishing traditional population to be segregated and protected and an increasing part-Aboriginal population that was to be trained and made 'useful'. In 1951 Western Australia accepted a policy of assimilation, coordinated by the Commonwealth government, which anticipated that all people of Aboriginal descent would eventually be assimilated into the mainstream Australian society. This policy was replaced in 1973 by one of Aboriginal community self-determination, an initiative of the Commonwealth government and adopted throughout Australia. The attempts at directed cultural change were evident in the 'Native' schools that opened in Perth, Fremantle and Guildford in the 1840s where it was assumed that the separation of children from their families and a Christian education would achieve the transition from a 'savage to civilized' state. For another century the education of Indigenous children on missions and in government settlements was founded upon similar assumptions. The thesis acknowledges that the principal change agents, such as the Chief Protectors of Aborigines, mission administrators and the teachers in direct contact with the children, seriously underestimated both the enduring nature of Indigenous culture and the prejudice in Australian society. Between 1912 and 1941 a few government schools in the southern districts of Western Australia refused to admit Aboriginal children. The exclusion of these children is examined against a background of impoverished living conditions, restrictive legislation and mounting public pressure on the State and Commonwealth governments for a change in policy. The change did not begin to occur until 1951 when the Commonwealth and States agreed to a policy of assimilation. In Western Australia this policy extended education to all Aboriginal children. The thesis explores the provision of government teachers to Aboriginal schools in remote areas of Western Australia between 1951 and 1978. The final chapter examines Indigenous perceptions of independent community schools within the fust five years of the policy of self-determination and contrasts the objectives and management of two schools, Strelley in the Pilbara and Oombulguni in the Kimberley.

[Truncated abstract. Formulae and special characters can only be approximated here. Please see the pdf version of this abstract for an accurate representation.] The 3.24 Ga Panorama VMS District, located in the Pilbara Craton of Western Australia, is exposed as a cross-section through subvolcanic granite intrusions and a coeval submarine volcanic sequence that hosts Zn-Cu mineralization. The near-complete exposure across the district, the very low metamorphic grade, and the remarkable preservation of primary igneous and volcanic textures provides an unparalleled opportunity to examine the P-T-X-source evolution of a VMS ore-forming system and to assess the role of the subvolcanic intrusions as heat sources and/or metal contributors to the overlying VMS hydrothermal system. Detailed mapping of the Panorama VMS District has revealed seven major vein types related to the VMS hydrothermal system or to the subvolcanic intrusions. (1) Quartz-chalcopyrite veins, hosted in granophyric granite immediately beneath the granite-volcanic contact, formed prior to main stage VMS hydrothermal convection, and were precipitated from mixed H2OCO 2-NaCl-KCl fluids with variable salinities (2.5 to 8.5 wt% NaCl equiv). (2) Quartz-sericite veins, ubiquitous across the top 50m of the volcanic sequence, were formed from an Archean seawater with a salinity of 9.7 to 11.2 wt% NaCl equiv at temperatures of 90° to 135°C. These veins formed synchronous with the regional feldspar-sericite-quartz-ankerite alteration during seawater recharge into the main stage VMS hydrothermal convection cells. (3) Quartz-pyrite veins hosted in granophyric granite, and (4) quartz-carbonate-pyrite veins hosted in andesitebasalt, also formed from relatively unevolved Archean seawater (5.5 to 10.1 wt% NaCl equiv; 150° to 225°C), but during the collapse of the VMS hydrothermal system when cool, unmodified seawater invaded the top of the subvolcanic intrusions. (5) Quartz-topaz-muscovite greisen, (6) quartz-chlorite-chalcopyrite vein greisen, and (7) hydrothermal Cu-Zn-Sn veins are hosted in the subvolcanic intrusions. Primary H2O-NaCl-CaCl2 fluid inclusions in the vein greisens were complex high temperature hypersaline inclusions (up to 590°C and up to 56 wt% NaCl equiv). The H2O-CO2-NaCl fluid inclusions in the Cu-Zn-Sn veins have variable salinities, ranging from 4.9 to 14.1 wt% NaCl equiv, and homogenization temperatures ranging from 160° to 325°C. The hydrothermal quartz veins and magmatic metasomatic phases in the subvolcanic intrusions were formed from a magmatic-hydrothermal fluid that had evolved through wallrock reactions, cooling, and finally mixing with seawater-derived VMS hydrothermal fluids.

