Province In Australia Research Articles

Graphite as an electrically conductive indicator of ancient crustal-scale fluid flow within mineral systems

Magnetotelluric (MT) imaging results from mineral provinces in Australia and in the United States show an apparent spatial relationship between crustal-scale electrical conductivity anomalies and major magmatic-hydrothermal iron oxide-apatite/iron oxide-copper-gold (IOA-IOCG) deposits. Although these observations have driven substantial interest in the use of MT data to image ancient fluid pathways, the exact cause of these anomalies has been unclear. Here, we interpret the conductors to be the result of graphite precipitation from CO2-rich magmatic fluids during cooling. These fluids would have exsolved from mafic magmas at mid- to lower-crustal depths; saline magmatic fluids that could drive mineralization were likely derived from related, more evolved intrusions at shallower crustal levels. In our model, the conductivity anomalies then mark zones that once were the deep roots of ancient magmatic-hydrothermal mineral systems.

The Formation of Magmatic-Hydrothermal Features in Sn-Mineralized and Barren Tasmanian Intrusions, Southeast Australia: Insights from Quartz Textures, Trace Elements, and Microthermometry

Abstract Tasmania is the most important tin province in Australia, having been endowed with >0.65 Mt Sn. Some granitic intrusions in western Tasmania have distinctive tourmaline- and quartz-rich magmatic-hydrothermal features, whether they are mineralized (e.g., Heemskirk Granite) or barren (Pieman Heads Granite). The Devonian Heemskirk and Pieman Heads plutons crop out on the western coast of Tasmania and are characterized by similar mineralogical and geochemical compositions and ages. The magmatic-hydrothermal textural features include tourmaline patches, tourmaline orbicules, and tourmaline-muscovite veins, as well as miarolitic cavities and quartz-fluorite-sulfide veins in the Heemskirk Granite. Cathodoluminescence (CL) imaging, laser ablation-inductively coupled plasma-mass spectrometry, and microthermometric analyses of quartz have revealed the physicochemical evolution of the magmatic-hydrothermal fluids from which these tourmaline- and quartz-bearing assemblages precipitated. High Ti quartz (20–28 ppm) in tourmaline patches, orbicules, and cavities typically have homogeneous CL-bright intensity, whereas CL-dark fractures have cut and/or offset the CL-bright and -gray domains that characterize low Ti quartz (3.4–8.5 ppm) from the tourmaline veins. The earliest fluid inclusion assemblages in the quartz-tourmaline orbicules and cavities have a salinity range from 3 to 14 wt % NaCl equiv with intermediate density and were probably trapped at lithostatic pressures of 1.57 ± 0.2 kbar and temperatures of 550° to 570°C, suggesting a depth of 5.9 ± 0.8 km. Prolonged depressurization and cooling may have led to the evolution of a brine (~39 wt % NaCl equiv salinity) from the primary magmatic liquid, which formed halite-bearing hypersaline inclusions in the tourmaline orbicules. Continuous pressure decrease explains the intense brittle failure and fluid migration outward from the apical portions of the pluton, where magmatic fluids partially mixed with and were cooled by external meteoric water. These mechanisms triggered the formation of tourmaline-muscovite-quartz veins and local cassiterite-bearing greisens from a moderate-salinity fluid (~12 wt % NaCl equiv) at temperatures of ~300°C and hydrostatic pressures of 120 bars. Retrograde dissolution textures evident from CL-bright quartz cores surrounded by oscillatory growth zones with gray CL response characterize the low Ti (<1 ppm) and high Al (500–1,000 ppm) quartz from the fluorite-sulfide veins that precipitated from a low-salinity (5.7 wt % NaCl equiv) acidic fluid at temperatures of 200° ± 25°C and hydrostatic pressures of <50 bars. High Sb concentrations (up to 80 ppm) in quartz may be an indicator of low-temperature base metal mineralization related to granitic intrusions. Abundant fluid percolation, protracted fractional crystallization, and high tin concentrations in exsolved hydrothermal fluids may explain why the Heemskirk Granite is well endowed in Sn and base metal deposits, whereas the Pieman Heads Granite is barren.

