The Recherche Archipelago lies within the westernmost reaches of the Great Australian Bight, a large cool-water carbonate depositional province on the southern Australian margin. The inner shelf of the archipelago comprises numerous islands, typically comprising Proterozoic granites, which protrude from the shelf of mainly recent carbonate sediments. The area is influenced by extreme Southern Ocean swell energy, which results in a typically wave-abraded inner shelf, and sediment deposition mainly on the mid- to outer shelf. For Esperance Bay, a large shallow-water embayment within the archipelago, we examined the relationships between bottom sediments, geomorphology and the distribution of biotic habitats by integrating multibeam sonar, underwater video and sediment grab sample information. Major benthic habitats, such as seagrass beds, rhodolith beds, rocky reefs and mobile sand sheets are characterised in terms of their sea bed morphology, sedimentology and bioclastic composition. The littoral zone comprises mature quartz sand dominated by seagrasses, whereas the mainly carbonate-dominated shelf sediments are typically coarse gravely sands, and contain significant quantities of granitic material that is accumulating in areas of low wave exposure, typically behind the rocky islands. Bioclasts are dominated by red algal, bryozoan and foraminiferal components, as well as relict material. Sediment lags and calcarenite reefs occur in areas of high wave exposure, often with significant covers of macro-algae and sponges. The abundance of sediment producing organisms such as shallow-water rhodoliths and the presence of large-scale mobile sediment bedforms suggests that due to the influence of the rocky islands, the localised production and accumulation of carbonate sediments in the Recherche Archipelago is significantly greater than that observed in other parts of the Great Australian Bight inner shelf.

Positioned at the transition zone of the major hydrocarbon provinces of Browse and Bonaparte Basins, Ashmore Reef is built on what is thought to be Pleistocene antecedent topography. This mature, ovoid, shelf-edge reef experiences the seasonal oceanic influences of Indian Ocean and of the Indonesian-Through-Flow. The model for its development is derived from the post glacial (past 11,000 years) relative sea level curve, C14 dated facies changes and the reef growth phases extrapolated from the One Tree Reef model (Marshall & Davis 1982). A thorough visual examination of the reef was augmented with a series of 12 vibro-cores through algal-foraminiferal sand and coral, across the bioturbated platform. Changes in the lagoonal sediment facies were carbon dated giving dates ranging from 970 to 2020 (~70 years) BP. They indicated a major bio-facies change from robust vertical coral columns to an algal dominated reef crest and reef flats as sea level stabilised at ~2000 BP. Ashhmore Reef is presently characterised by high biodiversity and extensive coral growth, broad reef flats littered with coral boulders, and three vegetated cays. An extensive series of highly mobile and heavily bioturbated biogenic sand sheets adjoin two lagoons. Both are within a pronounced ovoid, algal-cemented, reef rim. The sediments comprised principally of Halimeda sp., coral fragments, foraminifera, molluscs and a range of coralline algae that infill the lagoon at up to 0.73 cm/yr. The three vegetated cays are capped with guano and all have wash-over deposits of pumice, wood, shell and coral.

The production of icebergs from Antarctic ice shelves represents fluctuations in the mass of the icesheet. Mapping the age, distribution and size of iceberg scour marks on the seafloor provides insight into the dynamics of the icesheet and circulation patterns through time. Sidescan sonar records from the Prydz Bay continental shelf are used to determine the relative ages of scour marks on this shelf as modern, relict and very relict, and their width, length and orientation. Modern scour marks on this shelf are shown to occur at average depths of 285 m, up to a maximum of 400 m. This range is broadly consistent with modern keel depths (248-352 m) for icebergs produced from the Amery Ice Shelf. Relict scours occur at average depths of 486 ± 78 m, while very relict scours occur at average depths of 650 ± 60 m. No iceberg scours are observed at depths greater than 750 m. The depth range of relict scours is consistent with iceberg scouring during periods of lower glacial sea level, combined with the production of icebergs with larger keel depths during major deglaciations. The very deep setting of the oldest scours implies the production of icebergs from a very thick iceshelf, possibly relating to major retreat of the icesheet towards the grounding line during periods of extreme glacial retreat.

These data were derived from the Australian Bathymetry database held at Geoscience Australia. The dataset comprises depth, seabed morphometric parameters: slope, aspect, topographic relief and rocky layer, and geomorphic features.

