Nara Inlet in the Whitsunday Islands is a natural depocenter for clastic and carbonate sediment on the middle shelf of the central Great Barrier Reef (GBR) platform. Three sediment cores were collected from the inlet to understand sediment accumulation in this tropical mixed clastic/carbonate system over time. Surface and subsurface sediment is comprised of two main components: terrigenous clay and shallow marine carbonate. Similar to other regions on the middle shelf of the GBR platform, the carbonate component, 25.80% by weight and dominated by Sr-poor foraminifera tests and mollusc shells, generally increases towards the surface. Radiocarbon ages derived from tests of benthic foraminifera indicate that the top 3 m of sediment accumulated within the last 3000 years, but that the rate has slowed toward present-day. The change in clastic and carbonate abundance therefore indicates a system where both clastic and carbonate accumulation has decreased over time, but where clastic accumulation has decreased faster. Reduced clastic accumulation may reflect progressive impedance of terrigenous input by a laterally growing fringing reef at the mouth of Nara Inlet. Likewise, reduced carbonate accumulation may reflect preferential reef growth and carbonate deposition outside of the inlet. Even though clastic accumulation has decreased significantly over time, the late Holocene mass, composition, and distribution of clastic material in Nara Inlet implies a terrigenous source previously unrecognized in models for the evolution of the GBR platform. Large amounts of terrigenous sediment probably were stored around topographic highs on the middle shelf during lowstand and early transgression. This clastic material was then removed over time, mixed with autochthonous carbonate, and deposited in embayments on the middle shelf. The accumulation of sediment on the middle shelf of a tropical mixed clastic/carbonate margin is not straightforward.

Palaeomagnetic, rockmagnetic and magnetic fabric results are presented for a Carboniferous (Visean to Westphalian) succession of felsic, mainly ignimbritic, volcanic and volcaniclastic rocks from the Rocky Creek Block of the northern Tamworth Belt, southern New England Orogen. Detailed thermal demagnetization of 734 samples from 64 sites has shown three groups of magnetic components with low (LT: up to 300 degrees C), intermediate (IT: 300 to 600 degrees C) and high (HT: mainly 500 to 680 degrees C) unblocking temperature ranges. Analysis and interpretation of component directions have established well-defined primary magnetization results fro 29 sites and evidence for four magnetic overprint phases.The overprints are of widespread (a,c) or localized (b,d) occurrence and are attributed to: a mid_tertiary weathering event (a: mainly LT); or to fluid movements (b,c,d) associated with either Late Cretaceous opening of the Tasman Sea (b: mainly HT); or to thrusting during the Middle Triassic main phase of the Hunter_Bowen Orogeny (c: mainly IT); or to latest Carboniferous - Early Permian formation of the Bowen-Gunnedah-Sydney Basin system (d: IT,HT). Rockmagnetic (Lowrie-Fuller test, IRM acquisition, Lowrie-test, low- and high-temperature susceptibility cycling) and palaeomagnetic analyses indicate predominance of magnetite carriers with main unblocking temperatures ranging from 400 to between 500 and 580 degrees C, and less prevalent presence of hematite carriers with unblocking temperature ranges generally up to 640 degrees C and for some sites up to 680 degrees C. Multidomain (MD-) magnetite is prevalent in the volcaniclastic rocks. Most of the volcanic rocks with well-defined primary magnetization components show evidence for single domain (SD-) magnetite with no, or only limited, presence of MD-magnetite. See paper for remainder of abstract