Chemical Composition, U–Th–Pb Age, and Geodynamic Setting of Metavolcanic Filla Series (Rauer Islands, East Antarctica)

An assemblage of mafic granulites (schists), plagiogneisses, and metasedimentary rocks, which is referred to as the Filla Series, is exposed in the Rauer Islands (opposite the eastern coast of the Prydz Bay). The chemistry and Nd isotope composition of the schists, which are interpreted as metavolcanics, are characterized; the results of U–Th–Pb dating (SHRIMP) of zircons from these rocks are presented. The data obtained indicate that the protolith of these rocks crystallized ca. 1500 Ma ago and that the rocks later underwent thermal events at ca. 1000 Ma and 545–515 Ma. The relatively high eNd(t) values, ranging from 2 to 4.5 for most samples, indicate the primitive composition of the mantle source and the limited extent of crustal contamination. The specific chemical composition of these rocks suggests that the Filla Series was formed in a convergent (back-arc(?)) setting with contributions from both plume and lithospheric sources. The apparently heterogeneous rock assemblage may be a product of tectonic interaction between the active continental margin and oceanic plateau. The obtained Early Mesoproterozoic age of the mafic rocks of the Filla Series argues for correlation of the Rauer Islands area with the long-lived Musgrave–Albany–Fraser–Wilkes Proterozoic (super) province in Australia and Antarctica, on the one hand, and the Eastern Ghats Province in India, on the other. The formation of the Early Mesoproterozoic Filla Series suggests that the development of the hypothetical paleocean (its convergent margins) did not terminate during the Paleoproterozoic but continued into the Mesoproterozoic. Correlation with the Musgrave–Albany–Fraser–Wilkes (super) province suggests a shared geological evolution of large crustal blocks, represented by the Prydz Bay coast and the Australian–Antarctic block starting from the Early Mesoproterozoic.

Zero Waste Well – the beneficial use of produced water from CSG projects

Most onshore gas provinces in Australia are in remote locations where it is expensive to bring materials to, and take waste away from, well sites. Importantly, water is not only an input to, and a product of, the drilling, completion, construction and production process, it is also a precious resource. That is why Santos has been working towards the ‘Zero Waste Well’. Historically, separate drilling, completion, construction and operational teams were involved in sourcing and disposing of water without taking a holistic view of the water cycle. By taking a collaborative approach and looking at the complete water cycle, Santos has been able to reduce its water use and eliminate wastewater by reusing all of the produced water in its Queensland coal seam gas upstream activities for beneficial purposes. As part of the Zero Waste Well concept, Santos has identified and implemented a range of initiatives for beneficially reusing produced water. These include stock watering, construction, dust suppression, rehabilitation, and drilling and completion activities. One of the most exciting innovations is to beneficially reuse produced water for localised irrigation. This avoids or minimises the need for large centralised water gathering systems and large static centralised water storages and treatment plants. This also minimises the environmental footprint, energy intensity, carbon emissions and brine wastes from Santos’ activities. Localised irrigation not only reduces construction and operating costs, and engineering design and construction timeframes for Santos, it provides a valuable pasture irrigation source for local landholders.

The Structural Evolution of the North West Shelf: a Thermomechanical Modeling Approach Using Stratified Lithospheric Rheologies and Surface Processes

The processes involved in the structural and stratigraphic evolution of the North West Shelf (NWS), one of the most productive and prospective hydrocarbon provinces in Australia, remain controversial. The complex structural characteristics of the NWS include large-scale extensional detachments, difference between amounts of crustal and lithospheric extension and prolonged episodes of thermal sagging after rifting episodes. It has been proposed that the succession of different extensional style mechanisms (Cambrian detachment faulting, broadly distributed Permo-Carboniferous extension and Late Triassic to Early Cretaceous localised rift development) are best described in terms of variation in deformation response of a lithosphere that has strengthened from one extensional episode to the next. However, previous models invoking large-scale detachments fail to explain changes in extensional styles and over-estimate the structural importance of relatively local detachments (e.g. Scholl Island Fault). Here, we hypothesize that an initially weak lithosphere would distribute deformation by ductile flow within the lower crust and that the interaction between crustal flow, thermal-evolution and sediment loading/unloading could explain some of the structural complexities recorded by the NWS. To test this hypothesis we run a series of fully coupled 3D thermo-mechanical numerical experiments that include realistic thermal and mechanical properties, as well as surface processes (erosion, sediments transport and sedimentation). This modeling approach aims to provide insights into the thermal and structural history of the NWS, and a better understanding of the complex interactions between tectonics and surface processes on the margin scale.

