Pockmarks have been observed around the world's ocean and lake beds for decades. They indicate shallow and/or deep sub-surface fluid seepage, and may occur in isolation or in groups. Dense fields of pockmarks were identified in three areas (510 km2) mapped using multibeam sonar in the Oceanic Shoals Commonwealth Marine Reserve, located in the tropical Timor Sea on the Australian continental shelf. The pockmarks occur in flat, barren, silty plains (~105 m water depth) which surround extensive carbonate banks and terraces (~40-75 m water depth). The banks hosted rich communities of benthic organisms including sponge gardens and corals. A distinctive feature of many of the pockmarks in this area is a linear scour mark that extends up to 200 m from pockmark depressions. Previous numerical and flume tank simulations have shown that scouring of pockmarks occurs in the direction of the dominant near-seabed flow. These geomorphic features may therefore serve as a proxy for local-scale bottom currents, which may in turn provide information on sediment processes influencing biodiversity patterns in the region. In this presentation, we: 1) provide information on the methods used to characterise and count the scoured and non-scoured depressions (i.e. an automated method involving ArcGIS spatial analyst tools); (2) draw on other datasets to provide information on why the pockmarks developed (e.g. multibeam backscatter and geochemical variables); and 3) investigate their potential as an environmental proxy (oceanographic) for benthic habitat studies.

A comprehensive assessment of the performance of predictive models is needed as they have been increasingly employed to generate spatial predictions for environmental management. This study clarified the definition of variance explained (VECV) for predictive models and revealed the relationships between commonly used predictive accuracy measures and VECV that is independent of unit/scale and data variation and unifies these measures. We quantified the relationships between these measures and data variation, further assessed the accuracy of predictive methods in environmental sciences and classified the predictive models based on VECV. This study provides a tool to directly compare the accuracy of predictive models for data with different unit/scale and variation, and establishes a cross-disciplinary context and benchmark for assessing predictive models in environmental sciences and other disciplines.

Although marine reserves are becoming increasingly important as anthropogenic impacts on the marine environment continue to increase, we have little baseline information for most marine environments. In this study, we focus on the Oceanic Shoals Commonwealth Marine Reserve (CMR) in northern Australia, particularly the carbonate banks and terraces of the Sahul Shelf and Van Diemen Rise which have been designated a Key Ecological Feature (KEF). We use a species-level inventory compiled from three marine surveys to the CMR to address several questions relevant to marine management: 1) Are carbonate banks and other raised geomorphic features associated with biodiversity hotspots? 2) Are there environmental or biogeographic variables that can help explain local and regional differences in community structure? 3) How do sponge communities differ between individual raised geomorphic features? Approximately 750 sponge specimens were collected in the Oceanic Shoals CMR and assigned to 348 species, of which only 18% included taxonomically described species. Between the eastern and western CMR, there was no difference between sponge species richness or assemblages on raised geomorphic features. Within individual raised geomorphic features, sponge assemblages were significantly different (ANOSIM: Global R = 0.328, p < 0.001), but species richness was not. There were no environmental factors related to sponge species richness, although sponge assemblages were weakly but significantly related to several environmental variables (mean depth, mean backscatter, mean slope). These patterns of sponge diversity are considered in the context of marine reserve management in order to explore how such information may help support the future management of this region.

Poster describing the Hydrogeological Atlas of the Great Artesian Basin. The atlas is structured into three sections. Section one (maps 1 to 22) presents important hydrogeological and geological aspects of the GAB, including the regional hydrostratigraphy, the outcrop and subcrop extents of the major aquifers and aquitards, the position of major faults and structural features and groundwater pressure and flow directions in the main artesian aquifer. Section two (maps 23 to 32) provides details on the extent and thickness of the major aquifers and aquitards that constitute the GAB. Section 3 (maps 33 to 55) shows the spatial variation in groundwater chemistry found within the major aquifers of the GAB.

