This dataset provides the spatially continuous data of the seabed sand content (sediment fraction 63-2000 mm) expressed as a weight percentage ranging from 0 to 100%, presented in 0.01 decimal degree resolution raster format. The dataset covers the Australian continental EEZ, including seabed surrounding Tasmania. It does not include areas surrounding Macquarie Island, and the Australian Territories of Norfolk Island, Christmas Island, and Cocos (Keeling) Islands or Australia's marine jurisdiction off of the Territory of Heard and McDonald Islands and the Australian Antarctic Territory. This dataset supersedes previous predictions of sediment sand content for the Australian Margin with demonstrated improvements in accuracy. Accuracy of predictions varies based on density of underlying data and level of seabed complexity. Artefacts occur in this dataset as a result of insufficient samples in relevant regions. This dataset is intended for use at national and regional scales. The dataset may not be appropriate for use at local scales in areas where sample density is insufficient to detect local variation in sediment properties. To obtain the most accurate interpretation of sediment distribution in these areas, it is recommended that additional samples be collected and interpolations updated.

Recent centuries provide no precedent for the 2004 Indian Ocean tsunami, either on the coasts it devastated or within its source area. The tsunami claimed nearly all of its victims on shores that had gone 200 years or more without a tsunami disaster. The associated earthquake of magnitude 9.2 defied a Sumatra-Andaman catalogue that contains no nineteenth-century or twentieth-century earthquake larger than magnitude 7.9. The tsunami and the earthquake together resulted from a fault rupture 1,500 km long that expended centuries -worth of plate convergence. Here, using sedimentary evidence for tsunamis, we identify probable precedents for the 2004 tsunami at a grassy beach-ridge plain 125 km north of Phuket. The 2004 tsunami, running 2 km across this plain, coated the ridges and intervening swales with a sheet of sand commonly 5-20 cm thick. The peaty soils of two marshy swales preserve the remains of several earlier sand sheets less than 2,800 years old. If responsible for the youngest of these pre-2004 sand sheets, the most recent full-size predecessor to the 2004 tsunami occurred about 550-700 years ago.

There is growing global concern for the impact of increased fluvial sediment loads on tropical coral reefs and seagrass ecosystems. The Fitzroy River is a macrotidal, tide-dominated estuary in the dry tropics of central Queensland and is a major contributor of sediment to the southern Great Barrier Reef (GBR) lagoon. The estuary currently receives most of its sediment during large episodic flood events commonly associated with cyclonic depressions. The sediment dynamics of macrotidal estuaries and especially of wet-dry tropical systems, with intermittent flows and sediment discharge are poorly understood. Average annual sediment budgets for such a system are also difficult to estimate due to the sporadic nature of flood discharge events. Therefore we have estimated a long-term sediment accumulation rate of catchment-derived sediment trapped in the estuary using the Holocene stratigraphic sequence, determined from a series of sediment cores, dated with radiocarbon and optically stimulated luminescence (OSL), and integrated with industry borehole data. We estimate that 17,400 million tonnes (Mt) of river sediment has accumulated in the estuary during the last 8000 years. This suggests a minimum mean annual bulk sediment discharge of the Fitzroy River of 2000 kt yr-1. This estimated 2175 kilotonnes per year (kt yr-1) of bulk sediment is equivalent to 25% of the estimated average annual modern bulk sediment discharge of the Fitzroy River of 8800 kt yr-1, (Kelly and Wong, 1996) suggesting that the sediment trapping efficiency of the Fitzroy estuary during the Holocene has been approximately 25%. This implies that 75% of the river sediment has been exported from the estuary into Keppel Bay and the adjacent GBR lagoon during the Holocene. With minimal accommodation space left in the floodplain, modern sediment accumulation appears to be focussed around the mangroves and tidal creeks, which cover an area of 130 km2. Cores from the tidal creeks were dated using 137Cs, excess 210Pb, and OSL and display sedimentation rates of approximately 1.5 cm yr-1 for the last 45-120 years, or 1700 kt yr-1, and suggest a modern sediment trapping efficiency for the estuary of around 19%. These results provide useful insights into the long-term sedimentation and quantification of the sediment trapping efficiency of a subtropical macro-tidal estuary with episodic floods, where sediment trapping will vary seasonally and inter-annually.

This report provides a description of the activities completed during the Outer Darwin Harbour Mapping Survey, from 28 May and 23 June 2015 on the RV Solander (Survey GA0351/SOL6187). This survey was a collaboration between Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and Department of Land Resource Management (Northern Territory Government) and the first of four surveys in the Darwin Harbour Seabed Habitat Mapping Program. This 4 year program (2014-2018) aims to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline information and developing thematic habitat maps that will underpin future marine resource management decisions. The program was made possible through funds provided by the INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The specific objectives of the Outer Darwin Harbour Marine Survey GA0351/SOL6187 were to: 1. Obtain high resolution geophysical (bathymetry) data for outer Darwin Harbour, including Shoal Bay; 2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for outer Darwin Harbour, including Shoal Bay; and 3. Collect tidal data for the survey area. Data acquired during the survey included: 720 km2 multibeam sonar bathymetry and acoustic backscatter; 96 sampling stations collecting seabed sediments, underwater photography and video imagery and oceanographic information including tidal data and 54 sound velocity profiles.