First data on U-Pb age of mafic dyke in the Mirny Station area (Pravdy Coast, East Antarctica)

We firstly report a SHRIMP zircon age on a post-metamorphic mafic dyke from the Mirny Station area in Pravdy Coast which is underlain by ca 1000 Ma metamorphic rocks that experienced thermal and magmatic activities at ca 500 Ma. A concordant age of 507 ± 6 Mа for zircon from post-metamorphic dolerite has been obtained. The analyzed grains display the REE and other trace element concentrations corresponding well to zircons from typical dolerites worldwide (e.g., low Hf, Y), which allows interpretation of the obtained date as dolerite dyke crystallization. Geochemical and Sr–Nd isotopic data on the dyke rocks show that these rocks have high-Ti, P concentrations, are enriched in other HFSE and also REE and have low εNd(500) of −13.2, and high 87Sr/86Sr(i) of 0.71206. These features are consistent with derivation from a strongly enriched subcontinental mantle source. Chemical and isotopic compositions of the dyke rocks correspond to those known from the continental flood basalt provinces, in particular to the Cambrian Antrim extensional Large Igneous Province in Australia. This magmatic event is thought to reflect an extension episode between East Antarctica, Australia, and Greater India.

A curious case of agreement between conventional thermobarometry and phase equilibria modelling in granulites: New constraints on P–T estimates in the Antarctica segment of the Musgrave–Albany–Fraser–Wilkes Orogen

AbstractThe Windmill Islands region in Wilkes Land, east Antarctica, preserves granulite facies metamorphic mineral assemblages that yield seemingly comparable P–T estimates from conventional thermobarometry and mineral equilibria modelling. This is uncommon in granulite facies terranes, where conventional thermobarometry and phase equilibria modelling generally produce conflicting P–T estimates because peak mineral compositions tend to be modified by retrograde diffusion processes. In situ U–Pb monazite geochronology and calculated metamorphic phase diagrams show that the Windmill Islands experienced two phases of high thermal gradient metamorphism during the Mesoproterozoic. The first phase of metamorphism is recorded by monazite ages in two widely separated samples and occurred at c. 1,305 Ma. This event was regional in extent, involved crustally derived magmatism and reached conditions of ~3.2–5 kbar and 690–770°C corresponding to very high thermal gradients of >150°C/kbar. The elevated thermal regime is interpreted to reflect a period of extension or increased extension in a back‐arc setting that existed prior to c. 1,330 Ma. The first metamorphic event was overprinted by granulite facies metamorphism at c. 1,180 Ma that was coeval with the intrusion of charnockite. This event involved peak temperatures of ~840–850°C and pressures of ~4–5 kbar. A phase of granitic magmatism at c. 1,250–1,210 Ma, prior to the intrusion of the charnockite, is interpreted to reflect a phase of compression within an overall back‐arc setting. Existing conventional thermobarometry suggests conditions of ~4 kbar and 750°C for M1 and 4–7 kbar and 750–900°C for M2. The apparent similarities between the phase equilibria modelling and existing conventional thermobarometry may suggest either that the terrane cooled relatively quickly, or that the P–T ranges obtained from conventional thermobarometry are sufficiently imprecise that they cover the range of P–T conditions obtained in this study. However, without phase equilibria modelling, the veracity of existing conventional P–T estimates cannot be evaluated. The calculated phase diagrams from this study allow the direct comparison of P–T conditions in the Windmill Islands with phase equilibria models from other regions in the Musgrave–Albany–Fraser–Wilkes Orogen. This shows that the metamorphic evolution of the Wilkes Land region is very similar to that of the eastern Albany–Fraser Orogen and Musgrave Province in Australia, and further demonstrates the remarkable consistency in the timing of metamorphism and the thermal gradients along the ~5,000 km strike length of this system.

