John L Keeling

... at Kambalda in 1966, Western Australia has been a major world producer of nickel. The deposits are all hosted by komatiitic rocks, and represent the only significant resources of sulfide Ni in Australia, although small deposits are known elsewhere (eg Avebury, Tasmania). ...

Abstract Dolomite can form the major mineral component of marlstones, and limestones and is an important sink for Magnesium in the different geogene environments such as oceans. The Mg-distribution in the Earth crust and mantle is partly controlled by dolomite in various crystal structures. The genesis of dolomite record important geochemical and environmental processes in the Earth's element cycle. The human society seeks dolomite as an ideal place for CO2-storage, and it is used for management and maintenance of the environment, and in various industrial processes. Dolomite hosts several important ore deposits and major fossil fuel occurrences. The review brings together new advances and insights from recent studies on dolomite structure, geological genesis, laboratory synthesis, and applications. In the mantle, dolomite may adapt to increasing pressure by structural rearrangement and undergoes crystal phase transitions. At present, four high-pressure polymorphs have been identified. The phase transitions allow dolomite to survive subduction into the mantle, possibly into the transition zone, but stability is not fully predictable and is influenced by factors that include initial degree of cation ordering in dolomite and Fe and Mn substitution for Mg in the dolomite crystal lattice. The presence of Fe and Mn is influenced by the environment of dolomite formation. The key factors controlling formation of dolomite, including transition or recrystallization from precursor high-Mg calcite or proto-dolomite, at low temperatures remain ambiguous. Sulfate-reducing bacteria, methanogens, and aerobic bacteria, the exudates or relevant extracellular polymeric substances, fluctuating environmental conditions, and the negatively charged surfaces of clay minerals all can mediate high-Mg calcite/proto-dolomite formation at low temperature. As for secondary dolomite, formed by Mg2+ replacement of Ca2+ in carbonate minerals, several models have been proposed and widely adopted, including: near-surface dolomitization, burial dolomitization, and hydrothermal dolomitization. The formation of massive deposits of dolomite in marine sediments probably involves multiple dolomitization processes. Yet the “dolomite problem” remains enigmatic. Mg isotope analysis, an emerging technology, offers a new approach to further investigate the genesis of dolomite. In the laboratory, synthesis of dolomite at low temperature has yet to be achieved. Fundamental scientific research on dolomite is expected to inform the sustainable use of dolomite resources. Traditional uses of dolomite typically in construction materials, refractory, and flux continue. Now, the use of dolomite and its calcined products is being expanded into environmental protection, soil improvement, thermochemical energy storage and biomedical materials.

South Australia found as the result of follow up of airborne spectral targets. They add to the growing list of newly discovered kimberlite bodies within the Flinders Ranges and Nackara Arc exploration project areas of Flinders Diamonds Ltd (FDL). Between September 2004 and June 2005, FDL discovered 37 new kimberlites through the use of airborne and ground magnetic surveys (Wills, 2005a). Integration of hyperspectral surveys with the proven technique of low-level magnetics offers a means of locating and prioritising shallow kimberlite targets, including those with a subtle magnetic anomaly.

Abstract Halloysite nanotubes (Hal) with unique nanosized tubular structures are promising nanoclay for potential applications as reinforcement fillers, anticorrosion coatings, as well as drug carriers, and adsorbents. Thus far, previous studies on acid treatment of Hal have focused only on Hal from a single source under various conditions of acid strength, temperature, and treatment duration. This study is the first to characterize and compare the effects of acid treatment on three types of Hal (Dragonite (DG), HalloPure (HP), and Camel Lake (CLA)) sourced from different geological deposits, and the results considered in terms of their suitability for various applications. Analyses revealed porous tubular structure with an increased lumen diameter of up to 78% and improved surface area from 54 m2g-1 to 160 m2g-1 on acid-treated CLA (acid-CLA). By comparison, lumen diameters were reported to increase by only 46% and 52% for acid-DG and acid-HP, respectively. Despite that, crystallinity of acid-DG decreased the most, from 64.5% to 59.4%, with a high recorded surface area of 229 m2g-1, whereas crystallinity of acid-HP decreased the least from 62.5% to 61.1% with a surface area of 121 m2g-1. Therefore, results obtained support the hypothesis that various Hal can be affected differently by acid treatment, and not all types of Hal are suitable for acid treatment, especially for those intended for use as reinforcement materials.