La transition Archéen – Protérozoïque (~2,45 Ga) est marquée par des bouleversements environnementaux majeurs dans l’histoire de la Terre (oxygénation de l’atmosphère et glaciations globales). Les séquences sédimentaires qui enregistrent ces événements ont été très étudiées en Amérique du Nord (séquence Huronienne) et en Afrique du Sud (Transvaal). Une séquence analogue sur le craton de Pilbara en Australie Occidentale (groupe de Turee Creek, TCG) contient 3 niveaux de diamictites glaciaires. 3 forages continentaux (Turee Creek Drilling Project, TCDP) ont été réalisés pour étudier la séquence. La géochronologie U-Pb de monazite et zircon dans des échantillons de forage et de surface a daté la première glaciation à 2,45 Ga et la seconde à ~2,34 Ga. Des analyses Re-Os de pyrites de la seconde diamictite ont donné une isochrone à 2,31 Ga. Ces résultats ont permis de proposer un scenario de corrélation des glaciations paléoprotérozoïques enregistrées sur différents continents. Une ‘Snowball Earth’ aurait eu lieu à ~2,45 Ga sur au moins 5 cratons (Pilbara, Kaapvaal, Supérieur, Wyoming, Karélia). Une seconde glaciation aurait pu avoir lieu à ~2,31 Ga sur 4 cratons. L’ensemble des zircons détritiques du TCG ont une distribution d’âge avec des pics à 2,45, 2,54, 2,68, 2,82, 2,95 et 3,2 Ga. Un cristal de zircon Hadéen a été découvert et indique la présence d’une probable croûte différenciée dans le craton de Pilbara à 4,0 Ga. 70% des zircons ont des compositions isotopiques en Hf juvéniles, suggérant que le TCG a incorporé du matériel volcanique provenant de larges provinces ignées continentales à travers l’érosion des groupes sous jacents de Hamersley et Fortescue / The Archean – Proterozoic transition at 2.45 Ga is marked by major environmental changes in Earth’s history (atmosphere oxygenation and global glaciations). The origin and the relationships between these events are debated. Sedimentary sequences that record these events have been widely studied in North America (Huronian sequence) and South Africa (Transvaal). An analog sequence in the Pilbara craton in Western Australia (Turee Creek Group, TCG) contains 3 glacial horizons. 3 continental drill cores (Turee Creek Drilling Project, TCDP) were performed in order to investigate the sequence. U-Pb geochronology of monazite and zircon from drill core and surface samples allows to date the first paleoproterozoic glaciation at 2.45 Ga and a second glacial event at ~2.34 Ga. Re-Os analyses of pyrites from the second diamictite yielded an isochron at 2.31 Ga. These results enable to propose a correlation scenario of the paleoproterozoic glacial events recorded on different continents. A ‘Snowball Earth’ would have occured at 2.45 Ga at least on 5 cratons. A second glaciation could have occured at ~2.31 Ga on 4 cratons. Detrital zircons age spectrum highlights age peaks at 2.45, 2.54, 2.68, 2.82, 2.95 and 3.2 Ga. A crystal of Hadean zircon was discovered and indicate the existence of a probable differentiated crust within the Pilbara craton at 4.0 Ga. 70% of the analyzed zircons have juvenile Hf isotope composition, suggesting that the TCG incorporated volcanic material from continental large igneous provinces through the erosion of the underlying Hamersley and Fortescue groups

Various organic compounds, including graphitic carbon, can be formed abiotically in hydrothermal systems, such that evidence for early life must necessarily combine geological, morphological and geochemical data to be compelling. Carbonaceous materials (CM) have been isolated from three rock packages of mid to early Archaean age from the Pilbara Craton of Western Australia. This CM has been subjected to a multidisciplinary approach utilising a variety of analytical and observational techniques, in an attempt to establish the occurrence, associations, mineral affinities, historical environments of growth, and the metamorphic/thermal history experienced by what may be some of the earliest, relatively pristine record of 3500 million year old life on this planet. CM isolated from drillcore obtained from the first of these localities, the 3.24 Ga Sulphur Springs volcanic hosted massive sulphide (VHMS) deposit, occurs as isotopically light (δ13C values of −34.0 ‰ to −26.8 δ13C) finely striated, lenticular to banded material emplaced parallel to original sedimentary bedding planes within the fine-grained silicified epiclastic hanging wall sediments. Petrological and transmission electron microscopy (TEM) observations have revealed well-preserved bundles of filamentous and tubular structured microbial remains closely resembling both modern-day and more ancient microbial forms documented from sea floor hydrothermal environments. Total organic carbon (TOC) has a range of <1.0 to 2.3 %, while the thermal maturity (%Ro) of the filamentous bundles points to maximum temperatures since deposition of around 90–100 °C, a factor that has enabled the preservation of their morphology. These results are suggestive of a well-developed Archaean sediment-hosted microbial community, situated within a basinal environment associated with an active centre of seafloor hydrothermal activity. The majority of the CM isolated from drillcore samples of the second locality, the 3.46 Ga Salgash Subgroup, a lower member of the Apex Basalt, also appears as in situ, bedding parallel