Comment 1 on ‘Agricultural Innovation’ by Alston and Pardey

As expected, in spite of a severe space constraint, Alston and Pardey's (2016) review of the contribution of Australian economists to understanding the impact of research on the welfare of farmers and others and its implications for science policy picks up on most of the key issues. One reason for measuring the impact of research is to demonstrate that it is a good use of scarce resources – an accountability perspective which dominates the Alston and Pardey paper. Research evaluation, whether ex ante or ex post, can also contribute to the development of research programs which have stronger impacts on the sector. I want to point out the contribution Australian economists, especially those in State Departments of Agriculture, have made in working closely with scientists with potential benefits not only to research planning and evaluation but also to the adoption of new technologies. In the online material (Appendix 2), Alston and Pardey note the gains from scientists and economists sharing the tea room, but perhaps this contribution is understated because little of this work appears in the scientific literature. I cannot give empirical evidence for these efficiency gains, but in my experience, scientists in State Departments are more likely to understand the notion of a plausible causal pathway from the research resources available to them and final outcomes observed on farms and the counterfactual, than scientists in universities or CSIRO. This collaboration with scientists in research processes has been strongest in the WA, Victorian, QLD and NSW Departments. These efforts have been strongly encouraged by economists in the Grains Research and Development Corporation and the Australian Centre for International Agricultural Research. There is no space to address all these issues here. However, estimating the total gains in economic welfare is the starting point for making judgements about contributions by research, allowing one to compare benefits of agricultural innovation to other objectives science managers might pursue like poverty alleviation and women's empowerment. It is also the starting point for making judgements about the importance of capacity building activities relative to knowledge discovery processes through experiments and other uses of research funds. Alston and Pardey suggested that poor communication of its benefits might partly explain the lack of support for agricultural R&D. A commitment to carefully measuring and explaining how new technologies impact on farm plans and profit would seem to be an essential component of any improved communication strategy to increase innovation and adoption. Perhaps another dimension of the communication issue may be that policy makers outside agriculture do not appreciate the breadth of agricultural R&D which underlies better environmental, human health and animal welfare outcomes and is the scientific basis for protecting Australia's interests in areas like phytosanitary trade regulation and clean, green and animal welfare ‘certification’ processes. Perhaps policy makers interpret agricultural R&D to mean traditional farm production technology R&D, dismissed as the province of Australia's rural R&D corporations. Alston and Parley's paper begs the question as to why Australians have made such a large contribution in this area of science policy research evaluation. Perhaps because farmers were supporting research through levies as far back as 1936, economists were confronted with questions about the returns from such investments and their distribution much earlier than in other countries, an interesting question for further discussion. Finally, Alston and Pardey note the slowdown in the growth of multifactor productivity (MFP) in Australian agriculture in common with other countries. According to Hughes et al. (2011), from 1978 to 2008, climate-adjusted MFP for broadacre cropping in Australia grew at an annual rate of 1.53%, but since 2000, it grew at a rate of only 0.24%. There seems little reason to expect MFP growth to return to 1.5–2.0% per year unless there is a large increase in R&D over several decades.

Geogenic Factors as Drivers of Microbial Community Diversity in Soils Overlying Polymetallic Deposits.

This study shows that the geogenic factors landform, lithology, and underlying mineral deposits (expressed by elevated metal concentrations in overlying soils) are key drivers of microbial community diversity in naturally metal-rich Australian soils with different land uses, i.e., agriculture versus natural bushland. One hundred sixty-eight soil samples were obtained from two metal-rich provinces in Australia, i.e., the Fifield Au-Pt field (New South Wales) and the Hillside Cu-Au-U rare-earth-element (REE) deposit (South Australia). Soils were analyzed using three-domain multiplex terminal-restriction-fragment-length-polymorphism (M-TRFLP) and PhyloChip microarrays. Geogenic factors were determined using field-mapping techniques and analyses of >50 geochemical parameters. At Fifield, microbial communities differed significantly with geogenic factors and equally with land use (P < 0.05). At Hillside, communities in surface soils (0.03- to 0.2-m depth) differed significantly with landform and land use (P < 0.05). Communities in deeper soils (>0.2 m) differed significantly with lithology and mineral deposit (P < 0.05). Across both sites, elevated metal contents in soils overlying mineral deposits were selective for a range of bacterial taxa, most importantly Acidobacteria, Bacilli, Betaproteobacteria, and Epsilonproteobacteria. In conclusion, long-term geogenic factors can be just as important as land use in determining soil microbial community diversity.