Abstract The processes leading to the formation of beach placer deposits generally begin inland and terminate at the coast, including source rocks being weathered, eroded and then transported by streams and rivers to the coast, where the sediments are deposited in a variety of coastal environments. The coastal sediments are reworked by the action of waves, tides, longshore currents and wind, which are effective processes for sorting the mineral grains based on differences in their size and density, resulting in laminated or lens-shaped packages of sediments up to tens of meters thick that are rich in heavy minerals. Detailed studies of sedimentary basins, as well as peripheral (paleo-)valleys that drained sediment source areas, are important tools in the exploration for heavy mineral resources. Knowledge of the (paleo-)basin, associated valley architecture and the source of heavy minerals concentrated in the shorelines and valleys are useful guides to the potential for, and location of, economic deposits. Evidence from sedimentology can be combined with that from other geological and geophysical characteristics to arrive at a general reconstruction of basin and paleovalley architecture and depositional environments. Complex paleogeography of the shorelines can influence or determine the sites of heavy mineral concentration. Heavy mineral sands tend to concentrate in certain shoreline settings during storm activity. Repeated storm erosion and reworking over centuries (e.g., the southeastern coast of Australia) or millennia (e.g., the Eucla and Murray Basins of Australia) can progressively enrich heavy mineral sand deposits. Preservation of these deposits over a geological timeframe of millions of years can ensue through subsidence of coastal sediments, and during sea-level change that results in either shorelines migrating inland (marine transgression) or seaward (marine regression), potentially burying or stranding earlier deposits or reworking them to form younger deposits. Refinements in remote sensing and geophysical techniques, data processing, sedimentology and computer-aided interpretations provide effective, economic and efficient methods for modeling coastal reconstructions and for exploring provinces and terrains prospective for heavy mineral sand deposits. Landscape topography analysis, combined with geophysical methods that can resolve physical property contrasts between the shoreline sediments and underlying sequences, are increasingly used in mineral exploration to locate and to reconstruct paleoshorelines and paleovalleys. Australia has modern and ancient beach-placer deposits, both of which show many similar geologic features. The formation of these heavy mineral deposits provides one of the best examples of applying knowledge of modern systems (e.g., the west and east coasts of Australia) as an analogue to interpret and understand the geology and form of ancient deposits (e.g., the Eucla and Murray Basins of southern Australia). This study provides descriptive and exploration models of Australia’s heavy mineral sand deposits formed in coastal environments, which can be applied to similar settings worldwide.

A method of infrared (IR) analysis for quantitative determination of tubular halloysite in mixtures with kaolinite was investigated for drill hole samples collected during an assessment of paper-coating kaolin resources at the Mount Hope Kaolin Deposit, Eyre Peninsula, South Australia. Tubular, dehydrated halloysite from the deposit does not readily intercalate formamide, and the proportion of tubes in <2 μm size-fractions was determined initially from scanning electron micrographs. For samples showing a range of tube contents, a strong correlation between IR spectral response and counts of halloysite tubes was established using partial leastsquares analysis. This provided a rapid technique suitable for routine determination of tubular halloysite in samples from the Mount Hope deposit. Although the universality of the method remains to be tested, it offers an alternative approach to other analytical techniques for assessment of kaolin deposits where the presence of halloysite is ...

