This study used angular response curves of multibeam backscatter data to predict the distributions of seven seabed cover types in an acoustically-complex area. Several feature analysis approaches on the angular response curves were examined. A Probability Neural Network model was chosen for the predictive mapping. The prediction results have demonstrated the value of angular response curves for seabed mapping with a Kappa coefficient of 0.59. Importantly, this study demonstrated the potential of various feature analysis approaches to improve the seabed mapping. For example, the approach to derive meaningful statistical parameters from the curves achieved significant feature reduction and some performance gain (e.g., Kappa = 0.62). The first derivative analysis approach achieved the best overall statistical performance (e.g., Kappa = 0.84); while the approach to remove the global slope produced the best overall prediction map (Kappa = 0.74). We thus recommend these three feature analysis approaches, along with the original angular response curves, for future similar studies.

Disturbances characterise many natural environments - on land, a forest fire that removes a patch of old-growth trees is an example. The trees that first colonise the vacant patch may be a different species to the surrounding old-growth forest and hence, taken together, the disturbed and undisturbed forest has a higher biodiversity than the original undisturbed forest. This simple example demonstrates the intermediate disturbance hypothesis (IDH) that has applications in many natural environments. The application of IDH is significant for managers tasked with managing and conserving the biodiversity that exists in a given area. In this report we have used models of seabed sediment mobilisation to examine IDH for Australia's continental shelf environment. Although other disturbance processes may occur (eg. biological, temperature, salinity, anthropogenic, etc.) our study addresses only the physical disturbance of the seabed by waves and currents. Our study has shown that it is feasible to model the frequency and magnitude of seabed disturbance in relation to the dominant energy source (wave-dominated shelf, tide-dominated shelf or tropical cyclone dominated shelf). We focussed our attention on high-energy, patch-clearing events defined as exceeding the Shields parameter value of 0.25. Based on what is known about rates of ecological succession for different substrate types (gravel, sand, mud) we derive maps predicting the spatial distribution of a dimensionless ecological disturbance index (ED). Only a small portion of the shelf (perhaps ~10%) is characterised by a disturbance regime as defined here. Within these areas, the recurrence interval of disturbance events is comparable to the rate of ecological succession and meets our defined criteria for a disturbance regime. To our knowledge, this is the first time such an analysis has been attempted for any continental shelf on the earth.

This glossary gives a brief description of the more important sedimentary rocks. Composition percentages are tentative in nearly all cases. The terms listed are classified as follows.

Seismic reflection data show the existence of two major sedimentary basins along the continental margin of Wilkes Land and Terre Adélie, East Antarctica, that contain more than 5 s TWT (> 9 km) of sediments. Four seismic megasequences are identified (MS4 to MS1) that are bounded by: basement, unconformities of interpreted Turonian, Maastrichtian and early Middle Eocene age, and the seafloor. The 4-5 km thick rift and pre-rift sediments are concentrated in a margin-parallel basin (Sabrina Basin). On the basis of seismic correlation with the Australian margin, this basin is interpreted to be of Late Jurassic to mid-Cretaceous age. The post-rift sediments are generally thick along the margin and in the adjacent deep-ocean basin, but are particularly thick in a major depocentre off west Wilkes Land, named here the Budd Coast Basin (BCB). The BCB contains a maximum observed thickness of 5 s TWT (9 km) of post-rift sediments and its location suggests that the sediments were largely derived from a sub-glacial basin currently occupied by the Totten Glacier.