U-Pb geochronology of 1.1 Ga diabase in the southwestern United States: Testing models for the origin of a post-Grenville large igneous province

Late Mesoproterozoic mafic magmatism in the southwestern U.S. diabase province is expressed as diabase dikes, sills, sheets, and flows. Previous radiometric ages range from 1140 Ma to 1040 Ma. We used high-precision thermal ionization mass spectrometry to date baddeleyite in diabase from four localities in Arizona to obtain 206 Pb/ 238 U dates of 1080 ± 2 Ma, 1080 ± 3 Ma, 1088 ± 3 Ma, and 1094 ± 2 Ma. We also obtained single-crystal laser-ablation and ion microprobe ages on zircons from two localities in New Mexico that indicate a wider geographic extent of this diabase province. The samples have SiO 2 ranging from 46.6 to 50.1 wt%, Mg# from 67 to 83, and e Nd ranging from +4.7 to -1.4. A compilation of previously published ages of silicic rocks in the same age range suggests that mantle-derived magma induced crustal anatexis resulting in silicic magmatism, and this bimodal event forms a large igneous province that stretches 1500 km from east to west and 500–1000 km from north to south. Because some of the ca. 1.1 Ga plutonism extends outside the United States into northern Mexico, we suggest renaming this event as the Southwestern Laurentia large igneous province (SWLLIP). Magmatism in the province from 1094 to 1080 Ma occurred largely after the end of the Grenville orogeny. Two models that are not mutually exclusive are proposed: (1) lithospheric delamination following the Grenville collision; and (2) arrival of a mantle plume beneath south-central Laurentia, which spread beneath the lithosphere, with a northward-heading portion causing Keweenawan magmatism (at the boundary with the Superior craton), and a southward-heading portion creating the Southwestern Laurentia large igneous province. Other large igneous provinces have been previously correlated to these events, but the 1075 Ma Warakurna large igneous province in Australia is too young, and the 1110 Ma events in the Amazonian Congo and Kalahari cratons are too old.

How to design a sustainable heavy industrial estate

The Mid West of Western Australia, south of the Pilbara, is developing as the next major mineral province in Australia. The province will be served by a new port at Oakajee and will be backed by a 4000 + ha greenfield industrial area. LandCorp, the State Government's land development agency intends that the Oakajee Industrial Estate (OIE) will be a “sustainable industrial estate”.This paper describes the design process used to produce a flexible and adaptable layout of the estate to maximise use of renewable energy and minimise carbon emissions. The design and planning was complex because it had to anticipate a 50 year development program. Issues addressed included site characteristics and context, land allocation to optimise energy efficiency, embedding a multi-user co/tri-generation system in the middle of the estate, identify and estimating the production of energy from on-site and regional sources of renewable energy, options for reducing greenhouse emissions, waste reduction and reuse; and issues relating to the governance and management of the estate that will enable these site innovations to occur.

