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  • This suite of products contains topographical relief generated from raw LiDAR data and covers the Southern extent of the Murray Darling Basin within the proximity of the Murray River. LiDAR (Light Detection and Ranging) is an airborne remote sensing technique for rapid collection of terrain data. The sensor used for this LiDAR project collected XYZ and Intensity data for 2 returns, first and last (ground) return by bouncing a pulse from the aircraft to the surface that enables the height and intensity values to be calculated. Height data within the first and last return raw LiDAR data was processed into 1m pixel DEMs. The intensity data with the first return raw LiDAR data was processed into a 1m pixel intensity image. The 1m cell size products, due to their large file sizes, are stored as 2km by 2km tiles to help facilitate data management and processing. The complete study area, covering 1.7million hectares, contains 5,288 of these tiles. All the above derived products were initially created as value added products by the Land Information Group (LIG), of the Department of Sustainability and Environment (DSE), Victoria. This acquisition was commissioned by Murray Darling Basin Commission (MDBC) and participating Consortium members including: Barmah Millewa Forum Murray Irrigation Limited, NSW Department of Infrastructure, Planning and Natural Resources - Deniliquin North Central Catchment Management Authority (CMA) Department of Urban Affairs and Planning, NSW Goulburn Broken CMA, Vic North East CMA, Vic

  • Compilation of new and existing data can be used to show systematic variations in initial ore-related Pb isotope ratios and derived parameters for the Lachlan and Delamerian orogens of southeast Australia. In addition to mapping tectonic boundaries and providing genetic context to mineralising processes, these variations map mineralised provinces at the orogenic scale and can provide vectors to ore at the district scale. In New South Wales and Victoria, mapping using a parameter termed the 'Lachlan Lead Index' (LLI), which measures relative mixing between crustal- and mantle-derived Pb using the curves of Carr et al. (1995, Economic Geology 90:14671505), clearly demarcates the boundary between the Eastern and Central Lachlan provinces, and seems to identify boundaries between zones within the Western Lachlan Province of Victoria. The LLI also maps the extent of the isotopically juvenile Macquarie 'Arc' in New South Wales. However, rocks in the Rockley-Gulgong Belt, initially mapped as part of the Macquarie Arc, have a more evolved isotopic character, suggesting that these rocks are not part of the Macquarie Arc. This interpretation supports recent mapping that casts doubt on the attribution of this belt to the Macquarie Arc (Quinn, et al., 2014, Journal of the Geological Society of London 171:723736). The LLI has also identified small exposures of Ordovician volcanic rocks, well removed from the main Macquarie Arc, as possible correlates to this arc, with potential to host porphyry and epithermal deposits. Metallogenically, porphyry Cu-Au deposits in the Macquarie Arc are characterised by juvenile Pb. In contrast, Sn and Mo deposits in the Central Lachlan Province (i.e., the Wagga tin belt) are characterised by highly evolved Pb even though these deposits formed over 30 million years. Moreover, the Pb isotope data suggest that the original interpretation that copper deposits in the Girilambone district are volcanic-associated massive sulfide deposits was correct and that these deposits formed in a back-arc to the Macquarie Arc at ~480 Ma. In the Mount Read Volcanics of western Tasmania, all deposits appear to cluster along the same growth curve. However, when divided according to age (i.e., Cambrian (~500 Ma) versus Devonian (~360 Ma)), spatial patterns are visible in 206Pb/204Pb data. For Cambrian deposits 206Pb/204Pb decreases overall to the southeast, although low values are also present in the far south (i.e., Elliott Bay) and northeast. The most highly mineralised central part of the belt seems to be broadly associated with the zone of highest 206Pb/204Pb. Variations in 206Pb/204Pb for Devonian deposits broadly mimic the patterns seen for the Cambrian deposits. More importantly, a district-scale pattern in 206Pb/204Pb is present in the Zeehan district. Isotopically, the Sn-dominated core of the Zeehan district (e.g. Queen Hill and Severn deposits) is characterised by high 206Pb/204Pb, which decreases outward into the Zn-Pb-Ag-dominated peripheries. Lead isotope distribution patterns can potentially be used as an ore vector in this and other intrusion-centered mineral systems.