No abstract available

Cool-water carbonate environments may be responsible for up to one third of the carbonate sediment produced on continental shelves, and are useful modern analogues for many geologically ancient deposits. The extensive southern margin of the Australian continent is recognised as the world's largest modern example of a high energy, cool-water carbonate depositional realm. A number of studies have suggested that Quaternary sediment production here is largely influenced by oceanography, and that wave abrasion strongly limits sediment accumulation. Therefore, in this region the outer-shelf, below the storm wave base, is thought to be the focus of sediment accumulation. The inner shelf is considered a zone of active sediment production due to the proliferation of carbonate secreting organisms, although few studies have investigated sediment production or accumulation in this energetic and dynamic environment. The Recherche Archipelago, which sits at the western margin of the Great Australian Bight (GAB), was examined to better understand Quaternary shelf evolution and the importance of this type of inner shelf as a carbonate 'factory'. Surficial sediments, video, multibeam sonar data, cores and shallow seismics were collected. The present seabed of the archipelago features extensive areas where flat-lying limestones sit over the often irregular granite basement. The Pleistocene erosional surface is overlain by a coarse bivalve and rhodolith dominated gravel lag. Significantly, there are extensive Holocene deposits, up to 7 m thick, throughout the archipelago, particularly in association with granite islands. These deposits comprise cross-bedded gravelly carbonate sands dominated by fragments of calcareous algae (rhodoliths), molluscs and bryozoans. In contrast, the inshore and coast is dominated by terrigenous sediment. Seismic profiles and preserved palaeo-shoreline features suggest that slow but episodic aggradation of marine sediment has occurred on the inner shelf over successive Quaternary sea level cycles, although there are also extensive areas of non-deposition. This accumulation is partly attributable to the sheltering effect of high-relief granitic outcrops and cementation of subaerially exposed carbonate sediments.

These preliminary notes deal with the sequence as it is found in the Giralia Structure. The analysis of the Cretaceous-Tertiary megafauna is described. The findings of the investigation with respect to the sedimentary sequence are discussed.

Geoscience Australia undertook a marine survey of the Vlaming Sub-basin in March and April 2012 to provide seabed and shallow geological information to support an assessment of the CO2 storage potential of this sedimentary basin. The survey was undertaken under the Australian Government's National CO2 Infrastructure Plan (NCIP) to help identify sites suitable for the long term storage of CO2 within reasonable distances of major sources of CO2 emissions. The Vlaming Sub-basin is located offshore from Perth, Western Australia, and was previously identified by the Carbon Storage Taskforce (2009) as potentially suitable for CO2 storage. The principal aim of the Vlaming Sub-basin marine survey (GA survey number GA0334) was to look for evidence of fault reactivation and of any past or current gas or fluid seepage at the seabed. The survey also mapped seabed habitats and biota in the areas of interest to provide information on communities and biophysical features that may be associated with seepage. This data package brings together the following datasets which describe biophysical aspects of seafloor sediments: GEOCAT#74276. Underwater video footage from the Vlaming Sub-basin (GA0334). GEOCAT#76463. GA0334 Vlaming sub-basin Species identification of worms from grab. GEOCAT#78540. Vlaming Sub-Basin Marine Environmental Survey (GA-0334/S. Supporter GP 1373) (NCIP Program) - High Resolution Bathymetry grids. GEOCAT# 78550. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Chlorin analyses of seabed sediments. GEOCAT#78551. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Inorganic elements of seabed sediments. GEOCAT#78552. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Bulk organic carbon and nitrogen isotopes and concentrations in seabed sediments. GEOCAT#78553. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Sediment oxygen demand of seabed sediments. GEOCAT#78564. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Chlorophyll a, b and c of seabed sediments. GEOCAT#78565. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: %carbonate and specific surface area of seabed sediments. GEOCAT#79176. Seabed environments and shallow geology of the Vlaming sub-basin, Western Australia: Grain size and carbonate concentrations of seabed sediments. GEOCAT#79345. Ecology / Infaunal morphospecies identifications from the Vlaming Sub-basin (GA0334). An account of the field operations is published in: GEOCAT 74626. Nicholas, W. A., Borissova, I., Radke, L., Tran, M., Bernardel, G., Jorgensen, D M., Siwabessy, J., Carroll, A. and Whiteway, T., 2012. Seabed Environments and Shallow Geology of the Vlaming Sub-Basin, Western Australia - Marine data for the Investigation of the Geological Storage of CO2. GA0334 Post-Survey Report. Geoscience Australia, Record 2013/09. A preliminary interpretation of seabed data is provided in: GEOCAT 78846. Nicholas, W. A., Howard, F., Carroll, A., Siwabessy, J., Tran, M., Picard, K., Przeslawski, R. and Radke, L. 2014. Seabed Environments and shallow sub-surface geology of the Vlaming Sub-basin, offshore Perth Basin: summary report on observed and potential seepage, and habitats. Geoscience Australia, Record 2014/XXX. Information on the broader study, evaluating the Vlaming Sub-basin CO2 storage potential and providing details of the suitable storage sites, is available in: GEOCAT 79332. Borissova, I, Lech, M.E., Jorgensen, D.C, Southby, C., Wang, L., Bernardel, G., Nicholas, T., Lescinsky, D.L. and Johnston, S. An integrated study of the CO2 storage potential in the offshore Vlaming Sub-basin. Geoscience Australia, Record 2014/XXX.