The Vlaming Sub-basin is an elongated, north-south trending Mesozoic depocentre in the Perth Basin, Western Australia containing up to 14 km of sediments. A number of potential plays at different stratigraphic levels were identified by the previous exploration. Although potential plays were described for the Early Cretaceous Gage Sandstone overlain by the South Perth Shale seal, they were not successfully explored in any detail. The exploration primarily focused on structural traps in the syn-rift succession due to the assumption that all hydrocarbons were generated prior to or at the time of the breakup. Petroleum systems modelling undertaken in 2007 concluded that some source rocks in the sub-basin reached maturity after the deposition of the South Perth Shale seal, therefore making plays in the post-breakup Gage reservoir prospective. Deposited as a lowstand component of the deltaic South Perth Supersequence, the Gage Lowstand Fan (previously referred to as the Gage Sandstone) infilled paleotopographic lows of the Valanginian breakup unconformity. Characteristics of the reservoir-seal pair were derived from sequence-stratigraphic analysis and seismic facies mapping by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the South Perth Supersequence reveal a series of regressions and transgressions that infill the paleodepressions. The Gage reservoir is a sand-rich submarine fan system and ranges from canyon-confined inner fan deposits to middle fan deposits on a basin plain. Sand sheets in the distal middle fan and stacked channelized sands in the inner fan may provide an extensive reservoir of good to excellent quality. Characteristics of the South Perth Shale seal vary greatly across the basin and may account for some dry wells. A re-evaluation of the regional seal determined the extent of the pro-delta shale facies within the South Perth Supersequence, which provides an effective seal for the underlying Gage reservoir. 3D geological modelling provided a better understanding of the reservoir heterogeneity. Flow path analysis identified multiple stratigraphic closures at the top of the Gage reservoir, with the most favourable located in the Rottnest Trough.

The Stavely Project is a collaboration between Geoscience Australia and the Geological Survey of Victoria. During 2014, fourteen pre-competitive stratigraphic drill holes were completed in the prospective Stavely region in western Victoria in order to better understand subsurface geology and its potential for a variety of mineral systems. Prior to drilling, existing airborne magnetic data were analysed and new refraction seismic, reflection seismic and gravity data were acquired as part of a pre-drilling geophysical acquisition program. The aim of this geophysical program was to provide cover thickness estimates at the drill-site locations prior to the drilling program commencing, in order to reduce the geological and financial risk. Passive seismic data were acquired post-drilling for benchmarking with the other methods against the completed drilling in order to assess a potential tool kit of geophysical methods for the explorer to predict reliably the cover thickness at the tenement scale.

The Browse Basin located offshore on Australia's North West Shelf hosts considerable, but as yet undeveloped, petroleum resources with 36 Tcf EUR (Estimated Ultimate Recovery) of gas and 1148 MMbbl of condensate. It is poised to become Australia's next major conventional liquefied natural gas (LNG) province with the Ichthys, Prelude and Concerto fields expected to be in production by the end of 2016. Significant gas accumulations are also found along, and to the northeast of, the Brecknock-Scott Reef Trend (Calliance, Brecknock, Torosa and Poseidon) and in the Heywood Graben (Crux). Despite the economic importance of these fields and the extensive ongoing exploration activity, the origin of hydrocarbons remains ambiguous and a thorough geochemical evaluation of reservoir fluids and source rocks was carried out to redefine the petroleum systems of the Browse Basin. Geochemical data reveal that the gas-prone source rocks occurring throughout the Lower to Middle Jurassic Plover Formation have pervasively charged reservoirs of the Browse Basin at numerous stratigraphic levels. On the other hand, oil-prone source rocks within the Upper Jurassic lower Vulcan and Lower Cretaceous Echuca Shoals formations appear to be charge limited. The fluvio-deltaic sediments of the Plover Formation are the primary source for the dry gas found in the Plover reservoirs of the Brecknock-Scott Reef Trend and Ichthys fields. The Plover source rocks have also contributed to the wet gas accumulations reservoired within the Upper Jurassic Brewster Member of the Ichthys and Prelude/Concerto fields with additional inputs from the lower Vulcan Formation. Gases from the Crux field in the Heywood Graben are isotopically more enriched in 13C than any gases generated from the Caswell Sub-basin depocentre suggesting derivation from coal-rich facies within thick Jurassic syn-rift sediments. The few sub-economic oil discoveries made in the Browse Basin are confined to the central Caswell Sub-basin (Caswell) and to the Yampi Shelf (Cornea, Gwydion and surrounds) where oil, together with some gas, is found in Cretaceous reservoirs. Molecular and carbon isotopic data show that the oil, and the gas to some extent, is derived from marine organic matter within the Echuca Shoals Formation. However, accumulations on the Yampi Shelf also contain gases sourced from Plover source rocks, emphasising the migration of multiple hydrocarbon charges towards the basin margins.