This dataset provides the spatially continuous data of seabed mud content (sediment fraction < 63 µm) expressed as a weight percentage ranging from 0 to 100%, presented in 0.01 decimal degree resolution raster format. The dataset covers the Australian continental EEZ, including seabed surrounding Tasmania. It does not include areas surrounding Macquarie Island, and the Australian Territories of Norfolk Island, Christmas Island, and Cocos (Keeling) Islands or Australia's marine jurisdiction off of the Territory of Heard and McDonald Islands and the Australian Antarctic Territory. This dataset supersedes previous predictions of sediment mud content for the Australian Margin with demonstrated improvements in accuracy. Accuracy of predictions varies based on density of underlying data and level of seabed complexity. Artefacts occur in this dataset as a result of insufficient samples in relevant regions. This dataset is intended for use at national and regional scales. The dataset may not be appropriate for use at local scales in areas where sample density is insufficient to detect local variation in sediment properties. To obtain the most accurate interpretation of sediment distribution in these areas, it is recommended that additional samples be collected and interpolations updated.

Geoscience Australia carried out marine surveys in Jervis Bay (NSW) in 2007, 2008 and 2009 (GA303, GA305, GA309, GA312) to map seabed bathymetry and characterise benthic environments through co-located sampling of surface sediments (for textural and biogeochemical analysis) and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wave-generated currents. Data and samples were acquired using the Defence Science and Technology Organisation (DSTO) Research Vessel Kimbla. Bathymetric mapping, sampling and tide/wave measurement were concentrated in a 3x5 km survey grid (named Darling Road Grid, DRG) within the southern part of the Jervis Bay, incorporating the bay entrance. Additional sampling and stills photography plus bathymetric mapping along transits was undertaken at representative habitat types outside the DRG. Seabed sediment samples were collected by a Shipek grab at a total of 126 locations. (see Anderson et al. 2009). Sediment grabs typically recovered a sample up to 5 cm by 12 cm in area and 5 cm thick, from which a 50 - 100 g sub-sample was taken to a depth of ~2 cm. Sub-samples were stored in plastic bags and refrigerated.

The National Geochemical Survey of Australia: The Geochemical Atlas of Australia was published in July 2011. Released along with this publication was a digital copy of the geochemical dataset that included basic particle size data. This dataset includes extended particle size data for NGSA samples.

This resource contains surface sediment data for Bynoe Harbour collected by Geoscience Australia (GA), the Australian Institute of Marine Science (AIMS) and Department of Land Resource Management (Northern Territory Government) during the period from 2-29 May 2016 on the RV Solander (survey SOL6432/GA4452). This project was made possible through offset funds provided by INPEX-led Ichthys LNG Project to Northern Territory Government Department of Land Resource Management, and co-investment from Geoscience Australia and Australian Institute of Marine Science. The intent of this four year (2014-2018) program is to improve knowledge of the marine environments in the Darwin and Bynoe Harbour regions by collating and collecting baseline data that enable the creation of thematic habitat maps that underpin marine resource management decisions. The specific objectives of the survey were to: 1. Obtain high resolution geophysical (bathymetry) data for outer Darwin Harbour, including Shoal Bay; 2. Characterise substrates (acoustic backscatter properties, grainsize, sediment chemistry) for outer Darwin Harbour, including Shoal Bay; and 3. Collect tidal data for the survey area. Data acquired during the survey included: multibeam sonar bathymetry and acoustic backscatter; physical samples of seabed sediments, underwater photography and video of grab sample locations and oceanographic information including tidal data and sound velocity profiles. This dataset comprises grain size data measured on seabed sediments. A detailed account of the survey is provided in Siwabessy, P.J.W., Smit, N., Atkinson, I., Dando, N., Harries, S., Howard, F.J.F., Li, J., Nicholas W.A., Picard, K., Radke, L.C., Tran, M., Williams, D. and Whiteway, T., 2016. Bynoe Harbour Marine Survey 2017: GA4452/SOL6432 - Post-survey report. Record 2017/04. Geoscience Australia, Canberra. Thanks to the crew of the RV Solander for help with sample collection, Matt Carey, Craig Wintle and Andrew Hislop from the Observatories and Science Support at Geoscience Australia for technical support and Jodie Smith for reviewing the data. This dataset is published with the permission of the CEO, Geoscience Australia

Recently discovered drift deposits on the Antarctic continental shelf provide access to information on the Holocene palaeoceanography of the bottom current regime within deep shelf basins that were previously inaccessible. The George Vth Basin on the East Antarctic margin has been identified by oceanographers as an important source of Antarctic Bottom Water, hence the Holocene history of bottom current activity here may be relevant to variations in bottom water export.

This report is one of a series of environmental summaries of frontier basins, which are scheduled for acreage release during the timeframe of the 'Energy Security Initiative' (2007-2011). The aim of these reports is to synthesise the available environmental information to adequately equip the exploration industry to anticipate as many as possible of the environment-related issues that may impact on exploration and potential future production activities. The environmental information for the Vlaming Sub-basin and Mentelle Basin has been compiled and presented in a manner consistent with the Geographic Information System (GIS) provided with this report. The GIS includes the results of an analysis to obtain representative seascapes. Seascapes are the principal environmental output and in recent years assisted Department of Environment, Water, Heritage and the Arts with the design and implementation of a National Representative System of Marine Protected Areas for Australia (Section 1.1). The following section summarises the geological history of the Vlaming Sub-basin and Mentelle Basin and provides a tectonic and depositional context for the geophysical data and geomorphology of the sub-basin, which are discussed in Sections 3 and 4, respectively. The surface sediment properties are described in Section 5. These sections provide all of the information necessary to characterise benthic habitats. Section 6 discusses the oceanographic processes operating in the sub-basin, which influence both the benthic and pelagic ecology described in Section 7. Section 8 synthesises the information contained in the first seven sections into a seascape map of the Vlaming Sub-basin and Mentelle Basin.