We propose a geodynamic model for the generation of Fe oxide Cu-Au deposits in the eastern Gawler Craton. Rifting during the early Calymnian Period, at 1.59 Ga, produced steep geothermal gradients, active magmatism, regional-scale faulting, and immature clastic sedimentation. Major NNW?SSE-trending, dextral transtensional faults exerted fundamental structural controls on several elements of the mineral system: the geometry of intrusion of magmas of the Hiltaba Suite; the provision of fluid pathways for magnetite- and haematite-buffered fluids; creation of basinal space for the effusive lavas of the Gawler Range Volcanics and the overlying terrigeneous sediments of the Pandurra Group; and propagation of near-surface fault tips giving rise to fault-bound hydrothermal breccias. We demonstrate that faults active at 1.59 Ga were of sufficient dimension and seismic longevity to have acted as fluid pumps within the mineral system. Their size and location imply multiple sources for metals in the Olympic Dam deposit and other Fe oxide Cu-Au occurrences in the region. Multiple sources would have resulted in some of the anomalous features of the mineralisation, such as non-magmatic Br:Cl ratios, and magmatic and juvenile, mafic isotopic signatures, all noted by previous workers. Isostatic footwall uplift in the actively extending system may have compressed the regional geothermal gradients, and brought rock volumes altered by hot, reduced fluids into contact with circulating cooler, oxidised fluids. In general, fluid circulation and deposition was enhanced by deformation-induced permeabilities and hydrofracture. In the time-span of the mineral system, say 3 million years, mineralisation cycles (source-transport-deposition) may have repeated 102 to 106 times, depending on the hydraulic conductivity of the source rocks. Some associations at the Olympic Dam deposit, such as granite and maar-like volcanism, are fortuitous and are not essential elements of the mineral system. In the light of the geodynamic model, geophysical. geochemical, and petrological data may be examined for evidence of likely source rocks, fluid pathways, and suitably oxidised magnetite deposits that may contain ore.

In ecology, a common form of statistical analysis relates a biological variable to variables that delineate the physical environment, typically by fitting a regression model or one of its extensions. Unfortunately, the biological data and the physical data are frequently obtained from separate data sources. In such cases there is no guarantee that the biological and physical data are co-located and the regression model cannot be used. A common and pragmatic solution is to spatially predict the physical variables at the locations of the biological variables and then use the predictions as if they were observations. In this article, we show that this procedure can cause potentially misleading ferences when fitting a generalised linear model as an example. We propose a Berkson-error model which overcomes the limitations. The differences between using predicted covariates and the Berkson error model are illustrated using data from the marine environment, and a simulation study based on this data.

Steep terrain affects optical satellite images through both irradiance and BRDF effects. To obtain corrected land surface reflectance and detect land surface change through time series analysis over rugged surfaces, it is necessary to remove or reduce the topographic effects. In this paper, a physical based BRDF and atmospheric correction model for both flat and sloping surfaces in conjunction with the 1-second SRTM (Shuttle Radar Topographic Mission) derived DSM product was applied to conduct BRDF, atmospheric and terrain correction. The model was applied to 8 Landsat scenes covering different seasons and terrain types in eastern Australia. Initial visual assessment showed that the algorithm removed much of the topographic effect and detected deep shadows in all 8 images. Indirect validation based on the change in correlation between the data and terrain slope showed that the correlation coefficient between the surface reflectance factor and the cosine of the incident (sun) angle reduced dramatically after the topographic correction algorithm was applied. The correlation coefficient typically reduced from 0.80 to 0.02 in areas of significant relief. The terrain corrected surface reflectance can also provide suitable input data for multi-temporal land cover classification in areas of high relief based on spectral signatures and spectral albedo, while the products based only on BRDF and atmospheric correction cannot. To ensure stability of the terrain corrected reflectance products when expert intervention in the processing workflow needs to be minimal, the paper also shows the need for additional constraints and calibration the correction algorithm. For example, to avoid overcorrection, the algorithm currently applies an angle threshold to both the BRDF model and the direct irradiance. Above all, the accuracy and effectiveness of the product is shown to depend particularly on the quality of the DSM data, its co-registration with the Landsat data and its spatial resolution.

