This study assessed the geochemical indicators for carbonatite-associated and alkaline igneous REE mineral systems based on state-scale ASTER data for Western Australia and the National Geochemical Survey of Australia. In the latter we applied discrete field models obtained by attributing catchment outlet sediment geochemical data to their catchment basins. The cerium data was found to be a suitable proxy for the main features of REE distribution across the continent. In general, this provided a well-expressed positive correlation between identified catchments with anomalous (elevated) Ce and the mineral occurrences and deposits that they contained but not all REE deposits were identified by these methods. The study also included more detailed mineral mapping using the recently released ASTER geoscience map of Western Australia (WA). A study of the relatively well exposed Yangibana 'ironstone' dykes in the Gascoyne Province of Western Australia showed relatively good correlations with known REE occurrences for the AlOH Group Composition, MgOH Group Composition and Ferrous Iron Content in MgOH/carbonate ASTER products. However, no well defined correlations were observed for Mt Weld, Ponton and Cummins Range all of which occur under cover. The ASTER SWIR products have difficulty detecting the types of minerals present in alteration zones surrounding these carbonatites. Some of these minerals may be detected with the ASTER thermal infrared geoscience products which were not available at the time of this study. These products will include a silica index (e.g. for quartz, feldspars, Al-clays), a carbonate index (e.g. for calcite, dolomite, magnesite, siderite, ankerite) and a mafic group index (e.g. for pyroxenes, garnets, olivine, epidote, chlorite, calcite, magnesite, dolomite). However, the lower resolution of the thermal infrared bands (~90 m) may still make it difficult to detect carbonatite-associated mineralisation. Finally, the ASTER data for the Brockman (Hastings) alkaline igneous REE deposit was also examined. The mineralised unit of this deposit only reaches a maximum width of 35 m and so, once again, proved difficult to detect with ASTER. However, the ASTER maps readily highlighted the contact between the Olympio Formation to the east with the Biscay Formation to the west and demonstrated the mapping capabilities of the ASTER products where the lithologies are relatively well exposed. In order to overcome the problem of only sampling the surface, we combined the ASTER data with the regional magnetic data because the magnetic signal is derived from a greater depth. As many carbonatite complexes are surrounded by mafic alkaline rocks, they often show up as a magnetic bull's eye combined with a gravity low and ringed by a gravity high.

Archived imagery

Increased loads of land-based pollutants associated with land use change are a major threat to coastal-marine ecosystems globally. Identifying the affected areas and the scale of influence on marine ecosystems is critical to assess the ecological impacts of degraded water quality and to inform planning for catchment management and marine conservation. Studies using remotely-sensed data have contributed to our understanding of the occurrence and extent of influence of river plumes, as well as to assess exposure of ecosystems to river-borne pollutants. However, refinement of plume modelling techniques is required to improve risk assessments. We developed a novel approach to model exposure of coastal-marine ecosystems to river-borne pollutants. The model is based on supervised classification of true-colour satellite imagery to map the extent of plumes and to qualitatively assess the dispersal of pollutants in plumes. We use the Great Barrier Reef (GBR) to test our approach. We combined frequency of plume occurrence with spatially-distributed loads (based on a cost-distance function) to create maps of exposure to suspended sediment and dissolved inorganic nitrogen. We then compared annual exposure maps (2007-2011) to assess inter-annual variability in the exposure of coral reefs and seagrass beds. Our findings indicate that classification of true colour satellite images is useful to map plumes and to qualitatively assess exposure to river-borne pollutants. This approach should be considered complementary to remote sensing methods based on ocean colour products used to characterise surface water in plumes. The proposed exposure model is useful to study the spatial and temporal variation in exposure of coastal-marine ecosystems to riverine plumes. Observed inter-annual variation in exposure of habitats to pollutants stresses the need to incorporate the temporal component in exposure and risk models.

Fresh groundwater resources are a highly valuable commodity, particularly in semi-arid to arid landscapes where annual precipitation is low and surface water is scarce. Water security, often achieved through the development of groundwater resources, is a high priority for rural communities within these water-limited landscapes. However this is often at the expense of the environment when alterations to the groundwater system, often in conjunction with drought conditions, can detrimentally impact floodplain and riparian vegetation structure and function. Remote-sensing methods can be used to detect such changes in vegetation. In this study, a multi-temporal Landsat Normalised Difference Vegetation Index (NDVI) approach was used to detect changes in riparian and floodplain vegetation in the Lower-Darling floodplain, NSW, Australia. When integrated with surface and subsurface data, these changes provided insight into how surface water availability and subsurface geological and hydrogeological characteristics influenced vegetation distribution and behaviour at multiple scales. It was found that while the availability of water resources was the primary driver of changes in vegetation canopy dynamics, this availability was strongly influenced by both tectonic and hydrogeological processes. These findings were of particular importance when considering the suitability of groundwater development options and they have implications for future groundwater assessment studies.

The 1996 Yampi Shelf airborne laser fluorosensor (ALF) survey was flown in two sorties on the 1st December 1996. Twenty three lines were acquired at 1km spacing in a N-S direction at a flying height of 100 m. Line lengths ranged from 20 km to 23.6 km, with a total of 488.7 km acquired. Of the 343,563 spectra recorded, 57 were interpreted as having confident fluors (165 fluors per million spectra). These were mostly low intensity fluors with only one having a F/R ratio above 0.30. The fluors were found mostly in the eastern half of the survey in broad clusters.