Ashmore Reef is an ovoid, shelf edge, platform reef located on the north west shelf of Australia (~ 12? 20? S, 123? 00? E) at the north-western boundary of the Browse and Bonaparte basins. Built on antecedent topography, it is the largest emergent reef with the highest biodiversity in the region. Geomorphological expressions of the carbonate platform include three vegetated cays with a sub-surface fresh water lens, guano deposits and beach rock, two lagoons separated by an calcareous algal rise, large scale mobile inter-tidal and sub-tidal sand flats, extensive lineated reef flats up to 1.7 km wide, an algal dominated reef rim rise, and a precipitous reef front with classical spur and groove morphology. Sedimentological analysis shows that the modern sand accumulations are primarily foraminifera, coral, molluscan fragments and a range of coralline algae (mainly Halimeda sp). The reef is subject to a 4.75 m semi-diurnal tide and lagoonal water temperatures range between 25.2 and 35.4?C. The climate is tropical monsoonal, and warm to hot, with the annual mean temperature at 28.5?C. Regional data indicate that rainfall exceeds 950 mm, and evaporation potential is 1820 mm. Dominant SW trade winds drive the surface currents and these interplay with the Indian Ocean and are seasonally influenced by southward moving Indonesian-Though-Flow waters. Thunderstorms occur on ~ 85 days in the wet season and the region experiences 7% of the global annual total of cyclones.

Legacy product - no abstract available

This data product contains seabed morphology and geomorphology information for a subset area of Zeehan Marine Park. A nationally consistent seabed geomorphology classification scheme was used to map and classify the distribution of key seabed features. The Zeehan Marine Park seabed morphology and geomorphology maps were derived from a 2 m horizontal resolution bathymetry DEM compiled from a multibeam survey undertaken for Parks Australia by the University of Tasmania. Semi-automated GIS mapping tools (GA-SaMMT); (Huang et. al., 2022; eCat Record 146832) were applied to a bathymetry digital elevation model (DEM) in a GIS environment (ESRI ArcGIS Pro) to map polygon extents (topographic high, low, and planar) and to quantitatively characterise polygon geometries. Geometric attributes were then used to classify each shape into discrete Morphology Feature types (Dove et. al., 2020; eCat Record 144305). Seabed geomorphology features were interpreted by applying additional datasets and domain knowledge to inform their geomorphic characterisation (Nanson et. al., 2023; eCat Record 147818). Where available, backscatter intensity, seabed imagery, and survey reports supplemented the bathymetry DEM and morphology classifications to inform the geomorphic interpretations. The data product and classification schema are fully described in the accompanying Data Product Specification. Dove, D., Nanson, R., Bjarnadóttir, L. R., Guinan, J., Gafeira, J., Post, A., Dolan, Margaret F.J., Stewart, H., Arosio, R., Scott, G. (2020). A two-part seabed geomorphology classification scheme (v.2); Part 1: morphology features glossary. Zenodo. https://doi.org/10.5281/zenodo.4075248; Huang, Z., Nanson, R., Nichol, S. 2022. Geoscience Australia's Semi-automated Morphological Mapping Tools (GA-SaMMT) for Seabed Characterisation. Geoscience Australia, Canberra. https://dx.doi.org/10.26186/146832 Nanson, R., Arosio, R., Gafeira, J., McNeil, M., Dove, D., Bjarnadóttir, L., Dolan, M., Guinan, J., Post, A., Webb, J., Nichol, S. (2023). A two-part seabed geomorphology classification scheme; Part 2: Geomorphology classification framework and glossary (Version 1.0) (1.0). Zenodo. https://doi.org/10.5281/zenodo.7804019

Christmas Island is an Australian territory lying south of Java inthe Indian Ocean, at about 10°30'S and 105°40'E. It lies on oceanic crust of Late Cretaceous age, is moving north at 7cm/year, andis being raised as it climbs the bulge on the southern flank of the Java Trench. The island itself consists of Cainozoic volcanics and limestone, and has been extensively mined for Pliocene phosphate. It covers an area of 140 km2 , and rises 360 m above sea level. Australia has declared a 200 mile Fisheries Zone around the island, and the aim of this BMR investigation is to assess the seabed morphology, sediment thickness, and offshore mineral resources in a future Exclusive Economic Zone. This information will be of particular value to the Department of Foreign Affairs and Trade, when Australia negotiates a Christmas Island seabed boundary with Indonesia to the north. Present knowledge indicates that oceanic crust is generally at 5000-6000 m around Christmas Island, and that it is overlain by 100-300m of pelagic sediment which thickens northward toward the Java Trench. A number of volcanic ridges trend generally northeast or north-northeast, and are as shallow as 1200 m below sea level. Christmas Island itself sits on such a ridge. Shallow-water limestones and manganese oxide crusts have been dredged from the ridges. Deepseacoring programs show that pelagic foraminiferal ooze and marl give way to siliceous (diatom-radiolarian) ooze and red clay below 5000 in water depth. Volcanic ash from Indonesia is an additional component of the sediment. Reconnaissance sampling has shown that manganese nodules are quite common in the deep sea, and that they carry moderate grades of the valuable metals, copper (Cu), nickel (Ni) and cobalt (Co). In a fairly similar geological setting to the west, in the central Indian Ocean, India has pioneer investor status for a nodule mine site of 150,000 square kilometres. At this site the grade of Cu+Ni+Co is about 2.55%,and nodule abundance is 5-7.5% of wet nodules per square metre, figures which suggest that the site has long-term economic potential. The present project will commence with a 28-day geoscience cruise of R.V. "Rig Seismic" from 7 January to 4 February, 1992. The plan isto acquire about 2500 km of high-resolution reflection seismic and bathymetric data, to define seabed morphology and to allow regional mapping of sediment thickness and facies. The seismic data will beused as the basis of a sampling campaign to investigate sediment type, manganese nodule abundance and metal grade on the deepsea floor, and manganese crust thickness and metal grade on the volcanic ridges. The end result will be a comprehensive review of the geology and mineral resources of the Christmas Island offshore zone.