Continental flood basalts of the Huashan Group, northern margin of the Yangtze block – implications for the breakup of Rodinia

It is generally accepted that Neoproterozoic extension and dispersal of the supercontinent Rodinia was associated with mantle plume or superplume activities. However, plume-generated contemporaneous continental flood basalts (CFBs) have rarely been identified. In this study, we present geochronological and geochemical evidence for the basalts from the Liufangzui Formation of the Huashan Group in the Dahongshan region of east-central China. A representative sample yields a SHRIMP U–Pb zircon age of 824 ± 9 Ma, interpreted as the crystallization age of the rocks. Geochemically, these basalts belong to the subalkaline tholeiite series and display slight enrichments in light rare earth elements (LREE) and varying degrees of deficiency of high field strength elements (HFSE) such as Nb, Ta, and Ti. This pattern is very similar to that of CFBs from the Bikou Group and Tiechuanshan Formation in the northwestern Yangtze block in China and Siberia in Russia. The basaltic magmas underwent partially-fractional crystallization during ascent, but were not intensely influenced by crustal contamination. The characteristic element ratios and negative Hf isotopic analyses (ϵHf(t) = −6.6–2.6) in zircons indicate that the parental magmas of the basalts might have been derived from an enriched lithospheric mantle rather than from the depleted mantle such as normal mid-ocean ridge basalts (N-MORBs). The geochemical signatures and regional geological characteristics show that these basalts were formed along intraplate continental rifts rather than in island arcs or ocean basins. Considering the coeval basic volcanic rocks in South China, we propose that these Huashan Group basalts represent the remnants of plume-generated CFBs and have close spatiotemporal ties with a coeval basic igneous province in Australia. Our results support the Neoproterozoic location of the South China block adjacent to southeastern Australia in the reconstruction model of the supercontinent Rodinia.

Revisiting petroleum systems in the Gippsland Basin using new geochemical data

The Gippsland Basin is one of the most prolific petroleum provinces in Australia, yet the understanding of source, migration and secondary alteration of petroleum is often based on data and concepts that have been developed decades ago. For instance, the Gippsland Basin is commonly cited as an explicit example of a province dominated by oil from coal, yet there is no literature using molecular and isotope geochemistry explicitly demonstrating that generation and expulsion has been from the coal seams and not the intervening carbonaceous mudstones. In this study we will present insights from the evaluation of quantitative analyses of aromatic hydrocarbons, which will be evaluated together with low molecular weight hydrocarbon distributions from whole oil gas chromatography and aliphatic biomarker distributions of the oils. Oils are commonly incrementors of different charge events, and hence extending molecular and isotopic information from a wide molecular weight range offers a more detailed insight into the charge history of an oil field. Oil-bearing fluid inclusions are additional archives that hold keys to the fill history of petroleum reservoirs, and this contribution will also present new data on the distribution and composition of palaeo-oils trapped in fluid inclusions. Lastly, examples will be presented of how modern tools for analysis such as compound specific isotopic analysis (CSIA) of n-alkanes and isoprenoids as well as how understanding relationships between organic facies and source rock kinetics can contribute to refining our understanding of petroleum systems in the Gippsland Basin.

Review of registration requirements for new part-time doctors in New Zealand, Australia, the United Kingdom, Ireland and Canada

By the time medical students graduate many wish to work part-time while accommodating other lifestyle interests. To review flexibility of medical registration requirements for provisional registrants in New Zealand, Australia, the United Kingdom, Ireland and Canada. Internet-based review of registration bodies of each country, and each state or province in Australia and Canada, supplemented by emails and phone calls seeking clarification of missing or obscure information. Data from 20 regions were examined. Many similarities were found between study countries in their approaches to the registration of new doctors, although there are some regional differences. Most regions (65%) have a provisional registration period of one year. Extending this period was possible in 91% of regions. Part-time options were possible in 75% of regions. All regions required trainees to work in approved practice settings. Only the UK provided comprehensive documentation of their requirements in an accessible format and clearly explaining the options for part-time work. Australia appeared to be more flexible than other countries with respect to part- and full-time work requirements. All countries need to examine their registration requirements to introduce more flexibility wherever possible, as a strategy for addressing workforce shortages.

Australian Jurassic sedimentary and fossil successions: current work and future prospects for marine and non-marine correlationThis is a contribution to IGCP 506: Marine/Non-marine Jurassic correlation.