Halloysite with tubular morphology is formed in a wide range of geological environments from the alteration of various rock types. Intrusive acidic coarse-grained rocks, such as granites, pegmatites and anorthosite, with large potash and sodic feldspars contents, are subsequently altered to kaolinite, halloysite and other clay minerals by weathering or shallow hydrothermal fluid activity. Processing to separate the halloysite-kaolinite fraction from the altered host rock provides a product which can be used as a paper filler and in ceramics and fibreglass, among other uses, with various deposits in Brazil, China, Thailand and elsewhere. In the Kerikeri-Matauri Bay district of Northland, North Island, New Zealand, volcanic alkali rhyolite was extruded as domes and cooled rapidly with fine-grained feldspar subsequently altered to halloysite. The IMERYS plant in Matauri Bay separates the clay from the quartz-cristobalite matrix with an ∼20% yield of halloysite. The principal market is ...

Abstract—Mining operations during the early 1990s at Uley Graphite Mine near Port Lincoln on southern Eyre Peninsula, South Australia, uncovered abundant nontronite veins in deeply weathered granulite facies schist, gneiss, and amphibolite of Palaeoproterozoic age. Two types of nontronite are present: a bright yellowish-green clay (NAu-1) distributed as veinlets and diffuse alteration zones within kaolinized schist and gneiss, and a massive to earthy, dark-brown clay (NAu-2) infilling fracture networks mainly in amphibolite or basic granulite. The nontronites are the product of low-temperature hydrothermal alteration of primary minerals, biotite, and amphibole. The principal chemical difference between NAu-1 and NAu-2 is a higher alumina content in NAu-1, which was either inherited during hydrothermal alteration of biotite in the host rock or acquired through recrystallization of nontronite during subsequent weathering and associated kaolinization. Sufficient bulk samples of both NA...

PIRSA through CRC LEME aims to develop improved methods to detect mineralisation buried by sediment cover. This requires knowledge of likely metal transfer mechanisms, and modification and optimisation of detection technologies to suit the particular environment being targeted by mineral exploration. The following is a brief summary of possible metal transfer mechanisms through transported cover (after Aspandiar, 2005) and geochemical techniques currently under investigation in the Curnamona mineral exploration project. TRANSPORT MECHANISMS INCLUDE: • Water table fluctuation • Vegetation • Gas migration • Dilatancy pumping • Microbial activity • Bioturbation • Redox anisotropy • Diffusion • Thermal convection in groundwater • Evaporation and capillarity • Barometric pumping EXPLORATION APPROACHES INCLUDE: • Soil sampling (partial leach, total leach) • Targeted sampling media and depth (e.g. calcrete/ferricrete/silcrete) • Vegetation sampling • Soil gas (SDP) • Geophysical (electro-m...

Shear-hosted Cu-Au deposits in the Moonta mining district on northern Yorke Peninsula, South Australia, were an important source of Cu from 1860 to 1920, making a major contribution to the 355,000 tonnes of Cu and 2 tonnes of Au recorded for the Moonta-Wallaroo mining district (Conor 1996). The Moonta orebodies are narrow hydrothermal vein deposits largely confined within shear zones and fractures in Palaeoproterozoic Moonta Porphyry (1760 Ma). Copper mineralisation was introduced in fluids emanating from Hiltaba Suite granite emplaced at depth at about 1600 Ma.

Timing and distribution of alteration minerals relative to Cu mineralisation were determined and data collected on the geochemical dispersion of ore-associated
elements, particularly in the 5-15 m thick cover of Quaternary sediments. This paper reviews data from earlier work on alteration mineralogy and speculates on the role of acid sulphate weathering in geochemical dispersion processes and certain mineralogical changes observed in the host porphyry and sedimentary regolith. The aim is to identify changes in the host rock and younger cover that reflect the presence of nearby mineralisation.

