Undiscovered hydrocarbon resources of the Bowen and Surat Basins in southern Queensland have been evaluated, on the basis of data compiled by the NGMA project Sedimentary Basins of Eastern Australia, including regional-scale seismic horizon and isopach maps and an extensive geochemical database of petroleum and potential source-rock samples. Estimates of the yields of hydrocarbons, calculated using the geochemical material balance method, are of very significant magnitude for both oil and gas. Although six principal source-rock intervals are recognised, over two-thirds of the oil is sourced from the Late Permian Baralaba interval. For gas, the Permian Buffel-Banana source unit contributes 31.5%, a significantly greater proportion than its oil counterpart, although, again, the Baralaba source unit is the most prodigious interval, yielding 40% of the total gas. A break-down of the yield in terms of major periods reveals that the Cretaceous to present-day window is by far the most important for both oil and gas generation, with 94.6% and 91.4 % of the respective totals. Thus, late structuring is more important for trap integrity than earlier structuring. By demonstrating that large quantities of hydrocarbons are potentially available for entrapment, the yield analysis should act as a stimulus to exploration initiatives, particularly in the search for stratigraphic traps.

Australia has progressed from a continent considered to have little potential for petroleum resources in 1950 to a middle-order oil and gas producer on a worldwide scale in the late 1990s. The Petroleum Search Subsidy Act (1957) encouraged exploration that resulted in discoveries in the Gippsland, Carnarvon, Amadeus, Cooper, Bowen and Surat Basins. Together with the Bonaparte and Eromanga Basins, these basins are now Australias main petroleum producing regions. Subsequently, the Petroleum (Submerged Lands) Act (1967) and various State Acts were passed to manage exploration and production. In Australia, about 7750 million barrels of crude oil and condensate (1230 gigalitres) and 96 trillion cubic feet of gas (2720 billion cubic metres) had been identified to the end of 1996. The Bureau of Resource Sciences (BRS) assessed that between 1320 million barrels (95% probability) and 3440 million barrels (5%) of crude oil remain to be discovered, and between 18 trillion cubic feet (95% probability) and 58 trillion cubic feet (5% probability) of sales gas remain to be discovered. Australias most prospective crude oil basins, ranked in order, are assessed as the Carnarvon, Bonaparte, Gippsland, Browse, Perth, Otway and Eromanga, with speculative potential in the Perth Basin, Otway Basin and other basins. The most prospective basins for sales gas are ranked as Carnarvon, Browse, Otway, Bonaparte, Cooper, Gippsland and Perth Basins. Australias likely ultimate crude oil resource was assessed as being about 52% depleted and sales gas resource as about 10% depleted at mid-1997 (BRS 1998). However, because of the relatively low level of exploration in Australia it is impossible to estimate how long the petroleum resource will last. Approximately 94% of crude oil production and 75% of gas production are from offshore. New production is likely to come mainly from already-known basins with contributions from deepwater areas and possibly the Exclusive Economic Zone.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

In its first three years, the Antarctic CRC s Natural Variability Program has focussed research effort on understanding changes in the extent of the East Antarctic ice sheet, the sedimentary processes and biogeochemical cycles affecting shelf sedimentation, and the palaeoceanography of the Southern Ocean. Seismic data from the Prydz trough-mouth fan indicate that it contains a high-resolution time series of the Plio-Pleistocene activity of the Lambert Glacier system. The fan has been prograding from the eastern side of Prydz Bay at least since the Miocene and it contains Plio-Pleistocene sediments, which are 0.8- 1.2 s TWT thick beneath the current shelf break. Radiocarbon dating of shelf sediments indicates that deposition of a Holocene siliceous mud and ooze layer was initiated at about 10 ka BP on the Mac. Robertson Shelf, which is interpreted as coinciding with the retreat of an expanded ice sheet from the shelf break. Geochemical analyses of sediment cores from the Mac. Robertson Shelf suggest significant differences in sediment accumulation between the inner and outer shelf during the Holocene. A core from the outer shelf suggests three episodes of intense diatom production separated by periods of around 1500 years, although long-term average sediment accumulation rates appear to be rather uniform for this location during the middle and late Holocene. In contrast, results for a core from the inner shelf suggest an approximately 7-fold increase in average sediment accumulation rate from the mid to late Holocene, with roughly comparable increases in the accumulation of both biogenic and lithogenic material. Palaeoceanographic studies of the Southern Ocean, using planktonic foraminifera, diatoms and alkenone unsaturation ratios, indicate larger sea surface temperature amplitudes over wider areas of the Southern Ocean during the last glacial maximum than previously suggested by CLIMAP. Our studies offer the possibility of improvements to reconstructed glacial boundary conditions, with wider areal coverage, greater reliability of estimates , and the opportunity for estimation of seasonal dynamics.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

