Geoscience Australia carried out a marine survey on Carnarvon shelf (WA) in 2008 (SOL4769) to map seabed bathymetry and characterise benthic environments through colocated sampling of surface sediments and infauna, observation of benthic habitats using underwater towed video and stills photography, and measurement of ocean tides and wavegenerated currents. Data and samples were acquired using the Australian Institute of Marine Science (AIMS) Research Vessel Solander. Bathymetric mapping, sampling and video transects were completed in three survey areas that extended seaward from Ningaloo Reef to the shelf edge, including: Mandu Creek (80 sq km); Point Cloates (281 sq km), and; Gnaraloo (321 sq km). Additional bathymetric mapping (but no sampling or video) was completed between Mandu creek and Point Cloates, covering 277 sq km and north of Mandu Creek, covering 79 sq km. Two oceanographic moorings were deployed in the Point Cloates survey area. The survey also mapped and sampled an area to the northeast of the Muiron Islands covering 52 sq km. cloates_3m is an ArcINFO grid of Point Cloates of Carnarvon Shelf survey area produced from the processed EM3002 bathymetry data using the CARIS HIPS and SIPS software

This dataset contains species identifications of molluscs from shell grit and sediments collected during survey SOL5463 (R.V. Southern Surveyor, 3-31 May 2012). Sediments were collected with a Smith Mac grab and processed in the GA laboratory. Sediment samples from two grabs contained many mollusc shells, some intact, and these were lodged at the Museum and Art Gallery of the Northern Territory (MAGNT). Species-level identifications were undertaken by Dr Richard Willan at the MAGNT and were delivered to Geoscience Australia on the 19 September 2012. See GA Record 2012/66 for further details on survey methods and specimen acquisition. Data is presented here exactly as delivered by the taxonomist, and Geoscience Australia is unable to verify the accuracy of the taxonomic identifications. Note that all specimens were identified from dead material and shell fragments. Specimens that were alive upon collection were processed separately with infaunal samples.

An interpretation of SIMS O isotope analysis and LA-MC-ICP-MS Lu-Hf analyses of zircons from the Rum Jungle Complex, northern Australia

Groundwater dependent ecosystems (GDEs) are an important feature of the Australia landscape and as need to be incorporated into water management to maintain their persistence. However the first step to ensuring sustainable management of GDEs is the identification of such communities. With recent technological advances in remote sensing, identification of GDEs is becoming more commonly achieved through temporal analysis of biophysical properties detected from satellite imagery, for example as used in the National Atlas of Groundwater Dependent Ecosystems. However, many of these remote sensing studies only concentrate on surface processes and fail to integrate the spatial and temporal dynamics of these communities with subsurface processes such as depth to watertable, groundwater quality, groundwater flow paths and recharge zones. In this study, LiDAR canopy digital elevation model and foliage projected cover data were combined with Landsat imagery in order to characterise the spatial and temporal behaviour of woody vegetation in the Lower Darling Floodplain, New South Wales. This multi-temporal data was then combined with hydrogeological, hydrogeochemical and hydrogeophysical data to assess the relative importance of hydrological processes and groundwater characteristics. Central to the approach was the use of airborne electromagnetics which provided a 3-dimensional context to otherwise point-based borehole data. Through these multiple lines of evidence, two types of groundwater dependent vegetation communities were identified. In both classes vegetation was concluded to be utilising groundwater within the shallow unconfined aquifer, however the distinction was the degree of connectivity with underlying aquifers through either an absence of the regional aquitard or connection via faults. This study highlights the importance of integrating remote sensing with both surface and subsurface data to gain an improved understanding of vegetation dynamics and groundwater dependency. These findings are being used to assess the suitability of proposed groundwater-development options in the study area, and have implications for riparian vegetation management more broadly.