Minor celadonite is associated with extensive nontronite alteration in deeply weathered graphitic schist and gneiss at the Uley graphite mine, 18 km southwest of Port Lincoln, and is a co-dominant alteration mineral, with silica, iron and manganese oxides, in sheared graphitic schist in coastal cliffs at Sleaford Bay, 7.3 km south of the Uley mine. The bluish-green clay mica was characterised using X-ray diffraction (XRD), chemical analysis and electron microscopy. Selected size fractions were dated by K-Ar method. Celadonite, replaces biotite and infills veinlets as crystalline micro-laths to 10 μm long by 1 μm wide and ~0.1 μm thick, of ferroceladonite composition K0.82Na0.03 (Fe 3+ 1.08Al0.06Fe 2+ 0.20Mg0.55) Si4O9.9 (OH)1.98 (H2O)0.12. At Uley mine, celadonite is partially replaced by kaolinite. The timing of celadonite formation at Sleaford Bay was ~48 Ma (early Eocene) and at Uley mine ~16 Ma (early-mid Miocene). Celadonite alteration within granulite facies metasediments of t...

Introduction A thick sequence of largely undeformed red-bed sandstones of Mesoproterozoic age, collectively termed the Pandurra Formation, overlies a wide area of crystalline basement of the central and eastern Gawler Craton. The predominantly fluvial quartz sandstones are a remnant of the continental Cariewerloo Basin deposits that extend from Whyalla in the south, northwestly for some 430 km, and up to 170 km wide, to be truncated by fault surfaces now buried beneath Mesozoic sediments of the Eromanga Basin, just to the south of Prominent Hill (Fig. 1). The full extent of the original basin is uncertain. Drill hole data indicate that the eastern margin, in particular, is disrupted by postdepositional faulting and the sandstone was extensively eroded prior to marine transgression in the Neoproterozoic, at the end of the Sturtian glaciation. The timing and duration of sedimentation is also poorly constrained with a single, whole-rock Rb-Sr isochron from interbedded shale and siltsto...

The Kanmantoo copper deposit describes a cluster of eight zones of Cu–Ag–Au mineralisation located ~2.5 km southwest of Kanmantoo township, 41 km southeast of Adelaide, South Australia. Hydrothermal chalcopyrite–pyrite–pyrrhotite–magnetite mineralisation is concentrated in structurally controlled zones within biotite, quartz, andalusite, chlorite, garnet ± staurolite schist within the western limb of the Kanmantoo syncline. Copper production began in the late 1840s with underground mining of small high-grade lodes, followed by open pit mining in 1970–76 (Verwoerd and Cleghorn 1975) and most recently in 2011 to present, with expanded open pit operations by Hillgrove Resources. Past production and current resource estimates give a
metal endowment at Kanmantoo of around 0.35 Mt of copper, 3 Moz of silver and 100 koz of gold(Rolley and Wright 2017). Estimated remaining total mineral resources, as at 31 December 2017, were 31.8 Mt at 0.6% Cu, 0.1 g/t Au, 1.3 g/t Ag, for cutoff grade 0.2% Cu (Hillgrove Resources 2018).
Continuous spectral analysis of selected drill core from various mineralised zones at Kanmantoo was completed recently by the Geological Survey of South Australia in collaboration with Hillgrove
Resources to map mineralogy and mineral associations. The results have been used to assist with interpreting proximity to mineralisation. This article provides an overview of the project and findings. The approach may be useful in assessing the potential for further mineralisation within known ore systems at Kanmantoo and offers a means of acquiring high data density for evaluating patterns of hydrothermal activity identified in exploration drill samples from other copper targets in the district.