Strata of Jurassic age occur extensively across onshore Australia, but they are predominantly of non-marine origin. Marine Jurassic strata have only limited onshore exposure in northwestern and central-western Australia, with thick marine sequences lying offshore on the North West Shelf. The richest petroleum province in Australia is located at the shelf's southern end, where the Dingo Claystone represents an important source rock for oil and gas. By and large, non-marine deposits, including economic coals, are distributed in the eastern states. Jurassic stage boundaries, in the main, are poorly constrained with respect to the Australian sedimentary succession. New work on microfossils, plants, fish, and zircon dating is providing a basis for improved correlation across Australian basins, with overseas successions, and recent international IUGS geologic timescales.

Shallow Geophysical and Hyrogeological Studies to Characterise Palaeochannel Properties, A Case Study From Tanami Desert, NT

Palaeochannels are typical geomorphic features representing drainage streams or rivers, which were flowing either during the past time and now stand buried or shifted due to tectonic or geomorphological processes. They often contain considerable thicknesses of sediment with elements which have been dated from the Mesozoic through to the late Cainozoic. These sediments are known to host, or act as pathfinders, to economic mineralization, and are an important source of potable groundwater, particularly in remote areas. Located about 600km northwest of Alice Springs, the Tanami region of the Northern Territory is an emerging gold province in Australia. Although not genetically related, some of the gold deposits are located on the margins of palaeochannels. Outcrop in these areas is sparse and bedrock is generally covered by in situ and transported regolith materials, that at places may reach more than 300m. Interest from industry and extensive drilling activity in the region has provided us with a natural laboratory to apply a multi-disciplinary approach for studying regolith properties and processes. As part of the research activities of Co-operative Research Centre for Landscape Environments and Mineral Exploration (CRC-LEME), we have carried out ground transient electromagnetic (TEM) and down-hole EM measurements as well as hydrogeochemical sampling of the open drill holes at the Titania mineral prospect. Apart from identifying possible locations of mineralisation, these studies have clearly delineated the structure of the palaeochannel, the character of the fill and the properties of the groundwater. A detailed discussion on the results will be presented.

The Kalkarindji continental flood basalt province: A new Cambrian large igneous province in Australia with possible links to faunal extinctions

Extensive basaltic volcanism (>106 km 2 ) occurred across northern and western-central Australia during Cambrian time. The basalts are geochemically distinctive, having unusually uniform elevated incompatible element signatures (high Th/U, La/Sm, Rb/Ba) that are atypical of most other continental flood basalt provinces. Individual volcanic and intrusive suites previously assigned to local stratigraphic units are shown to share a common parental magma. This vast Cambrian igneous province is here named the Kalkarindji continental flood basalt province, Australia's oldest and largest Phanerozoic large igneous province. High-precision 4 0 Ar/ 3 9 Ar analyses of plagioclase feldspar separates from basalt flows yield ages of 508 ′ 2 Ma and 505 ′ 2 Ma (2σ), indistinguishable from previous U-Pb zircon ages for related dolerites. These ages indicate that basaltic volcanism coincided with the Early-Middle Cambrian boundary and suggest a temporal link between eruption of the Kalkarindji basalts and the end-Early Cambrian (early Toyonian) faunal mass extinction event.

PETROLEUM POTENTIAL OF THE CEDUNA SUB-BASIN: IMPACT OF GNARLYKNOTS–1A

The Ceduna Sub-basin, located in the eastern Bight Basin, is one of the few frontier deepwater provinces in Australia whose hydrocarbon potential remains largely untested. The sediments of the sub-basin span an area of over 95,000 km2—comparable to the combined area of the Exmouth, Barrow and Dampier sub-basins on Australia’s North West Shelf. Prior to 2003, exploration wells had been drilled only on the present day shelf area of the sub-basin. The recent Gnarlyknots–1A well, drilled in May 2003 by the Woodside operated joint venture in EPP29, has provided the first calibration point in the under-explored deepwater area of the sub-basin.The well was the culmination of a basin analysis project that integrated results from prior drilling in adjacent areas, existing seismic surveys, regional gravity and magnetics interpretations, and a newly acquired 16,000 line km 2D seismic survey. Individual play elements of reservoir, seal, and hydrocarbon charge were analysed and combined to form play maps for key stratigraphic intervals. The Gnarlyknots prospect was chosen from more than 40 leads as the best location to test multiple play levels in an area interpreted pre-drill to be favourable for reservoir, seal, and charge.Gnarlyknots–1A confirmed the presence of several favourable play elements but failed to encounter commercial hydrocarbons. Excellent quality sandstone reservoirs, marine shale top seals and thermogenic hydrocarbon shows—indicating the presence of a hydrocarbon source rock in a mature kitchen area downdip—were all encountered in the well. The failure of the well is attributed to the absence of fault seal on the updip bounding fault of the drilled hanging wall structure. The implications of this well result for the prospectivity of the Ceduna Sub-basin have been analysed, and provide encouragement for Woodside to pursue future exploration programs in the region.

