This record contains the substantive results of Geoscience Australia marine survey SS08/2005 to the SW margin of Australia. The survey was completed between 28 September and 20 October 2005 using Australia’s national facility research vessel Southern Surveyor. The survey included scientists from Geoscience Australia, CSIRO – Marine and Atmospheric Research, and Victoria Museum. The survey was co‐funded by Geoscience Australia and the Department of the Environment and Heritage (now the Department of the Environment, Water, Heritage and the Arts). The principal aims of the survey were to explore deep‐sea habitats and processes in submarine canyons on the SW margin, and examine the geology of the underlying Mentelle Basin as an assessment for its petroleum potential.

Faults of the Lapstone Structural Complex (LSC) underlie 100 km, and perhaps as much as 160 km, of the eastern range front of the Blue Mountains, west of Sydney, Australia. More than a dozen major faults and monoclinal flexures have been mapped along its extent. Debate continues as to the age of formation of the ~400 m or more of relief relating to the LSC, with estimates ranging from Palaeozoic to Pliocene. The results of an investigation of Mountain Lagoon, a small basin bound on its eastern side by the Kurrajong Fault in the central part of the LSC, favour a predominantly pre-Neogene origin. Drilling on the eastern margin of the lagoon identified 15 m of fluvial, colluvial and lacustrine sediments, overlying shale bedrock. The sediments are trapped behind a sandstone barrier corresponding to the Kurrajong Fault. Dating of pollen grains preserved in sediments at the base of this sediment column suggest that the fault-angle depression began trapping sediment in the Early to Middle Miocene. Strongly heated Permo-Triassic gymnosperm pollen in the same strata provides circumstantial evidence that sediment accumulation post-dates the ca. 18.8 Ma emplacement of the nearby Green Scrub basalt. Our data indicate that only 15 m of the 130 m of throw across the Kurrajong Fault has occurred during the Neogene suggesting a predominantly erosional exhumation origin for current relief at the eastern edge of the Blue Mountains plateau. Sedimentation since the Late Pleistocene appears to have been controlled largely by climatic processes, with tectonism exerting little or no influence.

A geological investigation was carried out by the writer. The aim was to check the previous mapping of the geology, and if necessary, to assist the Magnetician in locating a suitable site for magnetic observations. Some aspects of geomorphology, and the reconnaissance survey work carried out are discussed in this report.

During the summer of 1947, an expedition was despatched to Heard Island with the object of landing a party to spend about twelve months there. Geological work was undertaken by the writer. The results of this work are recorded in this report. These results include observations on the geomorphology of the island, and a description of the xenolithic ejectamenta collected from the tuffs of Rogers Head and Rogers Head Peninsula.

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.

Surveying of nearshore areas in the Vestfold Hills using high resolution multibeam swath bathymetry provides both a detailed digital bathymetric model and information on sediment acoustic backscatter. Combined with underwater video transects and sediment sampling, these data can be used to identify and map geomorphic units. Six geomorphic units identified in the survey region include: Rocky outcrops, sediment-floored basins, pediments, steep-sided valleys, scarps and sheltered embayments. In addition to geomorphic units, the data reveal sedimentary structures that provide insights into sediment transport and erosion in the area. Ice keel pits and scours are common while seafloor channels, scour depressions and sand ribbons indicate transport and deposition by wind-driven currents and oceanographic circulation. Gullies and sediment lobes on steep slopes indicate mass movement of sediment. The sheltered embayments preserve a mantle of boulder sand probably deposited by cold-based glaciers. Automated techniques utilizing the bathymetric grid and backscatter to map landforms are useful in defining reproducible boundaries between geomorphic units but cannot easily be adapted to accurately classify the variations in sea floor texture and structure imaged by these data.