In 2013 Australian startup, Calix Limited, built and commissioned a commercial-scale demonstrator plant at Bacchus Marsh, Victoria, based on their patented technology, to showcase a transformational calcination process for creating reactive oxide products whilst also capturing carbon dioxide (CO2) released during the reaction. Integral to
the successful commercial introduction of the technology was the quality of reactive magnesium oxide (magnesia, MgO) product achieved using cryptocrystalline magnesite (MgCO3) from the Myrtle Springs mine in South Australia. Calix has successfully marketed the product, as a magnesium hydroxide (Mg(OH)2) slurry, for pH and odor control in sewer and wastewater industries and as an effective coating for protection of sewer concrete infrastructure against acid corrosion.
New applications in aquaculture and agriculture are currently under evaluation, with field trials in Australia and overseas. Research projects are underway also into products for the health and pharmaceutical sectors, 3D printing, advanced building materials and catalysts (Calix 2018). Magnesia with a very high surface area underpins much of this activity. The relative contributions from characteristics specific to the raw magnesite feedstock and those from refinements to the kiln operating conditions to create the highly reactive MgO product are the subject of ongoing investigation. In this regard, the occurrence and
properties of marine sedimentary magnesite from the northern Flinders Ranges are somewhat unique amongst global magnesite deposits.
Of equal or greater significance for the Calix kiln technology is the effective capture of pure CO2 released during calcination. This aspect has attracted international interest, with European cement and lime producers partnering with Calix in the design and build of a  demonstration plant at HeidelbergCement’s Lixhe cement plant in Belgium. Total emissions from cement manufacture constitute ~8% of global anthropogenic CO2 emissions (Olivier et al. 2016). Over the next two years, the Calix kiln technology will be fully tested and evaluated as a key component of the LEILAC (Low Emissions Intensity Lime and Cement) project to largely eliminate CO2 process emissions from cement and lime manufacture as an important contribution towards the EU target of cutting CO2 emissions to 80% below 1990 levels by 2050
(LEILAC 2017).
The significance of the new technology for further development of South Australian magnesite resources is considered here in the context of:
• global magnesite markets and sources
• geology and characteristics of sedimentary magnesite deposits of the northern Flinders and Willouran ranges
• previous work to evaluate and develop the sedimentary magnesite resources
• history of development of the Calix kiln technology
• new market opportunities for cryptocrystalline magnesite.

During Late Miocene to Early Pliocene time (c. 7.2–5 Ma) an extensive fluvial and coastal sandplain developed across the Murray Basin in response to regional marine regression due to falling sea levels combined with gentle tectonic uplift. Sand ridges preserved across the sandplain record coastal shorelines formed at periods of highstand and stillstand during overall retreat of the sea towards the southwest. The paleocoastal beach dunes and associated shallow offshore sands have been a focus of exploration for heavy mineral (HM) deposits since discovery, in 1983, of large resources of fine-grained heavy minerals at WIM 150, near Horsham, Victoria, followed in the mid-1990s by discovery of commercial grades of coarse-grained heavy mineral sands at Wemen, Woornack and Kulwin, southeast of Mildura. In 1989, heavy mineral discoveries were made in the South Australian portion of the basin at Mindarie and Perponda. The Mindarie deposits were subsequently developed by Australian Zircon NL (2007–2009) and Murray Zircon Pty Ltd (2012–2015). Combined resources (measured, indicated and inferred), across 11 deposits reported by Murray Zircon to January 2016, totalled 244 Mt at 3.1% (total HM), with valuable heavy mineral composition averaging 17.4% zircon, 5.0% rutile, 7.4% leucoxene and 44.4% ilmenite (Murray Zircon Pty Ltd 2016). Investigation of the provenance of zircon in heavy mineral deposits in the Mindarie area was initiated to identify the relative contribution of heavy minerals from various possible source regions. The results provide data that can be used to evaluate reconstructions of the paleocoastal environment and also to assess the influence of variation in source region as a factor affecting the grade and quality of the economic heavy minerals.

A B S T R AC T : Halloysite with tubular morphology is formed in a wide range of geological environments from the alteration of various rock types. Intrusive acidic coarse-grained rocks, such as granites, pegmatites and anorthosite, with large potash and sodic feldspars contents, are subsequently altered to kaolinite, halloysite and other clay minerals by weathering or shallow hydrothermal fluid activity. Processing to separate the halloysite-kaolinite fraction from the altered host rock provides a product which can be used as a paper filler and in ceramics and fibreglass, among other uses, with various deposits in Brazil, China, Thailand and elsewhere. In the Kerikeri-Matauri Bay district of Northland, North Island, New Zealand, volcanic alkali rhyolite was extruded as domes and cooled rapidly with fine-grained feldspar subsequently altered to halloysite. The IMERYS plant in Matauri Bay separates the clay from the quartz-cristobalite matrix with an ∼20% yield of halloysite. The principal market is for high-quality porcelain and bone china that require low levels of Fe 2 O 3 and TiO 2. Deposits with high levels of halloysite occur in China, Turkey and the USA. The Dragon mine in Utah, USAwas recently reopened by Applied Minerals Inc. and now produces halloysite from zones of up to 100% white halloysite. Smaller occurrences of tubular halloysite are mined in China, Turkey and elsewhere from masses of comparatively pure clay that appear to have crystallized directly from solutions in which Al and Si were soluble.