Warakurna large igneous province: A new Mesoproterozoic large igneous province in west-central Australia

Research Article| February 01, 2004 Warakurna large igneous province: A new Mesoproterozoic large igneous province in west-central Australia Michael T.D. Wingate; Michael T.D. Wingate 1Tectonics Special Research Centre, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Search for other works by this author on: GSW Google Scholar Franco Pirajno; Franco Pirajno 2Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia Search for other works by this author on: GSW Google Scholar Paul A. Morris Paul A. Morris 2Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Michael T.D. Wingate 1Tectonics Special Research Centre, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009, Australia Franco Pirajno 2Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia Paul A. Morris 2Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia Publisher: Geological Society of America Received: 03 Sep 2003 Revision Received: 20 Oct 2003 Accepted: 24 Oct 2003 First Online: 03 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2004) 32 (2): 105–108. https://doi.org/10.1130/G20171.1 Article history Received: 03 Sep 2003 Revision Received: 20 Oct 2003 Accepted: 24 Oct 2003 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael T.D. Wingate, Franco Pirajno, Paul A. Morris; Warakurna large igneous province: A new Mesoproterozoic large igneous province in west-central Australia. Geology 2004;; 32 (2): 105–108. doi: https://doi.org/10.1130/G20171.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Coeval mafic igneous rocks emplaced rapidly over ∼1.5 × 106 km2 in western and central Australia represent the erosional remnants of a late Mesoproterozoic large igneous province, named here the Warakurna large igneous province. SHRIMP U-Pb dating of rocks separated by as much as 1500 km indicates that the main episode of magmatism occurred between 1078 and ca. 1070 Ma. The Warakurna large igneous province includes layered mafic- ultramafic intrusions and mafic to felsic volcanic rocks and dikes in central Australia, a 1000-km-long mafic sill province in Western Australia, and several swarms of mafic dikes. The large areal extent and short duration imply emplacement above a mantle-plume head. Despite their wide separation, the mafic rocks have similar mid-oceanic-ridge basalt–normalized trace element patterns and rare earth element characteristics. West-directed paleocurrents, westward-radiating dike swarms, and the occurrence of high-Mg rocks indicate that the center of the plume head was located beneath central Australia. Other late Mesoproterozoic large igneous provinces, in the Laurentia and Kalahari cratons, appear to be significantly older than the Warakurna large igneous province in Australia and thus are unlikely to be related to the same mantle-plume head. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The geology and genesis of high-grade hematite iron ore deposits

This paper presents a first summary of results of an ongoing study, started some two years ago, of high-grade iron ore deposits in South Africa, India and Brazil, including a comparison with the rather well-studied deposits of the Hamersley Province in Australia. Large, high-grade hematite iron ore bodies hosted by Precambrian banded iron formations are the world's most important source of iron ore. Despite their great economic importance, the origin of these deposits has remained rather enigmatic. Results of preliminary investigations into the geological setting, petrography and geochemistry of BIF-hosted high-grade hematite iron ore deposits in South Africa, India, Western Australia and Brazil reveal distinct similarities, suggest ing a very similar mode of hydrothermal and supergene-modified hydrothermal origin for most BIF-hosted highgrade hematite ore deposits. Differences between the deposits of this type are largely the result of varying intensities of supergene modification in Late Cretaceous to Tertiary times. Notable exceptions are the deposits in the Griqualand West region of South Africa, including the giant Sishen deposit, that are regarded to be of ancient supergene origin.