  • Analysis of the distribution patterns of Pb isotope data from mineralised samples using the plumbotectonic model of Carr et al. (1995), which invokes mixing between crustal and mantle reservoirs, indicates systematic spatial patterns that reflect major metallogenic and tectonic boundaries in the Lachlan and Delamerian orogens in New South Wales and Victoria. This distribution pattern accurately maps the boundary between the Central and Eastern Lachlan. The Central Lachlan is characterised by Pb isotope characteristics with a strong crustal signature, whereas the Eastern Lachlan is characterised by variable crustal and mantle signatures. The Macquarie Arc is dominated by Pb with a mantle signature: known porphyry Cu-Au and high sulphidation epithermal Au-Cu deposits in the arc are associated with a zone characterised by the strongest mantle signatures. In contrast, granite-related Sn deposits in the Central Lachlan are characterised by the strongest crustal signatures. The Pb isotope patterns are broadly similar to Nd isotope model age patterns derived from felsic magmatic rocks, although a lower density of Nd isotope analyses makes direct comparison problematic. The two reservoirs identified by Carr et al. (1995) do not appear to be isotopically linked: the crustal source was not formed via extraction from the mantle source. Rather, the two reservoirs must have formed separately. The mantle reservoir may have been sourced from a subducting proto-Pacific plate, whereas the crustal reservoir is most likely to be extended Australian crust. The data allow the possibility that the proto-Pacific mantle source was isotopically linked to the western Tasmanian crustal source. Comparison of Pb isotope data from the Girilambone district (e.g., Tritton and Avoca Tank deposits) with those from the Cobar district in north central New South Wales indicates a less radiogenic signature, and probably older age, for deposits in the Girilambone district. Hence, a syngenetic volcanic-associated massive sulphide origin for these deposits is preferred over a syn-tectonic origin. The data are also consistent with formation of the Girilambone district in a back-arc basin inboard from the earliest phase of the Macquarie Arc.

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    The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. The terrestrial dose rate grid is derived as a linear combination of the filtered K, U and Th grids. A low pass filter is applied to this grid to generate the filtered terrestrial dose rate grid. This GSNSW Exploration NSW Area J Cobar Nymagee total count grid geodetic has a cell size of 0.00049 degrees (approximately 50m) and shows the terrestrial dose rate of the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999. The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance.

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    The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric potassium grid has a cell size of 0.00049 degrees (approximately 50m) and shows potassium element concentration of the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999 in units of percent (or %). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance.

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    The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric thorium grid has a cell size of 0.00049 degrees (approximately 50m) and shows thorium element concentration of the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999 in units of parts per million (or ppm). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance.

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    Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This GSNSW Exploration NSW Area J Cobar Nymagee magnetic first vd grid geodetic is a first vertical derivative of the Total Magnetic Intensity grid for the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999. This grid has a cell size of 0.00049 degrees (approximately 50m). The grid has units of nanoTesla per km (or nT/km). The data used to produce the TMI grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance. A Fast Fourier Transform (FFT) process was applied to the original grid to calculate the first vertical derivative grid.

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    Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This GSNSW Exploration NSW Area J Cobar Nymagee magnetic grid geodetic has a cell size of 0.00049 degrees (approximately 50m). The units are in nanoTesla (or nT). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance.

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    The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This radiometric uranium grid has a cell size of 0.00049 degrees (approximately 50m) and shows uranium element concentration of the GSNSW Exploration NSW Area J, Cobar-Nymagee merge, 1999 in units of parts per million (or ppm). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance.

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    Total magnetic intensity (TMI) data measures variations in the intensity of the Earth's magnetic field caused by the contrasting content of rock-forming minerals in the Earth crust. Magnetic anomalies can be either positive (field stronger than normal) or negative (field weaker) depending on the susceptibility of the rock. The data are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose. This magnetic grid has a cell size of 0.00049 degrees (approximately 50m).The data are in nanoTesla (or nT). The data used to produce this grid was acquired in 1998 by the NSW Government, and consisted of 70181 line-kilometres of data at 250m line spacing and 60m terrain clearance. The data has had a variable reduction to the pole applied to centre the magnetic anomaly over the magnetised body. The VRTP processing followed a differential reduction to pole calculation up to 5th order polynomial. Magnetic inclination and declination were derived from the IGRF-11 geomagnetic reference model using a data representative date and elevation representative of the survey.