The Mac. Robertson Shelf and western Prydz Bay, on the continental shelf of East Antarctica, were the sites of seismic/coring programs in February- March 1995 and 1997, and of an opportunistic sampling in 1993. Seismic data indicate a prograding sequence, about 200 m thick, dominated by clinoforms, in Palaeogene sediment. Core sampling was accompanied by deployment of a conductivity/temperature/depth probe (CTD), bottom camera and bottom-sediment grab. The Palaeogene sediments overlie Jurassic-Cretaceous sediments or Precambrian basement, and are overlain by thin, olive-green Quaternary diatomaceous ooze and sand. Sampling from the walls and floors of valleys crossing the shelf was on targets defined seismically, and recovered: Weakly lithified black carbonaceous or brown mudstone and siltstone with Paleocene (P4 and Paleocene undifferentiated), Middle Eocene with Globigerinatheka, and other Palaeogene foraminiferid faunas; Paleocene and Eocene pollen, spores and dinoflagellates; Sediments containing a mixture of Palaeogene fossils and Pliocene to Late Pleistocene/ Holocene diatoms and foraminifera; and Evidence of recycling from Permian, Jurassic and Cretaceous sequences. The Palaeogene sediments from the Neilsen Basin and Iceberg Alley contain glauconite and pyrite (the former often, and the latter rarely, pseudomorphic after radiolaria) and, in places, abundant carbonised wood. Radiolaria, teeth and bone fragments are rare. Foraminifera are rare and very dominantly small and calcareous with very few planktonics. The rocks appear to be part of a coastal plain sediment sequence, all weakly lithified, which includes red muddy sandstone and the fossil-bearing lithologies. It is not clear if all the fossil material and enclosing sediments are in situ or have been reworked as fragments into later glacial sediments. The faunas all appear to have accumulated in an inner continental shelf, fully marine environment with temperate-climate water temperature, and where sediment input was high compared with biogenic carbonate production. Several depositional models meet these criteria. Palynology helps define Paleocene and mid-Late Eocene depositional events, the latter marked by the Transantarctic dinocyst flora. The marine Palaeogene can be related to depositional cycles well documented from other parts of the world.

This map is part of the series that covers the whole of Australia at a scale of 1:250 000 (1cm on a map represents 2.5 km on the ground) and comprises 513 maps. This is the largest scale at which published topographic maps cover the entire continent. Each standard map covers an area of 1.5 degrees longitude by 1 degree latitude or about 150 kilometres from east to west and 110 kilometres from north to south. There are about 50 special maps in the series and these maps cover a non-standard area. Typically, where a map produced on standard sheet lines is largely ocean it is combined with its landward neighbour. These maps contain natural and constructed features including road and rail infrastructure, vegetation, hydrography, contours (interval 50m), localities and some administrative boundaries. The topographic map and data index shows coverage of the sheets. Product Specifications Coverage: The series covers the whole of Australia with 513 maps. Currency: Ranges from 1995 to 2009. 95% of maps have a reliability date of 1994 or later. Coordinates: Geographical and either AMG or MGA (post-1993) Datum: AGD66, GDA94, AHD. Projection: Universal Traverse Mercator (UTM) Medium: Paper, flat and folded copies.

The Australian Geological Survey Organisation has collected cores from two areas of the Australian continental margin- the Exmouth Plateau and Perth Basin (EP/PB) in the southeastern Indian Ocean off western Australia, and the Ceduna Terrace (CT) in the Great Australian Bight Data from seven EP/PB cores provide evidence of glacial- interglacial changes in surface ocean productivity in this region. Sediment accumulation rates and the accumulation rates of biogenic sediment components (CaCO3 and organic carbon) during the last glacial maximum (LGM, roughly 20,000 years ago) were 1.5- 2 times higher than during the Holocene. Likewise, benthic foraminiferal abundances and accumulation rates are higher in glacial sediments, as is the concentration of authigenic uranium. These data all suggest that the glacial productivity off Western Australia was elevated relative to Holocene values. Benthic foraminiferal stable isotope data from the EP/PB cores and from seven CT cores provide records of changes in intermediate and deep water chemistry in these regions since the LGM. Reconstructed LGM 13C profiles show that the deep southeastern Indian Ocean did not experience the strong glacial 13C depletion observed in the deep north Indian Ocean and in the Indian sector of the Southern Ocean.

Aluminium and iron concentrations and partitioning between particulate, colloidal and dissolved forms were examined in acid run-off from known acid sulphate soil environments in the lower Richmond River catchment during dry season conditions. Chronically acid drains in the Tuckean Swamp and Rocky Mouth Creek exhibited extremely high concentrations of dissolved metals (8- 10 mg/L Al , 5mg/L Fe). Dissolved aluminium and iron were quickly transformed to solid hydroxide species, which were rapidly removed from the water column by the aggregation and precipitation of diaspore and hematite in distinct flocculation zones, as water was subjected to steep pH and salinity gradients. This suggests that high metal concentrations may be found in benthic sediments and biota. Dissolved metals in acid runoff represent a major source of environmental pollution and, combined with the effects of acidity and low dissolved oxygen levels, pose a significant threat to estuarine ecosystems.

Seagrasses are specialised flowering plants with roots and vascular tissue. They differ from algae in that they can absorb and translocate nutrients from soft sediments. This provides seagrasses with access to the generally higher nutrient pools in sediments compared with the overlying water column. The interactions between seagrasses and the sediments surrounding their roots are important in nutrient cycling. Microbial flora in the seagrass rhizosphere form an intimate association with the seagrasses. In particular, nitrogen-fixing bacteria have a very close associationwith seagrass roots. Nitrogen fixed in the sediments can be found in seagrass leaves within hours, although seagrasses do not appear to have endosymbiotic associations like many terrestrial plants. Seagrasses influence the bacteria surrounding the roots via exudation of dissolved organic carbon and oxygen and through seagrass nutrient uptake. This association between seagrasses and bacteria affects both the rates and pool sizes of various elements in the sediments.