The formation and preservation of many types of ore-deposits has been temporally linked to the assembly and breakup of supercontinents. The late Paleoproterozoic to early Mesoproterozoic is a time of major metallogenesis in Australia and elsewhere, and may be linked to the assembly and break-up of the Nuna/Columbia Supercontinent. This study presents geochemical and isotopic data from Paleo- to early Mesoproterozoic sedimentary successions in northern Australia that complement existing regional stratigraphic correlations, and thereby, reduce exploration risk. A significant proportion of global orogenic gold mineralization occurred in the time interval 2100 1800 Ma. This corresponds with a time during which oceans are thought to have been relatively iron-rich, and the sedimentary record is characterized by a major period of deposition of iron-rich sedimentary rocks, including banded iron formations. In northern Australia, orogenic gold deposits in the Tanami and Pine Creek provinces are hosted by anomalously iron-rich marine mudstones deposited between ~1910 and 1800 Ma. The ~1810 Ma Callie deposit in the Tanami Province, the largest gold deposit in northern Australia, is hosted by black, iron-rich mudstones of the Dead Bullock Formation, which contains ~275 t of gold. Black mudstones of the Koolpin Formation in the Pine Creek province have produced ~99 t of gold, including 17 t at the Cosmo Howley Deposit. Effective exploration in the Tanami and Pine Creek provinces is severely hampered due to poor knowledge of potential stratigraphic correlations within and between regions. However, gold-bearing units in both provinces are characterized by high Cr/Th, low Th/Sc, and low (La/Yb)PAAS, which together suggest that these rocks had a dominant mafic source. These characteristics can be used to identify stratigraphic units most favourable to host gold mineralization. After 1800 Ma, and after the first global oxygenation event, the metallogeny of northern Australia changed significantly, possibly in response to geodynamic changes and the oxidation of the atmosphere and hydrosphere. Metallogenesis in the period between 1655 Ma and 1575 Ma is characterized by oxidised fluid flow that produced zinc-lead deposits upon interaction with anoxic mudstones. During this time most of the zinc-lead deposits that constitute the North Australian Zinc Belt formed. Late paleoproterozoic sedimentary basins across the Northern Australian Zinc Belt record a significant change in their neodymium isotopic composition to more positive epsilon Nd values at ~1655 Ma. This isotopic change is interpreted to reflect increased mafic magmatism accompanying initial break-up of Nuna, and is recognized in the Mt Isa, Georgetown and Curnamona provinces and the Victoria River Basin, which, together host the North Australian Zinc Belt. This change, which may reflect a buried or eroded eastern Proterozoic Australian source or an outboard Laurentian source, can be used to identify portions of the Paleoproterozoic stratigraphy with higher potential to host zinc-lead deposits.

Geoscience Australia (GA), as custodian of the geographical and geological data and knowledge of the nation, has recently implemented a new data discovery and delivery system for offshore wells and surveys the National Offshore Petroleum Information Management system (NOPIMS). In order to encourage adoption and use of the NOPIMS by industry, this five page article for PESA News describes the origins of the NOPIMS, its current state and future development plans.

Terrain illumination correction is an important step in the normalisation of remotely sensed data for the inversion of land surface parameters, and for applications that aim to detect land surface change through time series analysis. To accurately normalise for the terrain effect, an appropriate resolution of the Digital Elevation Model (DEM) data with sufficient quality is critical for effective correction of remotely sensed data over mountainous areas. Conversely, using terrain illumination correction and scale-based analysis, such as filter bank analysis, the quality of DEM data can be evaluated. In this study, TanDEM-X Intermediate DEM (IDEM) data at 12 m and 30 m resolutions, and the 1-second SRTM data (~ 30 m resolution) were used to evaluate their effectiveness for terrain illumination correction of Landsat satellite data. The island of Tasmania in Australia has a fine scale of terrain detail as well as high relief. The high latitude and strong variability in the terrain illumination throughout the year make it an ideal study site for applying the methods available for this evaluation. Results from the terrain illumination correction and filter bank analysis show that IDEM 12 m and 30 m resolution datasets can resolve finer details of terrain shading than the SRTM based DEMs and deliver better results in the areas with detail-rich terrain. However, since the data available for this study is an intermediate product, spikes and other noise artefacts were prevalent, especially over areas covered by water. Operational use of the IDEM would require the removal of such noise artefacts. The filter bank analysis also found that both Landsat panchromatic data and IDEM 12 m data are oversampled and the signal-to-noise parameters for both DEM and Landsat data are yet to be fully established. Further evaluation of the relative merits of the TanDEM-X based DEM data and the SRTM based DEM data for terrain illumination correction would be possible when the WorldDEM product based on TanDEM-X data becomes routinely available.