<div>This data product contains geospatial seabed morphology and geomorphology information for the Beagle Marine Park and is intended for use by marine park managers, regulators, the general public and other stakeholders. A nationally consistent two-part (two-step) seabed geomorphology classification system was used to map and classify the distribution of key seabed features. </div><div><br></div><div>In step 1, semi-automated GIS mapping tools (GA-SaMMT; Huang et al., 2022; eCat Record 146832) were applied to bathymetry digital elevation models (DEM) in a GIS environment (ESRI ArcGIS Pro) to map polygon extents (topographic high, low, and planar) and quantitatively characterise their geometries. The geometric attributes were then used to classify each shape into discrete Morphology Feature types (Part 1: Dove et al., 2020; eCat Record 144305). In step 2, the seabed geomorphology was interpreted by applying additional datasets and domain knowledge to inform their geomorphic characterisation (Part 2: Nanson et al., 2023; eCat Record 147818). Where available, backscatter intensity, seabed imagery, seabed sediment samples and sub-bottom profiles supplemented the bathymetry DEM and morphology classifications to inform the geomorphic interpretations.</div><div><br></div><div>The Beagle Marine Park seabed morphology and geomorphology features were informed by a post survey report (Barrett et al., 2021). Seabed units were classified at multiple resolutions that were informed by the underlying bathymetry: </div><div><br></div><div>· A broad scale layer represents features that were derived from a 30 m horizontal resolution compilation DEM (Beaman et al 2022; eCat Record 147043). </div><div>· A series of medium and fine scale feature layers were derived from individual 1 m horizontal resolution DEMs (Nichol et al., 2019; eCat Record 130301). </div><div><br></div><div>The data product and application schema are fully described in the accompanying Data Product Specification. </div><div><br></div><div><em>Barrett, N, Monk, J., Nichol, S., Falster, G., Carroll, A., Siwabessy, J., Deane, A., Nanson, R., Picard, K., Dando, N., Hulls, J., and Evans, H. (2021). Beagle Marine Park Post Survey Report: South-east Marine Parks Network. Report to the National Environmental Science Program, Marine Biodiversity Hub. University of Tasmania.</em></div><div><br></div><div><em>Beaman, R.J. (2022). High-resolution depth model for the Bass Strait -30 m. <a href=https://dx.doi.org/10.26186/147043>https://dx.doi.org/10.26186/147043</a>, GA eCat Record 147043.&nbsp;</em></div><div><br></div><div><em>Dove, D., Nanson, R., Bjarnadóttir, L. R., Guinan, J., Gafeira, J., Post, A., Dolan, Margaret F.J., Stewart, H., Arosio, R., Scott, G. (2020). A two-part seabed geomorphology classification scheme (v.2); Part 1: morphology features glossary. Zenodo. <a href=https://doi.org/10.5281/zenodo.40752483>https://doi.org/10.5281/zenodo.4075248</a>; GA eCat Record 144305&nbsp;</em></div><div><br></div><div><em>Huang, Z., Nanson, R. and Nichol, S. (2022). Geoscience Australia's Semi-automated Morphological Mapping Tools (GA-SaMMT) for Seabed Characterisation. Geoscience Australia, Canberra. <a href=https://dx.doi.org/10.26186/146832>https://dx.doi.org/10.26186/146832</a>; GA eCat Record 146832 </em></div><div><em>&nbsp;</em></div><div><em>Nanson, R., Arosio, R., Gafeira, J., McNeil, M., Dove, D., Bjarnadóttir, L., Dolan, M., Guinan, J., Post, A., Webb, J., Nichol, S. (2023). A two-part seabed geomorphology classification scheme; Part 2: Geomorphology classification framework and glossary (Version 1.0) (1.0). Zenodo.<a href=https://doi.org/10.5281/zenodo.7804019>https://doi.org/10.5281/zenodo.7804019</a>; GA eCat Record 147818&nbsp;</em></div>