The late Quaternary ice sheet/ice shelf extent in the George V Basin (East Antarctica) has been reconstructed through analyses of Chirp sub-bottom profiles, integrated with multi-channel seismic data and sediment cores. Four glacial facies, related to the advance and retreat history of the glaciated margin, have been distinguished: Facies 1 represents outcrop of crystalline and sedimentary rocks along the steep inner shelf and comprises canyons once carved by glaciers; Facies 2 represents moraines and morainal banks and ridges with a depositional origin along the middle-inner shelf; Facies 3 represents glacial flutes along the middle-outer shelf; Facies 4 is related to ice-keel turbation at water depths <500 m along the outer shelf. A sediment drift deposit, located in the NW sector of the study area, partly overlies facies 2 and 3 and its ground-truthing provides clues to understanding their age. We have distinguished: a) an undisturbed sediment drift deposit at water depth >775 m, with drape/sheet and mound characters and numerous undisturbed sub-bottom sub-parallel reflectors (Facies MD1); b) a fluted sediment drift deposit at water depth <775 m, showing disrupted reflectors and a hummocky upper surface (Facies MD2). Radiocarbon ages of sediment cores indicate that the glacial advance producing facies MD2 corresponds to the Last Glacial Maximum (LGM) and that during the LGM the ice shelf was floating over the deep sector of the basin, leaving the sediment drift deposit undisturbed at major depths (Facies MD1). This observation further implies that: a) glacial facies underneath the sediment drift were the result of a grounding event older than the LGM, b) this sector of the East Antarctic fringe was sensitive to sea-level rise at the end of the LGM; thus potentially contributing to meltwater discharge during the last deglaciation.

Probabilistic seismic hazard analyses in Australia rely fundamentally on the assumption that earthquakes recorded in the past are indicative of where earthquakes will occur in the future. No attempt has yet been made to assess the potential contribution that data from active fault sources might make to the modelling process, despite successful incorporation of such data into United States and New Zealand hazard maps in recent years. In this paper we review the limited history of paleoseismological investigation in Australia and discuss the potential contribution of active fault source data towards improving our understanding of intraplate seismicity. The availability and suitability of Australian active fault source data for incorporation into future probabilistic hazard models is assessed, and appropriate methodologies for achieving this proposed.

For the first time, the distribution of seabed geomorphic features has been systematically mapped over the Australian margin. Each of 21 feature types was identified using a new, 250 m spatial resolution bathymetry model and supporting literature. The total area mapped was >8.9 million km2 and included the seabed surrounding the Australian mainland and island territories of Christmas, Cocos (Keeling), Macquarie and Norfolk Islands. Of this total, the shelf is >1.9 million km2 (21.92%), the slope >4.0 million km2 (44.80%), and the abyssal plain/deep ocean floor >2.8 million km2 (32.20%). The rise covers 97,070 km2 or 1.08% of the margin. A total of 6,702 individual geomorphic features were mapped on the Australian margin. Plateaus have the largest surface area and cover 1.49 million km2 or 16.54%, followed by basins (714,000 km2; 7.98%), and terraces (577,700 km2; 6.44%), with the remaining 14 types each making up <5%. Reefs, which total 4,172 individual features (47,900 km2; 0.54%), are the most numerous type of geomorphic feature, principally due to the large number of individual coral reefs of the Great Barrier Reef. The geomorphology of the margin is most complex where marginal plateaus, terraces, trench/troughs and submarine canyons are present. Comparison with global seabed geomorphology indicates that the Australian margin is relatively under-represented in shelf, rise and abyssal plain/deep ocean floor area and over-represented in slope area, a pattern that reflects the mainland being bounded on three sides by passive continent-ocean rifted margins and associated numerous subsided marginal plateaus. Significantly, marginal plateaus on the Australian margin cover 20% of the total world area of marginal plateaus. The Australian margin can be divided into 10 geomorphic regions by quantifying regional differences in diagnostic features that can be used to infer broad-scale seabed habitats. The present study has application for the future management of Australia's ocean resources.

This record contains the raw Ground Penetrating Radar (GPR) data and scanned field notes collected on fieldwork at Old Bar and Boomerang Beaches, NSW for the Bushfire and Natural Hazards CRC Project, Resilience to Clustered Disaster Events on the Coast - Storm Surge. The data was collected from 3 - 5 March 2015 using a MALA ProEx GPR system with 250 MHz shielded and 100 MHz unshielded antennaes. The aim of the field work was to identify and define a minimum thickness for the beach and dune systems, and where possible depth to any identifiable competent substrate (e.g. bedrock) or pre-Holocene surface which may influence the erosion potential of incident wave energy. Surface elevation data was co-acquired and used to topographically correct the GPR profiles.