The Tarcoola Goldfield is one of several districts included in the recently proposed central Gawler gold province. Understanding of the genesis of the deposits in this metallogenic province is in its infancy, and dating the age of alteration, mineralisation and microdiorite dyke intrusions has been carried out at Tarcoola as a first step towards developing mineral-systems models for the province. At Tarcoola, four samples of sericite from alteration as well as one sample of hornblende from a microdiorite dyke yield 40Ar/39Ar ages of ca 1580 Ma. Geological and petrological relationships suggest that this age represents the time of fracture-controlled Au mineralisation. These data provide evidence for coeval Au mineralisation, microdiorite dyke intrusion and local deformation. This mineralisation age is indistinguishable from U-Pb ages for the regional Gawler Range - Hiltaba volcano-plutonic complex, and is more than 100 million years younger than the Paxton Granite, which is part-host to the mineralisation. Possible temporal and genetic relationships with other deposits in the central Gawler gold province remain to be tested.

The carbon isotopic composition is measured for three species of planktonic foraminifera (Globigerina bulloides, Globorotalia inflata and Neogloboquadrina pachyderma (s.)) from Southern Ocean sediment traps. The sediment traps represent the annual flux of foraminifera in Subtropical to Polar Frontal environments from the western Pacific/Southern Australia sector. Comparison between the seasonal d13C composition of the foraminifera and estimated d13C of dissolved inorganic carbon (DIC) allows disequilibrium effects to be determined. Disequilibrium exhibits a latitudinal trend, with greatest offsets from equilibrium at lower latitudes. This effect causes a north to south increase in foraminiferal d13C, while the d13CDIC displays a decrease across these latitudes. Disequilibrium in G. bulloides can be accounted for by changes in temperature. The relationship between disequilibrium and temperature which we derive in this field study is consistent with the laboratory relationship of Bemis et al. [2000] . Corrected d13C for G. bulloides is closely correlated to seasonal changes in nutrients at each site, indicating the utility of G. bulloides d13C as a nutrient tracer in Southern Ocean environments. Comparison between flux-weighted sediment trap values and nearby core tops indicates a modern depletion in d13C, which we attribute to the oceanic Suess effect. The imprint of this effect on the foraminiferal isotopes provides further evidence for the equilibration between surface waters and the atmosphere in the Subantarctic Zone.

Australia's nickel sulfide industry has had a fluctuating history since the discovery in 1966 of massive sulfides at Kambalda in the Eastern Goldfields of Western Australia. Periods of buoyant nickel prices and high demand, speculative exploration, and frenetic investment (the 'nickel boom' years) have been interspersed by protracted periods of relatively depressed metal prices, exploration inactivity, and low discovery rates. Despite this unpredictable evolution, the industry has had a significant impact on the world nickel scene with Australia having a global resource of nickel metal from sulfide ores of not, vert, similar 12.9 Mt, five world-class deposits (> 1 Mt contained Ni), and a production status of number three after Russia and Canada. More than 90% of the nation's known global resources of nickel metal from sulfide sources were discovered during the relative short period of 1966 to 1973. Australia's nickel sulfide deposits are associated with ultramafic and/or mafic igneous rocks in three major geotectonic settings: (1) Archean komatiites emplaced in rift zones of granite-greenstone belts; (2) Precambrian tholeiitic mafic-ultramafic intrusions emplaced in rift zones of Archean cratons and Proterozoic orogens; and (3) hydrothermal-remobilized deposits of various ages and settings. The komatiitic association is economically by far the most important, accounting for more than 95% of the nation's identified nickel sulfide resources. The ages of Australian komatiitic- and tholeiitic-hosted deposits generally correlate with three major global-scale nickel-metallogenic events at not, vert, similar 3000 Ma, not, vert, similar 2700 Ma, and not, vert, similar 1900 Ma. These events are interpreted to correspond to periods of juvenile crustal growth and the development of large volumes of primitive komatiitic and tholeiitic magmas caused by large-scale mantle overturn and mantle plume activities. There is considerable potential for the further discovery of komatiite-hosted deposits in Archean granite-greenstone terranes including both large, and smaller high-grade (5 to 9% Ni) deposits, that may be enriched in PGEs (2 to 5 g/t), especially where the host ultramafic sequences are poorly exposed. Analysis of the major komatiite provinces of the world reveals that fertile komatiitic sequences are generally of late Archean (not, vert, similar 2700 Ma) or Paleoproterozoic (not, vert, similar 1900 Ma) age, have dominantly Al-undepleted (Al2O3/TiO2 = 15 to 25) chemical affinities, and often occur with sulfur-bearing country rocks in dynamic high-magma-flux environments, such as compound sheet flows with internal pathways facies (Kambalda-type) or dunitic compound sheet flow facies (Mt Keith-type). Most Precambrian provinces in Australia, particularly the Proterozoic orogenic belts, contain an abundance of sulfur-saturated tholeiitic mafic ± ultramafic intrusions that have not been fully investigated for their potential to host basal Ni-Cu sulfides (Voisey's Bay-type mineralization). The major exploration challenges for finding these deposits are to determine the pre-deformational geometries and younging directions of the intrusions, and to locate structural depressions in the basal contacts and feeder conduits under cover. Stratabound PGE-Ni-Cu ± Cr deposits hosted by large Archean-Proterozoic layered mafic-ultramafic intrusions (Munni Munni, Panton) of tholeiitic affinity have comparable global nickel resources to many komatiite deposits, but low-grades (< 0.2% Ni). There are also hydrothermal nickel sulfide deposits, including the unusual Avebury deposit in western Tasmania, and some potential for 'Noril'sk-type' Ni-Cu-PGE deposits associated with major flood basaltic provinces in western and northern Australia.