Numerous graphite occurrences have been recorded in Neoarchean to Paleoproterozoic high-grade metamorphic rocks on Eyre Peninsula, in the southern Gawler Craton. Historic production of a few thousand tonnes is limited to the Uley graphite mine, 18 km west-southwest of Port Lincoln and Koppio graphite mine, 32 km north of Port Lincoln. A sharp increase in the price for graphite during 2010-12 led to renewed graphite exploration activity. The price rise was due to strong demand for graphite in steelmaking, a restructure of Chinese graphite mines that restricted output from the world’s leading suppliers, and anticipated increase in demand for natural flake graphite, principally for Li-ion batteries. Exploration resulted in further discoveries on Eyre Peninsula and subsequent resource drilling at Uley, Kookaburra Gully, Campoona, Wilclo South, Oakdale, and Siviour deposits. Total graphite resources across all Eyre Peninsula deposits, as at December 2016, exceeds 86Mt with grades ranging from 3 to 17% total graphitic carbon (TGC), for ~6.9Mt of in situ graphite.

Graphite is a versatile industrial mineral with unique properties that have facilitated technological innovation, beginning in the 16th century with discovery of high-grade lump graphite at Borrowdale, England.  Borrowdale graphite was carved into pencil sticks for convenient durable markers and had strategic importance as a refractory lining in moulds that produced superior, smooth and round cannonballs with greater projectile range. Today, natural graphite is a key component in high-performance refractory linings or steel manufacture, high-charge capacity anodes for lithium-ion batteries, and a source of graphene to inspire a new generation of smart materials.
Numerous graphite occurrences have been recorded in Neoarchean to Paleoproterozoic high-grade metamorphic rocks on Eyre Peninsula in the southern Gawler Craton. Total graphite resources across all Eyre Peninsula deposits, as at June 2017, exceeds 100 Mt with grades ranging from 3 to 17% TGC, for ~8.6 Mt of in situ graphite.

A B S T R A C T The supergiant Olympic Dam Cu-U-Au-Ag deposit is hosted by the Olympic Dam Breccia Complex within a ca. 1.59 Ga granite. The breccia complex is largely granite-derived but also includes volcanic clasts and domains of bedded clastic facies. Recently discovered quartz-rich sandstone has a provenance that included Paleoproterozoic and Archean units represented by zircon populations centered at ca. 2.4 Ga and ca. 1.7 Ga. The texture, detrital and cement mineralogy, and distribution of detrital zircon ages in the quartz-rich sandstone closely match those in sandstone of the Pandurra Formation deposited in the regionally extensive intracratonic Cariewerloo Basin (ca. 1.44 Ga). The age of authigenic apatite (1.44 ± 0.02 Ga) in the brecciated quartz-rich sandstone is equivalent to the minimum depositional age of the Pandurra Formation. We conclude that the quartz-rich sandstone is a remnant of the Pandurra Formation, that the Pandurra Formation originally extended across the Olympic Dam Breccia Complex, and that it was incorporated by tectonic activity at least 150 myr after initial formation of the breccia complex. Furthermore, we speculate that oxidized U-bearing fluids from the overlying Cariewerloo Basin may have interacted with the Olympic Dam U resource, consistent with mounting evidence for substantial post-1.59 Ga remobilization and probable addition of U.

