This study reports the findings of salt store and salinity hazard mapping for a 20-km wide swath of the Lindsay - Wallpolla reach of the River Murray floodplain in SE Australia. The study integrated remote sensing data, an airborne electromagnetics (AEM) survey (RESOLVE frequency domain system), and lithological and hydrogeochemical data obtained from a field mapping and drilling program. Maps of surface salinity, and surface salinity hazard identified Lindsay and Wallpolla Islands, and the lower Darling Floodplain as areas of high to extreme surface salinity hazard. In the sub-surface, salt stores were found in general to increase away from drainage lines in both the unsaturated and saturated zones. Beneath the Murray River floodplain, salt stores in both unsaturated and saturated zones are high to very high (100 to 300t/ha/m) across most of the floodplain. Sub-surface salinity hazard maps (incorporating mapped salt stores and lithologies, depth to water table and the hydraulic connectivity between the aquifers), identify Lindsay and Wallpolla Islands; the northern floodplain between Lock 8 and Lock 7; and northern bank of Frenchman's Creek as areas of greatest hazard. Overall, the new data and knowledge obtained in this study has filled important knowledge gaps particularly with respect to the distribution of key elements of the hydrostratigraphy and salinity extent across the Murray River and lower Darling floodplain. These data are being used to parameterise groundwater models for salinity risk predictions, to recalculate estimates of evapotranspiration for salt load predictions, address specific salinity management questions, and refine monitoring and management strategies.

Airborne electromagnetic (AEM) systems are increasingly being used for mapping conductivity in areas susceptible to secondary salinity, with particular attention on near-surface predictions (ie those in the top 5 or 10 metres). Since measured AEM response is strongly dependent on the height of both the transmitter loop and receiver coil above conductive material, errors in measurements of terrain clearance translate directly into significant errors in predicted near-surface conductivity. Radar altimetry has been the standard in airborne geophysical systems for measuring terrain clearance. In areas of agricultural activity significant artifacts up to five metres in magnitude can be present. One class of error, related to surface roughness and soil moisture levels in ploughed paddocks and hence termed the ?paddock effect?, results in overestimation of terrain clearance. A second class of error, related to dense vegetation and hence termed the ?canopy effect?, results in underestimation of terrain clearance. A survey example where terrain clearance was measured using both a radar and a laser altimeter illustrates the consequences of the paddock and canopy effects on shallow conductivity predictions. The survey example shows that the combination of the dependence of AEM response on terrain clearance and systematic radar altimeter artefacts spatially coincident with areas of differing land-use may falsely imply that land-use practices are the controlling influence on conductivity variations in the near surface. A laser altimeter is recommended for AEM applications since this device is immune to the paddock effect. Careful processing is still required to minimise canopy effects.

In a land management context, conductivity can be related to quantities such as salt store, ground water salinity, clay content, hydraulic permeability, degree of groundwater saturation or more generally to definition of regolith and bedrock units. These relationships open the way for the use of electromagnetic methods to measure subsurface conductivity. From the very early trials, efforts have been made to transform the measurements to conductivity. The real world presents a myriad of difficulties, that translate into errors and artifacts in 2D sections or 3D volumes produced from individual 1D conductivity transformation solutions. Reconciliation of AEM conductivity predictions with other spatial information presents a deceptively difficult challenge. A variety of improvements in the future will lead to a more accurate portrayal of conductivity in 3D.

Airborne electromagnetic (AEM) systems are increasingly being used for mapping conductivity in areas susceptible to secondary salinity, with particular attention on near-surface predictions (ie those in the top 5 or 10 metres). Since measured AEM response is strongly dependent on the height of both the transmitter loop and receiver coil above conductive material, errors in measurements of terrain clearance translate directly into significant errors in predicted near-surface conductivity. Radar altimetry has been the standard in airborne geophysical systems for measuring terrain clearance. In areas of agricultural activity significant artifacts up to five metres in magnitude can be present. One class of error, related to surface roughness and soil moisture levels in ploughed paddocks and hence termed the ?paddock effect?, results in overestimation of terrain clearance. A second class of error, related to dense vegetation and hence termed the ?canopy effect?, results in underestimation of terrain clearance. A survey example where terrain clearance was measured using both a radar and a laser altimeter illustrates the consequences of the paddock and canopy effects on shallow conductivity predictions. The survey example shows that the combination of the dependence of AEM response on terrain clearance and systematic radar altimeter artefacts spatially coincident with areas of differing land-use may falsely imply that land-use practices are the controlling influence on conductivity variations in the near surface. A laser altimeter is recommended for AEM applications since this device is immune to the paddock effect. Careful processing is still required to minimise canopy effects.