The Petrel Sub-basin Marine Survey GA-0335 (SOL5463) was undertaken on RV Solander during May 2012 as part of the Commonwealth Government's National Low Emission Coal Initiative (NLECI). The survey was a collaboration between the Australian Institute of Marine Science (AIMS) and GA. The purpose was to acquire geophysical and biophysical data on shallow (less than 100 m water depth) seabed environments within two targeted areas in the Petrel Sub-basin to support the investigation of CO2 storage potential in these areas. Unconsolidated surface (seabed) sediments were collected at 11 sampling stations using a Smith_McIntyre grab (10L volume). Sediment samples were collected to provide data on a) sedimentology, b) infauna and c) the geochemical composition of the sediments. For the sedimentology (this dataset) up to 250 g of sediment was sub-sampled from the surface (0-2 cm) of the sediment recovered in the Smith_McIntyre grabs. Sub-samples were described from visual inspection, noting grain size, sorting and composition and these were stored in plastic bags and refrigerated. These were subsequently analysed at the GA laboratories to provide information on the texture and composition of the sediments at the sampling locations. Grain size measurement was undertaken by wet sieving to determine mud (<63 microns), sand (63-2000 microns) and gravel (>2000 microns) fractions as percentage of dry weight. A separate sub-sample (~1g) was used for laser diffraction measurement of the mud and sand fractions using a Malvern Mastersizer 2000, with results expressed as percentage of the total particle volume based on an average of three measurements on each sample. Particle size distributions including mean, median, and standard deviation, together with skewness and kurtosis indices were calculated. Separate sample splits were taken for measurement of the carbonate content using the carbonate bomb method following Muller and Gastner (1979).

Increased loads of land-based pollutants associated with land use change are a major threat to coastal-marine ecosystems globally. Identifying the affected areas and the scale of influence on marine ecosystems is critical to assess the ecological impacts of degraded water quality and to inform planning for catchment management and marine conservation. Studies using remotely-sensed data have contributed to our understanding of the occurrence and extent of influence of river plumes, as well as to assess exposure of ecosystems to river-borne pollutants. However, refinement of plume modelling techniques is required to improve risk assessments. We developed a novel approach to model exposure of coastal-marine ecosystems to river-borne pollutants. The model is based on supervised classification of true-colour satellite imagery to map the extent of plumes and to qualitatively assess the dispersal of pollutants in plumes. We use the Great Barrier Reef (GBR) to test our approach. We combined frequency of plume occurrence with spatially-distributed loads (based on a cost-distance function) to create maps of exposure to suspended sediment and dissolved inorganic nitrogen. We then compared annual exposure maps (2007-2011) to assess inter-annual variability in the exposure of coral reefs and seagrass beds. Our findings indicate that classification of true colour satellite images is useful to map plumes and to qualitatively assess exposure to river-borne pollutants. This approach should be considered complementary to remote sensing methods based on ocean colour products used to characterise surface water in plumes. The proposed exposure model is useful to study the spatial and temporal variation in exposure of coastal-marine ecosystems to riverine plumes. Observed inter-annual variation in exposure of habitats to pollutants stresses the need to incorporate the temporal component in exposure and risk models.