The variability in the inherent optical properties along an estuary-coast-ocean continuum in tropical Australia has been studied. The study area, the Fitzroy Estuary and Keppel Bay system, is a shallow coastal environment (depth < 30 m) with highly turbid waters in the estuary and blue oceanic waters in the bay and subject to macrotides. Biogeochemical and inherent optical properties (IOPs) were sampled in the near-surface layer spatially and across the tidal phase during the dry season. These determinations included continuous measurements of spectral absorption, scattering and backscattering coefficients, together with discrete measurements of spectral absorption coefficients of phytoplankton, nonalgal particles and colored dissolved organic matter, and concentrations of phytoplankton pigments and suspended matter. Because of a large variability in the characteristics of the water components on short spatial and temporal scales, we observe a large variability in the associated optical properties. From the estuary to the bay, particle scattering and dissolved absorption decreased by 2 orders of magnitude, and nonalgal particle absorption decreased by 3 orders of magnitude. We also observed a strong variability in particle single scattering albedo and backscattering efficiency (by a factor of 6) and in specific IOPs (IOPs normalized by the relevant constituent concentration) such as suspended matter-specific particle scattering and chlorophyll-specific phytoplankton absorption. Superimposed on this strong spatial variability is the effect of the semidiurnal tide, which affects the spatial distribution of all measured properties. These results emphasize the need for spatially and temporally adjusted algorithms for remote sensing in complex coastal systems.

Decrepitation and degassing behaviour of quartz up to 1560 °C: Analysis of noble gases and halogens in complex fluid inclusion assemblages

Annular to crescent-shaped low back scatter SAR slicks over carbonate reefs and shoals in the Timor Sea with slick `feathering', and within the coral spawning period for the region, are interpreted to be caused by a coral spawn event. In contrast, ocean current data and detailed swath bathymetry of the sea floor to the southeast of the coral spawn slicks suggest that elongate repeating slicks in this area are related to current flow over submarine channels. Assessment of these slicks in association with ancillary data, such as bathymetry, current velocities, weather and timing of scene capture allow a more robust interpretation of their origins. Through differentiating coral spawn and bathymetric slicks from oil and other biological slicks in shallow carbonate systems, such as the Timor Sea, petroleum and environmental assessments for these areas can be improved.

Evaluation of 40Ar-39Ar quartz ages: Implications for fluid inclusion retentivity and determination of initial 40Ar/36Ar values in Proterozoic samples

The characterisation of benthic habitats based on their abiotic (physical and chemical) attributes remains poorly defined in the marine environment, but is becoming increasingly central in the development of marine management plans in Australia and elsewhere in the world. The current study tested this link between physical and biological datasets for the southern Gulf of Carpentaria, Australia. The results presented were based on a range of physical factors, including the sediment composition (grain size and carbonate content), sediment mobility, water depth and organic carbon flux, and their relationship to the distribution and diversity of benthic macrofauna was tested. The results reveal the importance of process-based indices, such as sediment mobility, in addition to other environmental factors in defining the distribution of the benthic macrofauna. The distribution of the benthic macrofauna changes gradationally across the south-eastern Gulf, associated with changes in the per cent mud and gravel, the seabed exposure and the water depth. Patterns of diversity also reveal the importance of physical processes such as sediment mobility in defining benthic habitats. The species' environment relationships observed at the small scale of the current study are consistent with broader associations observed for other organisms within the Gulf.

A seismic survey using Australian National Seismic Imaging Resource (ANSIR) Hemi60 Vibroseis vehicles, ARAM24 acquisition equipment and Pelton controllers was carried in the Curnamona province of South Australia over two periods, August 2003 and July 2004. A total of 197.6 km of 2-D data was collected to 18 seconds two way time over a single line at 60 fold CDP coverage. The project was undertaken to meet the objectives of ANSIR proposal 03-02R as lodged by researchers from Primary Industries and Resource, South Australia (PIRSA), Office of Minerals, Energy and Petroleum, SA. The principal scientific objective of this survey was to provide a regional crustal seismic image of the Curnamona Province. This dataset will assist in the understanding of the geological architecture and resource potential of the region particularly in areas under cover. This line links with a seismic transect in the Broken Hill Block undertaken by Australian Geological Survey Organisation (AGSO) in 1996 and provides a future opportunity for an eventual east-west continuation across the Adelaide Geosyncline and the Gawler Craton. The survey was funded by PIRSA, Office of Minerals, Energy and Petroleum, SA and the Predictive Minerals Discovery Cooperative Research Centre (pmd*CRC) with project supervision undertaken by ANSIR and in-kind support from Geoscience Australia (GA).

The EQRM is a computer program for modelling probabilisticseismic hazard and risk. It has formed the basis of all recent hazard and risk assessments conducted by Geoscience Australia. In this manual we describe the methodology behind the program and how to use it.

This report presents the interpretive results of a comprehensive geological framework study based on new and existing available well and seismic data. The study was initiated in 2003, as part of Geoscience Australia's Big New Oil Program to address exploration risks in a shallow water frontier basin.

This record contains the abstracts of papers presented at the pmd*CRC's 'Science at the Sharp End' conference held in Perth on 19-20 April 2006.

Small Angle Neutron Scattering (SANS), Rock-Eval pyrolysis and total organic carbon (TOC) analyses were carried out on 165 organic-rich Upper Jurassic-Lower Cretaceous sedimentary rock samples from nine wells in the Browse Basin (Adele-1, Argus-1, Brecknock South-1, Brewster-1A, Carbine-1, Crux-1, Dinichthys-1, Gorgonichthys-1 and Titanichthys-1). Cutting samples and some sidewall cores have been used. Out of the total 165 samples, 47 samples (22 for Brewster-1A and 25 for Dinichthys-1) were also analysed using the Ultra-small Angle Neutron Scattering (USANS) technique. The focus of the study was to identify potential Lower Cretaceous source rocks and the depth at which the onset of hydrocarbon generation occurred in each well, and to determine the onset of hydrocarbon expulsion in the wells for which USANS data were available.