At this scale 1cm on the map represents 1km on the ground. Each map covers a minimum area of 0.5 degrees longitude by 0.5 degrees latitude or about 54 kilometres by 54 kilometres. The contour interval is 20 metres. Many maps are supplemented by hill shading. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours, localities and some administrative boundaries. Product Specifications Coverage: Australia is covered by more than 3000 x 1:100 000 scale maps, of which 1600 have been published as printed maps. Unpublished maps are available as compilations. Currency: Ranges from 1961 to 2009. Average 1997. Coordinates: Geographical and either AMG or MGA coordinates. Datum: AGD66, GDA94; AHD Projection: Universal Transverse Mercator UTM. Medium: Printed maps: Paper, flat and folded copies. Compilations: Paper or film, flat copies only.

Collation of talks and posters completed under the APCRC Program 5 during June 1999-June 2001.

Organic geochemists are increasingly involved in multi-disciplinary collaborative studies but not often in the initial sample collection phase, so understanding the origin and source of contaminants derived from sample handling and containers is of vital importance as standard laboratory blanks cannot assess this contamination. A variety of organic contaminants was detected in different sediments collected during Geoscience Australia marine survey S282. These include fatty acid amides, chemical antioxidants such as butylated hydroxytoluene and octadecyl-3, 5-di-tert-butyl-4-hydroxyhydrocinnamate (Irganox 1076), plus the UV absorbers octabenzone and octyl methoxycinnamate. These compounds were introduced during sampling on board the research vessel or during subsequent handling. Solvent extraction of potential contamination sources identified two brands of plastic sampling bags as the main source for the fatty acid amides, butylated hydroxytoluene and Irganox 1076. Direct contact of samples with hands covered with sunscreen appears to have caused contamination by octabenzone and octyl methoxycinnamate. As the primary aim of the survey was to detect evidence for hydrocarbon seepage in the Arafura Sea, care was also taken to identify potential sources of hydrocarbons that might have been introduced during sampling and storage. Detailed examination of solvent extracts from plastic bags revealed the occurrence of several homologous series of branched alkanes with quaternary carbon atoms (BAQCs), as well as distributions of alkyl cyclohexanes and alkyl cyclopentanes with strong even over odd carbon predominance. These compounds were also found in sediment samples collected during the survey. Other potential sources of contamination used on board the ship, such as PVC core liners and lubricants, yielded hydrocarbons that could easily be mistaken for evidence of naturally occurring petroleum if care is not taken during interpretation.

Presentation delivered on 9 March 2012 by Marita Bradshaw.

The 50 major Australian source rock units can be grouped according to age into 15 intervals comprising Late Neoproterozoic, Middle Early Ordovician, late Early Ordovician, Middle to Late Devonian, Early Carboniferous, Early to early Late Permian, late Late Permian, Early to Middle Triassic, Early to Middle Jurassic, Middle to Late Jurassic, Late Jurassic, latest Jurassic to Early Cretaceous, Early Cretaceous, Late Cretaceous, latest Cretaceous to Eocene. Only marine source rocks are known older than Permian, while both marine and nonmarine source rocks are known from Permian and younger intervals. As expected, the marine source rocks are more common where there is a greater degree of continental inundation, while nonmarine source rocks are present only when the continent was at higher palaeolatitudes and when there was at least a moderate amount of continental inundation.

Subsidence and thermal history analysis of 24 wells and seismic-defined depocentre sites has been undertaken to investigate the generation and expulsion history of the Early Carboniferous and Permian petroleum systems in the Petrel Sub-basin. Modelled oil and gas expulsion from postulated oil-prone source units within the Lower Carboniferous Milligans Formation is restricted to two offshore depocentres immediately north and south of the Turtle-Barnett High. Expulsion commenced in the Late Carboniferous, reached its peak in the Early Permian, and minor expulsion continued throughout the Permian and Early-Mid Triassic prior to the onset of regional uplift associated with the Late Triassic Fitzroy Movement. Limited gas expulsion is also modelled in the onshore Carlton Sub-basin, and although this unit is sufficiently mature in this area to have generated oil, the models suggest that generated volumes are insufficient for expulsion of oil. Modelled oil and gas expulsion from mudstones and coaly mudstones of the Lower Permian Keyling Formation is restricted to the central and outer portions of the Petrel Deep. Expulsion from the outer Petrel Deep occurred in the Late Permian - Early Triassic, and expulsion from the central Petrel Deep commenced and peaked in the Early Triassic, with subsequent phases of minor expulsion in the Late Triassic - Cretaceous. Oil expelled from these source units may have migrated to pre-Fitzroy Movement structures and stratigraphic traps within and on the flanks of the Petrel Deep, but to date the only possible indication of such an oil charge are low confidence SAR slick anomalies east and southeast of the Petrel Field. Modelled gas expulsion from the Upper Permian Hyland Bay Formation is limited to the outboard limits of the Petrel Sub-basin, and occurred in the Jurassic-Cretaceous with peak expulsion in the mid-late Cretaceous. This unit is considered too lean to expel significant quantities of oil. These expulsion models are integrated with the known distribution of hydrocarbon accumulations, shows and SAR anomalies to map the extent of the petroleum systems in the Petrel Sub-basin. These maps can then be used to assess the likely source(s) of the recent Blacktip-1 gas discovery, and to evaluate the charge potential of traps within the sub-basin, including those within the 2002 offshore acreage release areas.

This CD contains a collection of reports on samples from Arafura Basin wells (biostratigraphy, organic petrology, fluid inclusions - GOI, organic geochemistry and geohistory modelling) generated by GA staff and by external contractors and collaborators based on new analyses carried out during 2004 and 2005.

AGSO's 1995-96 Petrel Sub-basin Study was undertaken within AGSO's Marine, Petroleum and Sedimentary Resources Division (MPSR) as part of MPSR's North West Shelf Project. The study was aimed at understanding the stratigraphic and structural development of the basin as a framework for more effective and efficient resource exploration. Specifically, the study aimed to: - define the nature of the major basement elements underlying the Petrel Sub-basin and their influence on the development of the basin through time, - determine the nature and age of the events that have controlled the initiation, distribution and tectonic evolution of the basin; - define the nature and age of the basin fill, and the processes that have controlled its deposition and deformation; and, importantly, - determine the factors controlling the development and distribution of the basin's petroleum systems and occurrences.

Abundant, micron-scale, spherical aggregates of 2?5 nm diameter sphalerite (ZnS) particles formed within natural biofilms dominated by relatively aerotolerant sulfate-reducing bacteria of the family Desulfobacteriaceae. The biofilm zinc concentration is about 106 times that of associated groundwater (0.09 ? 1.1 ppm Zn). Sphalerite also concentrates arsenic (0.01 wt %) and selenium (0.004 wt %). The almost monomineralic product results from buffering of sulfide concentrations at low values by sphalerite precipitation. These results show how microbes control metal concentrations in groundwater and wetland-based remediation systems and suggest biological routes for formation of some low temperature ZnS deposits.

No abstract available