In the literature of remote sensing image analysis, an endmember is defined as a pixel containing only one land cover substance. However, with the varying resolutions of available sensors, in most cases a single pixel in a satellite image contains more than one type of land cover substance. One challenge is to decompose a pixel with mixed spectral readings into a set of endmembers, and estimate the corresponding abundance fractions. The linear spectral unmixing model assumes that spectral reading of a single pixel is a linear combination of spectral readings from a set of endmembers. Most linear spectral unmixing algorithms rely on spectral signatures from endmembers in pre-defined libraries obtained from previous on-ground studies. Therefore, the applications of these algorithms are restricted to images whose extent and acquisition time coincide with those of the endmember library. We propose a linear spectral unmixing algorithm which is able to identify a set of endmembers from the actual image of the studied area. Existing spectral libraries are used as training sets to infer a model which determines the class labels of the derived image based endmembers. The advantage of such approach is that it is capable of performing consistent spectral unmixing in areas with no established endmember libraries. Testing has been conducted on a Landsat7 ETM+ image subset of the Gwydir region acquired on Jun 22, 2008. Three types of land cover classes: bare soil, green vegetation and non-photosynthetic are specified for this test. A set consisting of 150 endmember samples and a number of ground abundance observations were obtained from a corresponding field trip. The study successfully identified an endmember set from the image for the specified land cover classes. For most test points, the spectral unmixing and estimation of the corresponding abundance are consistent with the ground validation data.

Understanding how land cover responds to natural and anthropogenic drivers is critical as increasing population, climate fluctuations and competing land uses place increased pressure on both natural and food/fibre production systems. In 2011 Geoscience Australia released Version 1 of the Dynamic Land Cover Dataset (DLCDv1)[1] which consisted of a ISO 19144-2 land cover classification based on 8 years of 250 metre Moderate Resolution Image Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) time series [1]. Whereas Version 1 was a synoptic overview of land cover, Version 2 of the DLCD provides a series of land cover maps updated on an annual basis to enable resource managers, decision makers and biophysical modelers to track the change in land cover on a systematic basis.

For many basins along the western Australian margin, knowledge of basement and crustal structure is limited, yet both play an important role in controlling basin evolution. To provide new insight into these fundamental features of a continental margin, we present the results of process-oriented gravity modelling along a NW-SE profile across the Browse Basin through the Brecknock field. Process-oriented gravity modelling is a method that considers the rifting, sedimentation and magmatism that led to the present-day gravity field. By backstripping the sediment load under different isostatic assumptions (i.e. range of flexural rigidities), the crustal structure associated with rifting can be inferred. Combining the gravity anomalies caused by rifting and sedimentation and comparing them to observed gravity provides insight into the presence of magmatic underplating, the location of the continent-ocean boundary and the thermal history of a margin. For an effective elastic thickness of 25 km, backstripping syn- and post-rift sediments (Jurassic and younger) along the Browse Basin profile suggests moderate Jurassic stretching (beta-1-2) and shows that rifting and sedimentation generally explain the observed free-air gravity signature. The gravity fit is reasonable for most of the Scott Plateau and Caswell Sub-basin, but over the Leveque Shelf and Wilson Spur, predicted gravity is less than observed and predicted Moho is also shallower than suggested by seismic refraction data. These misfits suggest the presence of magmatic underplating beneath the Leveque Shelf and outermost parts of the basin, an inference that has mixed support from refraction and crustal-scale seismic reflection data.

This layer is part of Vicmap Elevation 10-20 Contours and Relief, a subset of Vicmap Elevation. It contains topographical relief features represented by lines. Data has been derived from Land Victoria's State Digital Map Base topographic data and converted from Microstation .DGN format to Arc/Info format.

Geoscience Australia has synthesised data for 18 wells in the Petrel Sub-basin as part of an integrated CO2 geological storage assessment of the sub-basin. The well folio summarises in graphic form key stratigraphic, biostratigraphic, petrophysical (calculated porosity and permeability) and seismic interpretations in composite well log plots at 1:3500 scale All data used are either publicly available or newly generated as part of the present study.

This Forum consisted of short and sharp 3 min presentations on a range of topics.