The GILMORE Project (Geoscience In Land Management and Ore System Research for Exploration) is a pilot study designed to assess methodologies and technologies for identifying mineral prospectivity and dryland salinity in areas of complex regolith cover (Lawrie et al., 2000). The project area (100 x 150 km) lies in the eastern part of the Murray-Darling Basin in central-west NSW and straddles the Gilmore Fault Zone, a major NNW-trending crustal structure that separates the Wagga-Omeo and the Junee-Narromine Volcanic Belts in the Lachlan Fold Belt. Included in the project area are tributaries of the Lachlan and the Murrumbidgee Rivers. A critical aspect of this research was to develop databases and a GIS to enable researchers to view and analyse complex datasets and their inter-relationships in both two and three dimensions. The GILMORE Project GIS consists of 11 CDs in 2 volumes. Volume 1 is comprised of 5 CDs and contains airborne electromagnetic (AEM), magnetic and gamma-ray spectrometric geophysical datasets. These are included in point located (line) form as ASCII column format files, and in gridded form as ERMapper format grids. These data have already been released. Volume 2 comprises of 6 CDs containing data in ESRI\222s ArcInfo and ArcView for mat. Each CD has an ArcView Project accessing colour geophysical images (created in ERMapper), ArcInfo polygon, point and line coverages, ArcView shape files, with links to gif images, photos and .dbf files. The GIS will also be released in MapInfo format.

In addition to typical seafloor VHMS deposits, the ~3240 Ma Panorama district contains contemporaneous greisen- and vein-hosted Mo-Cu-Zn-Sn occurrences that hosted by the Strelley granite complex, which drove VHMS circulation. High-temperature alteration zones in volcanic rocks underlying the VHMS deposits are dominated by quartz-chlorite±albite assemblages, with lesser low-temperature quartz-sericite±K-feldspar assemblages, typical of VHMS hydrothermal systems. Alteration assemblages associated with granite-hosted greisens and veins, which do not extend into the overlying volcanc pile, include quartz-topaz-muscovite-fluorite and quartz-muscovite(sericite)-chlorite-ankerite. Fluid inclusion and stable isotope data suggest that the greisens formed from high temperature (~590C), high salinity (38-56 wt % NaCl equiv) fluids with high densities (>1.3 g/cm3) and high -18O (9.3±0.6-), which are compatible with magmatic fluids evolved from the Strelley granite complex. Fluids in the volcanic pile (including the VHMS ore-forming fluids) were of lower temperature (90-270C), lower salinity (5.0-11.2 wt % NaCl equiv), with lower densities (0.88-1.01 g/cm3) and lower -18O (-0.8±2.6), compatible with evolved Paleoarchean seawater. Fluids that formed the quartz-chalcopyrite-sphalerite-cassiterite veins, which are present within the upper granite complex, were intermediate in temperature and isotopic composition (T = 240-315C; -18O = 4.3±1.5-) and are interpreted to indicate mixing between the two end-member fluids. Evidence of mixing between evolved seawater and magmatic-hydrothermal fluid in the granite complex, along with a lack of evidence for a magmatic component in fluids from the volcanic pile, suggest partitioning of magmatic-hydrothermal from evolved seawater hydrothermal systems in the Panorama VHMS system, interpreted as a consequence swamping of the system by evolved seawater or density contrasts.

An inventory of saline water disposal basins, Murray Basin : volume 3 additional basins in South Australia, Victoria and New South Wales 1998.

The identification of suitable abiotic surrogates for biological diversity requires the collection of both physical and biological data. However, logistical constraints often preclude experimental designs that incorporate spatial and temporal replication. Given the quite limited resources normally available for surveys, the investigation of appropriate surrogates involves a trade-off between overall spatial coverage and replication. We have completed a survey in Jervis Bay in which environmental and infaunal data were collected contemporaneously in order to be combined with similar data from a previous winter survey (survey number GA309) to investigate variation across seasons. Because there will be a certain error in sampling at the exact location as the previous survey, the survey design also required that replicate samples be taken at a set number of stations in order to investigate fine-scale variability (at the scale of metres). We used grabs to collect paired geochemical and biological samples from thirty-two stations in a defined grid near Darling Rd; at eight of these stations we deployed three pairs of grabs to investigate fine-scale variability. Due to good weather and extra ship time available, we also deployed a CTD to investigate vertical temperature and salinity profiles at each station in the Darling Rd grid, as well as at stations throughout the entire bay. Samples are expected to be processed and analysed by late 2009, but preliminary results indicate that most physical variables and infaunal assemblages varied between seasons. In addition, variation among infaunal assemblages seems greater among stations (hundreds of meters) than within replicates at stations (meters).

The map shows regions favourable for calcrete-hosted uranium mineral systems. For a more detailed description of selection method see Jaireth et al. (2013).

The map shows salt lake regions favourable for potash deposits. For a more detailed description of selection method see Jaireth et al (2013)