The features and similarities in the geology of paleovalley-related uranium mineralizing systems in Australia and China can be used to refine strategies for exploration. Paleovalley-related uranium resources include sandstone-, lignite-and calcrete-style deposits that are developed within the host sediments deposited in paleovalleys. The paleovalleys incise either crystalline bedrock or older sedimentary rocks, and uranium was deposited and concentrated by the influx of oxidized/reduced groundwaters flowing in aquifers within the paleovalley fill. The critical features of paleovalley-related uranium deposits include sediment and uranium sources, geological setting, depositional environment, age and relative timing of mineralization, aquifer characteristics, availability and distribution of reductants, and preservation potential of the uranium mineral system. This set of information provides a basis to establish the uranium mineralization model, which can then be used to assist with generating targets for uranium exploration and prospectivity analysis of a region. With respect to Sino-Australian examples, paleovalley-related uranium deposits form mostly around the margins of sedimentary basins and the mineralization is commonly hosted within channel fills contained within paleovalleys developed upon, or proximal to, Precambrian crystalline rocks that contain primary uranium sources. The deposits that have been well studied show remarkably similar factors that controlled the formation of paleovalley-related uranium deposits. Basement/bedrocks with above-background (2.8 ppm U) levels of uranium (10–100 ppm) that are linked to, and/or, incised by paleovalleys are associated with these deposits and are the inferred source of the uranium. In these regions, extensive fluvial systems developed particularly during Mesozoic and Cenozoic times, uranium from the bedrock was first dispersed into the sediments, and then concentrated to form deposits through successive chemical remobilization, precipitation and concentration. The deposits formed in continental or marginal marine environments, and commonly are associated with reduced lithologies, containing pyrite and dispersed organic matter and/or seams of lignite, or show evidence of infiltrated hydrocarbons. The mineralization is developed where oxidizing fluids (carrying dissolved U) reacted with reductants in the sediments. Geological, geophysical and geo-chemical features of the paleovalleys and related uranium deposits are used to construct models to understand host sediment distribution, fluid flow and ore genesis that can assist exploration for paleovalley-hosted uranium deposits. Precise geometric definition of the basin margin and paleovalley architecture is important in identifying exploration targets and improving the effectiveness of drilling. Refinements in remote sensing, geophysical and data processing techniques, in combination with sedi-mentological and depositional interpretations, provide an efficient approach for outlining the principal drainage patterns and channel dimensions. To help reduce risk, an exploration strategy should combine these technologies with a detailed understanding of the physicochemical parameters controlling uranium mobilization, precipitation and preservation.

The processes leading to the formation of beach placer deposits generally begin inland and terminate at the coast, including source rocks being weathered, eroded and then transported by streams and rivers to the coast, where the sediments are deposited in a variety of coastal environments. The coastal sediments are reworked by the action of waves, tides, longshore currents and wind, which are effective processes for sorting the mineral grains based on differences in their size and density, resulting in laminated or lens-shaped packages of sediments up to tens of meters thick that are rich in heavy minerals. Detailed studies of sedimentary basins, as well as peripheral (paleo-)valleys that drained sediment source areas, are important tools in the exploration for heavy mineral resources. Knowledge of the (paleo-)basin, associated valley architecture and the source of heavy minerals concentrated in the shorelines and valleys are useful guides to the potential for, and location of, economic deposits. Evidence from sedimentology can be combined with that from other geological and geophysical characteristics to arrive at a general reconstruction of basin and paleovalley architecture and depositional environments. Complex paleogeography of the shorelines can influence or determine the sites of heavy mineral concentration. Heavy mineral sands tend to concentrate in certain shoreline settings during storm activity. Repeated storm erosion and reworking over centuries (e.g., the southeastern coast of Australia) or millennia (e.g., the Eucla and Murray Basins of Australia) can progressively enrich heavy mineral sand deposits. Preservation of these deposits over a geological timeframe of millions of years can ensue through subsidence of coastal sediments, and during sea-level change that results in either shorelines migrating inland (marine transgression) or seaward (marine regression), potentially burying or stranding earlier deposits or reworking them to form younger deposits. Refinements in remote sensing and geophysical techniques, data processing, sedimentology and computer-aided interpretations provide effective, economic and efficient methods for modeling coastal reconstructions and for exploring provinces and terrains prospective for heavy mineral sand deposits. Landscape topography analysis, combined with geophysical methods that can resolve physical property contrasts between the shoreline sediments and underlying sequences, are increasingly used in mineral exploration to locate and to reconstruct paleoshorelines and paleovalleys. Australia has modern and ancient beach-placer deposits, both of which show many similar geologic features. The formation of these heavy mineral deposits provides one of the best examples of applying knowledge of modern systems (e.g., the west and east coasts of Australia) as an analogue to interpret and understand the geology and form of ancient deposits (e.g., the Eucla and Murray Basins of southern Australia). This study provides descriptive and exploration models of Australia's heavy mineral sand deposits formed in coastal environments, which can be applied to similar settings worldwide.