<div>This data product contains geospatial seabed morphology and geomorphology information for Flinders Reefs and Cairns Seamount (Coral Sea Marine Park). These maps are intended for use by marine park managers, regulators, the general public and other stakeholders. A nationally consistent two-part (two-step) seabed geomorphology classification system was used to map and classify the distribution of key seabed features. </div><div><br></div><div>In step 1, semi-automated GIS mapping tools (GA-SaMMT; Huang et al., 2022; eCat Record 146832) were applied to a bathymetry digital elevation model (DEM) in a GIS environment (ESRI ArcGIS Pro) to map polygon extents (topographic high, low, and planar) and to quantitatively characterise their geometries. Their geometric attributes were then used to classify each shape into discrete Morphology Feature types (Part 1: Dove et al., 2020; eCat Record 144305). In step 2, the seabed geomorphology was interpreted by applying additional datasets and domain knowledge to inform their geomorphic characterisation (Part 2: Nanson et al., 2023; eCat Record 147818). Where available, backscatter intensity, seabed imagery, seabed sediment samples and sub-bottom profiles supplemented the bathymetry DEM and morphology classifications to inform the geomorphic interpretations.</div><div><br></div><div>The Flinders Reefs seabed morphology and geomorphology maps were derived from an 8 m horizontal resolution bathymetry DEM compiled from multibeam surveys (FK200429/GA4861: Beaman et al., 2020; FK200802/GA0365: Brooke et al, 2020), Laser Airborne Depth Sounder (LADS), Light Detection and Ranging (LiDAR) and bathymetry supplied by the Australian Hydrographic Office.</div><div><br></div><div>A subset of the FK200802/GA0365 multibeam survey was gridded at 1 m horizontal resolution to derive the key morphology and geomorphology features at the top of Cairns Seamount (-35 to -66 m; within the upper mesophotic zone).</div><div><br></div><div>The data product and application schema are fully described in the accompanying Data Product Specification. </div><div><br></div><div><em>Beaman, R., Duncan, P., Smith, D., Rais, K., Siwabessy, P.J.W., Spinoccia, M. 2020. Visioning the Coral Sea Marine Park bathymetry survey (FK200429/GA4861). Geoscience Australia, Canberra. <a href=https://dx.doi.org/10.26186/140048>https://dx.doi.org/10.26186/140048</a>; GA eCat record 140048</em></div><div><br></div><div><em>Brooke, B., Nichol, S., Beaman, R. 2020. Seamounts, Canyons and Reefs of the Coral Sea bathymetry survey (FK200802/GA0365). Geoscience Australia, Canberra. <a href=https://dx.doi.org/10.26186/144385>https://dx.doi.org/10.26186/144385</a>; GA eCat record 144385</em></div><div><br></div><div><em>Dove, D., Nanson, R., Bjarnadóttir, L. R., Guinan, J., Gafeira, J., Post, A., Dolan, Margaret F.J., Stewart, H., Arosio, R., Scott, G. (2020). A two-part seabed geomorphology classification scheme (v.2); Part 1: morphology features glossary. Zenodo. <a href=https://doi.org/10.5281/zenodo.4075248>https://doi.org/10.5281/zenodo.4075248</a>; GA eCat Record 144305 </em></div><div><br></div><div><em>Huang, Z., Nanson, R. and Nichol, S. (2022). Geoscience Australia's Semi-automated Morphological Mapping Tools (GA-SaMMT) for Seabed Characterisation. Geoscience Australia, Canberra. <a href=https://dx.doi.org/10.26186/146832>https://dx.doi.org/10.26186/146832</a>; GA eCat Record 146832</em></div><div><br></div><div><em>Nanson, R., Arosio, R., Gafeira, J., McNeil, M., Dove, D., Bjarnadóttir, L., Dolan, M., Guinan, J., Post, A., Webb, J., Nichol, S. (2023). A two-part seabed geomorphology classification scheme; Part 2: Geomorphology classification framework and glossary (Version 1.0) (1.0). Zenodo. <a href=https://doi.org/10.5281/zenodo.7804019>https://doi.org/10.5281/zenodo.7804019</a>; GA eCat Record 147818 </em></div>