bands intercalated with foliated altered argillaceous sandstone beds. TOC of the samples ranges from 1.25 to 11.48 %, while carbon content varies from 2.05 to 32.17 %. δ13C results are relatively heavy, varying from -30.4 to -22.5 ‰. Thermal maturity indicators of 10-13 %Ro suggest the CM having been subjected to temperatures greater than normally obtained from processes associated with burial. Electron paramagnetic resonance (EPR) results showed this CM in a highly ordered graphitic state. Optically, the graphite lacks the typical pronounced anisotropy characterising graphites in metamorphic terranes. Graphitisation therefore, is likely the result of rapid heating at very high temperature. HRTEM of this material revealed an extremely high level of molecular ordering contemporaneous with the presence of the C60 fullerene molecules within carbon nanotubes. These forms are a key to the distinction between biologically and abiotically synthesized CM, both by their small size and their resistance to thermal degradation. The occurrence of these carbon forms in terrestrial deposits is rare, and usually associated with wildfires, lighting strike or meteoritic impact. In the case of the Salgash CM, the formation of these molecules and the isotropic graphitised state of the CM is interpreted as a result of emplacement under pressure of very high temperature (komatiitic/ peridotite) lavas. The thermal overprint of the CM by such a high temperature process resulted in the volatilisation of the organic material, destruction of any primary biological morphology and the subsequent reorganisation of the residual CM, resulting in increased molecular ordering. In the third part of the study, CM isolated from drillcore samples of the ca. 3.5 Ga Dresser Formation bedded black chert-barite units, occurs in both dispersed and layered forms, interlayered with fine-grained silica. The intimate association of the CM and silica strongly resembles silicified microbial colonies from active hydrothermal systems, which have been previously proposed as analogues of Archaean hydrothermal sites. Isotopically light δ13C values from -38.2 to -32.1 ‰, and the association of C, H, and N, are highly indicative of a biological origin for the material. Palaeotemperatures calculated from δ18O isotope analysis of quartz chips indicate a depositional temperature for the hydrothermal veins ranging from ~120 °C to ~200 °C. 207Pb-206Pb isotope analyses conducted on pyrites extracted from the interbedded barite units reveal a dual MORB and Erosion mix source for the Pb, which gives an average 207Pb/206Pb age of 3531±42 Ma for the deposit. Ro measurements reveal four distinct CM populations, defined as ACM, A1CM, BCM, and CCM, which represent temperatures ranging from 170 °C to potentially >400 °C. TEM and HRTEM observations of the lower temperature CM population show morphological entities strongly suggestive of microbial remains, including possible cell wall remnants. Higher Ro rank CM commonly fills or coats mineral grains and lacks distinguishable structures, which is consistent with an increased thermal degradation /hydrothermal overprint. The geological setting and mineralogy of the Dresser Formation endorse its formational history as a silica-barite dominated seafloor hydrothermal deposit, most likely analogous to modern “white smokers”. The occurrence of the predominant CM (type ACM) in more or less continuous bands and laminae within the sedimentary rocks suggest an in situ, syndepositional source for the majority of this material, whereas the dispersed nature of type BCM particles indicates a recycled nature. The occurrence of type CCM within fluid inclusions gives an insight into the primary morphology of the non-degraded original microbial cells that may have existed at that time. These observations, combined with the carbon isotopic heterogeneity and fractionations are suggestive of chemosynthetic microbes occupying a seafloor hydrothermal system where rapid silicification at relatively low temperature preserved the CM. Finally, in an effort to further understand the CM structures observed in the rocks of the Dresser Formation in the context of present day microbial colonies in similar environments, a comparative morphological study was conducted using a potential modern analogue derived from an active seafloor hydrothermal environment. Such methodology utilises the standard classification used in biological species identification, which is initially based on visual identification of specific features, whether by the naked eye, light microscopy or electron microscopy. The extant hyperthermophilic microbe Methanocaldococcus jannaschii was cultured under conditions similar to the Archaean seafloor, simulating an increased thermal maturity by artificially induced autoclaving at 100 °C (1 atm) and 132 °C (2 atm). A striking resemblance to the early Archaean forms observed in the Dresser CM was evident in both wall structure and thermal degradation mode of the cultured microbe. Cell disintegration of the cultures occurred at 100 °C marking the limits of life, whereas complete disintegration, deformation and shrinkage of the cells occurred at 132 °C. These comparative observations present as a feasible way of understanding the structural features in CM identified in Archaean sedimentary packages.