We report the discovery of three submerged, living patch coral reefs covering 80 km2 in the southern Gulf of Carpentaria, Australia, an area previously thought not to contain coral bioherms. The patch reefs have their upper surfaces at a mean water depth of 28.6±0.5 m, and were consequently not detected by satellites or aerial photographs. The reefs were only recognised in our survey using multibeam swath sonar supplemented with seabed sampling and under water video. Their existence points to an earlier, late Quaternary phase of framework reef growth, probably under cooler climate and lower sea level conditions than today. Submerged reefs with surfaces between 20 and 30 m water depth occur in other regions of the Earth and existing bathymetry indicates they could be widespread in the Gulf. Many tropical regions that today do not support patch or barrier reefs for reasons similar to the modern Gulf, may have done so in the past, when environmental conditions were more suitable. Submerged reefs may provide an important refuge for corals during the next few decades when near-surface reefs are threatened by widespread coral bleaching due to warmer global sea surface temperatures.

The Perth Basin is localised by reactivation of Neoproterozoic shear zones on the western margin of the Archaean Yilgarn Craton in Western Australia. While Ordovician to Silurian sandstones were deposited in the northern Perth Basin, the earliest sediments elsewhere are Middle Carboniferous to Permian in age. A sinistral transtensional regime, during which the main architecture of the basin was established, developed during NE-SW extension between Greater India and Western Australia in the Permo-Triassic. NW-SE shortening with continued NE-SW extension resulted in sinistral transpression in the late-Early to Middle Triassic. Sag-phase sedimentation in the LateTriassic followed this oblique rifting event. An analogy may be made between the Perth Basin and the Permo-Carboniferous to Jurassic Karoo basins in southern and central Africa and Madagascar. Deposition of the Karoo sequence took place within pull-apart and transtensional basins resulting from sinistral reactivation of basement shear zones. The Indian Gondwana Supergroup, and an equivalent sequence in Antarctica, were deposited within normal fault-bounded graben. The Late Paleozoic to Early Mesozoic formation of the Perth Basin, the Karoo basins of Africa and Madagascar, and the Gondwana basins of India was due to intraplate stress resulting from convergence along the Panthalassa margin of Gondwanaland. Late-Early to Middle Triassic compressional events in all basins mark terminal collision along the Panthalassa margin.