The Haydn airborne laser fluorosensor (ALF) survey is located in the Vulcan Sub-basin, Timor Sea. The survey was flown in two sorties on the 2nd December 1996. Sixty-five lines were acquired at 400 m spacing in a NW-SE orientation with a total of about 550 square kilometres acquired. Seventeen lines were acquired at 1200 m spacing in the orthogonal NE-SW direction. The NW-SE lines were about 21.35 km long while the NE-SW lines were about 26 km long. Many types of noise were found on the ALF records and these were rejected during the manual checking phase of fluor selection.Of the 1,529,484 spectra recorded, only 21 were interpreted as having confident fluors. No significant fluorescence clusters were observed. Only 4 fluors were found with a F/R ratio above 0.30.

The Browse Basin airborne laser fluorosensor (ALF) MkII survey was flown in 1989. The MkII system used a 308nm laser wavelength, which is longer than the 266nm used in the later MkIII system. The Raman peak wavelength is 344nm (293nm MkIII) and the fluorescence region is 370nm to 580nm (320nm to 580nm MkIII). 32 lines were acquired at about 5,000m spacing in a NNE-SSW orientation and a flying height of 100m. A total of 133,125 spectra were collected at an average spacing of 16m to 25m. About 2,270 km of line data were acquired. Each recorded spectrum is the average (or sum) of ten detected spectra. The averaging was done to reduce the data recording rate, which was limited by the available hardware. The survey was interpreted using the ALF Explorer application that consists of a database linked to a set of data processing, analysis and display modules. A total of 776 fluors were interpreted out of the 133,125 recorded spectra. The fluorescence response over most of the survey area consisted mostly of relatively low confidence fluors. High intensity fluors are located over Scott Reef but are probably caused by the reef material fluorescing.

The Barrow Sub-basin airborne laser fluorosensor (ALF) MkII survey was flown in 1989 by BP. The survey was designed to detect natural oil seepage over a region of the Barrow and Dampier sub-basins in the Carnarvon Basin, Western Australia, in an effort to refine the petroleum prospectivity assessment. The survey extended in a NE-SW direction for nearly 350km with an average width of about 100km. The line spacing was 4.5km and a total of 328,565 fluorosensor spectra were recorded. This report presents a re-interpretation of the BP data by Signalworks Pty Ltd using the ALF Explorer? software. A total of 1,451 fluors were interpreted out of the 328,565 recorded spectra. This is an average fluor density of 4.42 fluors per thousand spectra. The fluorescence response over most of the survey area consisted mainly of relatively low confidence fluors (compared to the more reliable MkIII survey data). High intensity fluors are located near islands but are probably caused by the exposed island material fluorescing. While fluor density variations can be seen on the fluor map the geological implications are not clear. Because of its susceptibility to noise, the MkII ALF system produces less confident fluor maps than the MkIII system. Some mapped fluor density variations may be influenced by sea state or water property variations.

The Timor Gap airborne laser fluorosensor (ALF) MkII survey was flown in 1989 by BP over the northern Bonaparte Basin (Sahul Platform, Sahul Syncline and Malita Graben). The MkII system used a 308nm laser wavelength, which is longer than the 266nm used in the later MkIII system. The Raman peak wavelength is 344nm (293nm MkIII) and the fluorescence region is 370nm to 580nm (320nm to 580nm MkIII). 208 lines were acquired at about 1,900m spacing in a NW-SE orientation and a flying height of 100m. A total of 1,860,650 spectra were collected at an average spacing of 16.9m to 28.5m. About 36,000 km of line data were acquired. Each recorded spectrum is the average (or sum) of ten detected spectra. The averaging was done to reduce the data recording rate, which was limited by the available hardware. The survey was interpreted using the ALF_Explorer software that consists of a database linked to a set of data processing, analysis and display modules. A total of 392 fluors were interpreted out of the 439,972 recorded spectra. 68 of these are located in a single patch near the Jabiru Field. This patch contains many very large fluors.

The WA-260-P airborne laser fluorosensor (ALF) survey was flown by World Geoscience in the Timor Sea in October 1997 for BHP Petroleum and joint venture partners using the ALF MkIII system. The survey was designed to detect natural oil seepage over the permit in an effort to refine the petroleum prospectivity assessment. The survey covers a triangular area over the northern two thirds of the permit and extends about 60km north to south and nearly 50km east to west at its widest section in the south. This report is a re-interpretation of the World Geoscience data by Signalworks Pty Ltd using the ALF Explorer software. A total of 285 fluorescence anomalies (fluors) were picked out of the 1,751,550 recorded spectra in the final interpretation. This is an average fluor density of 0.16 fluors per thousand spectra. The fluor distribution across permit WA-260-P is relatively uniform, with no strong oil seepage patterns evident. A possible band of more intense fluors lies on an E-W trend to the south of the Buller-1 and Cleia-1 wells. The scattered distribution of detected fluors may be an indication of a working petroleum system. The known accumulations covered by the survey do not directly correspond with distinct clustering of fluors.