The mode of tectonics by which early Archean proto-continents were deformed was investigated in the Pilbara Craton in Western Australia, which has not been substantially tectonically deformed since ~3.2 Ga. The craton consists of a unique dome and keel structure where vertical, low-grade metamorphism basaltic greenstone keels surround large granitic (TTG) domes. The dominant model for 3.5-3.2 Ga deformation in the Pilbara is gravity-driven vertical tectonics, or partial convective overturn in a hot crust. In this model, the granitic bodies rose upward as solid-state diapirs, and the greenstones "sagducted" downward around the granitic bodies. Australian scientists acquired deep seismic reflection data crossing a granitoid-greenstone boundary. Their processing did not image the geologically mapped steep dip of the boundary because standard methods limit the maximum dip. A 37-km section of these data were reprocessed using 2D Kirchhoff prestack depth migration to include vertical dips. The western half of the migrated section images a granitoid dome with weak to no reflectivity that extends deeper than 4 km. The eastern half images 2-3 km of layered volcanic rocks of the Fortescue Group overlying the greenstones. Seismic velocity models created using travel-time tomography suggest a thin weathering layer overlying slightly fractured crystalline rocks. These fractures close within 200-300 m depth, and velocity reaches bedrock speeds consistent with expected values of granitoids to the west and volcanic rocks of the Fortescue Group to the east. The best migrated image contains several reflections with dips (~45-55˚) cross-cutting each other from both directions at the location of the expected granitoid-greenstone boundary. This strongly suggests the presence of steep dips in the upper ~1.5 km but does not provide a definitive image. This inconclusive result is due to strong surface-wave noise, the crooked 2D seismic line, and the 3D nature of the geologic boundary at the seismic line. A very small seismic velocity gradient within the crystalline bedrock limits the maximum depth to which vertical features can be imaged. / Master of Science / The Pilbara craton is one of the few exposed and intact pieces of continents that were formed ~3.2 billion years ago. This research analyzes how these early land masses were deformed. There are two methods by which early land masses evolved—vertical tectonics (a more rudimentary, gravity-driven form of plate movement) or horizontal tectonics (which is closer to modern-day tectonics and requires many stages of deformation). This area has a unique dome-and-keel structure where greenstones (metamorphosed volcanics) are vertically wrapped around large granitic domes. Studying the vertical features of the greenstones will allow us to ascertain how tectonics evolved in the area. A seismic survey was conducted in 2018 in the area. These data were reprocessed to include steep dips to extract the exact location of the steeply dipping boundary between the dome and keel structure at depth. The resulting image contains inconclusive evidence due to the physical limitations of the geology and the sharp bend in the seismic line. Further studies need to be done to determine if the Pilbara Craton was formed by vertical tectonics.

[Truncated abstract] Ecologists are increasingly interested in quantifying local interacting processes and their impacts on spatial vegetation patterns. In arid and semiarid ecosystems, theoretical models (often spatially explicit) of dynamical system behaviour have been used to provide insight into changes in vegetation patterning and productivity triggered by ecological events, such as fire and episodic rainfall. The incorporation of aerial imagery of vegetation patterning into current theoretical model remains a challenge, as few theoretical models may be inferred directly from ecological data, let alone imagery. However, if conclusions drawn from theoretical models were well supported by image data then these models could serve as a basis for improved prediction of complex ecosystem behaviour. The objective of this thesis is therefore to innovate methods for inferring theoretical models of vegetation dynamics from imagery. ... These results demonstrate how an ad hoc inference procedure returns biologically meaningful parameter estimates for a germ-grain model of T. triandra vegetation patterning, with VLSA photography as data. Various aspects of the modelling and inference procedures are discussed in the concluding chapter, including possible future extensions and alternative applications for germ-grain models. I conclude that the state-and-transition model provides an effective exploration of an ecosystem?s dynamics, and complements spatially explicit models designed to test specific ecological mechanisms. Significantly, both types of models may now be inferred from image data through the methodologies I have developed, and can provide an empirical basis to theoretical models of complex vegetation dynamics used in understanding and managing arid (and other) ecological systems.