The Cenozoic Eucla Basin, located on the southern margin of the Australian continent with an onshore margin extending over 2,000 km from Western Australia into South Australia, comprises a thin passive margin succession that extends from onshore to more than 500 km offshore, to the approximate foot-of-slope of the Australia’s continental margin. The basin contains a large onshore province of up to 300 m thick marine and coastal sediments of Cenozoic age, linked to an extensive network of peripheral paleovalleys that drained the Precambrian Yilgarn
Block, Gawler Craton, Musgrave Province and Officer Basin.

Understanding the geology and sedimentary evolution of the Eucla Basin and peripheral paleovalleys has relevance to the exploration for placer deposits (e.g., gold, heavy minerals), secondary geochemical deposits (e.g., uranium) and for saline and rarely potable groundwater resources in the basin and channel sediments. Knowledge of the basin and paleovalley architecture and any concentration of minerals in the channels is also of interest as guides to the location of both paleochannel and bedrock lode deposits in the surrounding cratons (e.g., Yilgarn and Gawler). Geoscientific datasets have been integrated in an investigation of this Cenozoic basin and peripheral paleovalleys that have significance for mineral exploration. The objective of the study was to understand the basin characteristics and history, and develop a comprehensive
spatial-depositional model to assist exploration in such huge basin-paleodrainage terrains. This was achieved through the combination of results from various geographical, geological and geophysical datasets. These include interpretations drawn from field observations, a compendium of geological and drilling data, computer modelling of ancient landscapes, topographic and evaluated digital elevation models, remote sensing imagery, geophysical data (e.g., magnetics, seismic,
gravity, airborne and transient electromagnetics and radiometrics, where available), all of which have contributed to a systematic investigation of both shape and depth of the basin-paleodrainage terrains. Physical property contrasts that exist between the basin/channel sediments and the underlying bedrocks, for instance, can be differentiated: by geophysical methods to locate the basin framework and paleoshorelines/paleovalleys.

Evidence from sedimentology was combined with other geological, geomorphological and geophysical characteristics to arrive at a general reconstruction of basinal and paleovalley architectures and depositional environments. The paleovalleys were incised originally into the pre-Cenozoic landscape, mostly weathered basement and Paleozoic and Mesozoic sediments, and became the sites where fluvial, lacustrine, estuarine and marine sediments accumulated during the Paleogene and
Neogene. The application of sequence stratigraphy and facies analysis across the basin and adjacent paleodrainage network were integrated to establish the changes experienced in the basin and paleovalleys as conditions, notably sea level and sediment supply, fluctuated.

This study is a review and synthesis of geoscientific research undertaken in the Eucla Basin, southern Australia during last two decades. Over that time, various investigations have been made of the geophysical and geological characteristics of the Eucla Basin and paleovalleys, and related mineralisation. These projects, particularly in the eastern basin, have assisted exploration, and provide fundamental data for increasing knowledge of geological processes and landscape evolution within this important region. This report largely reviews previous results to develop a better understanding of the characteristics, geometry, geomorphology, and geological/depositional environment of the whole basin and on mineralised sediments associated with placers and uranium deposits on the margins of the Eucla Basin.