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.

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

High-quality, regional seismic data collected on the continental margin of southern New South Wales indicate that the margin lacks major basin development, consistent with its interpretation as an upper plate margin. The most striking structural feature is a mid-slope graben or half graben which is bounded on its eastern (seaward) side by a westerly-dipping fault system and a basement ridge. The half-graben contains up to 2.2 seconds TWT (~2500 m) of sediment, including syn-rift deposits possibly as old as Late Jurassic. A seaward-thickening wedge of sediment overlies a generally flat basement surface beneath the shelf. This contrasts with large areas of the lower continental slope which are essentially free of sediment. Sediment thicknesses beneath the Tasman Sea abyssal plain reflect basement structure. The greatest thickness occurs next to the foot of the slope where sediment loading has produced flexuring in either oceanic or thinned-continental crust. Overall, the petroleum potential of the margin (excluding the pre-rift Sydney Basin rocks) appears to be low.

An earthquake occurred without warning at 10:27 am on 28 December 1989 (local time) causing loss of life in the city of Newcastle, New South Wales, Australia, the first earthquake to cause fatalities in Australia since European settlement. The magnitude is estimated to have been 5.6 on the Richter scale. Earthquakes of this size occur on average about once every eighteen months in Australia. A single aftershock was recorded on a network of ten seismographs installed on 29 December in and around Newcastle; it had a magnitude of 2.1. The focal depth of the mainshock was 11.5±0.5 km and of the aftershock 13.5±0.8 km, which is beneath the Permian sediments of the Sydney Basin. The epicentres of both earthquakes are coincident within the error bounds and are some 15 km from the centre of damage in the City. The damage in Newcastle was made worse by an underlying thin layer of alluvium which magnified the ground motion substantially. A fault-plane solution indicates that the earthquake had a thrust mechanism with nodal planes striking in a NW-SE direction, parallel to the mapped surface faults in the region. Limited strong motion data were recorded, but not close to the epicentre.

The Cobar Basin in western New South Wales formed by sinistral transtension in the latest Silurian to late Early Devonian and evolved through a syn-rift phase of brittle upper crustal faulting and subsidence followed by a post-rift sag phase of passive subsidence which can also be recognised in other Early Devonian stratotectonic elements in western New South Wales. Basin evolution was controlled by regional faults splaying off the Gilmore Suture and the Kiewa Fault. The Cobar Basin was largely inverted - 400 Ma ago with reversal of movement (dextral transpression) on synsedimentary north-northwest-trending strike-slip/oblique-slip faults and on west-northwest-trending dip-slip faults. These faults controlled the partitioning of deformation in surface rocks into a high-strain Zone I developed above a half positive flower structure in the eastern part of the basin, and a lower strain Zone 2 developed above a flat detachment in the central part of the basin. Shortcut faults developed during inversion are the most likely structural targets for sulphide and gold accumulation which is structurally controlled and syntectonic metahydrothermal in origin. Some of these faults have experienced strike-slip faulting as well as contractional movement.

The Gilmore Fault Zone is a long-lived imbricate fault system separating the Wagga Metamorphic Belt from the Tumut Block in the Palaeozoic Lachlan Fold Belt. Structures within the fault zone indicate dominantly sinistral transpressional movements during regional deformation in the Siluro-Devonian and mid-Devonian and/or Carboniferous. These movements, in response to lateral compression, resulted in the Wagga Metamorphic Belt being thrust over the Tumut Block. Dextral strike-slip movement may be inferred during Early Silurian regional deformation and subsequent extension. Common structural and metamorphic histories, and lithological correlation of rock units straddling the fault zone, indicate that the Gilmore Fault Zone was not a terrane boundary in the Late Ordovician or Early Silurian. Differences in geophysical expression and crustal composition across the southern part of the zone would be explained if the zone is a reactivated basement fault which corresponds, in part, to an older terrane boundary. The fault zone is interpreted as a splay off a gently west-dipping mid-crustal detachment.

The Permian Yessabah Limestone, a thick crinoidal limestone unit, appears abruptly in the stratigraphic succession over a large area of the Hastings Block in northeastern New South Wales, disconformably overlying clastic rocks with sharply contrasting facies associations. The formation is part of a thick depositional sequence that began with a major sea-level fall at the end of the Carboniferous. The sea-level fall produced a major basinward shift in facies causing rejuvenation of streams and the deposition of braided-stream gravels in the onshore areas while a mass-movement association, the Parrabel Beds, was deposited offshore in the deep basin (the lowstand systems tract). The Yessabah Limestone was deposited as part of the transgressive systems tract in a shallow-marine high-energy environment as sea level again began to rise. The highstand systems tract then prograded over the Yessabah Limestone in the form of a distal turbidite association , the Warbro Formation and associated units, as sea level reached its maximum. The growth of both crinoids and bryozoa was prolific; their two distinctive faunal assemblages alternately dominated the sea floor, producing thick units of well-washed crinoid-rich limestone followed by a bryozoan-rich unit. As sea level rose, conditions became unsuitable for carbonate deposition and the area was again invaded by clastic sediments, forming a distal turbidite association that prograded across the limestones as part of the highstand systems tract.

Lake George is a fluctuating closed lake in the eastern highlands of Australia. Groundwater in the 932 km2 catchment is mainly of low salinity, but high salinity groundwater is evident beneath the lake bed. Porewater analyses reveal a salinity profile in a clay aquitard 50 m thick, beneath the lake bed, that has the characteristics of diffusion but is also influenced by mixing with (a) lakewaters infiltrating downwards , and (b) groundwaters rising upwards under pressure. Hydrostatic balance is apparently achieved at a depth of 10m below the lake bed; this coincides with the maximum porewater salinity of 40-42 000 mg/L total dissolved solids (TDS). Salt accumulates in lake-full periods and concentrates by evaporation of lake waters. A net loss of salt is evident in recessive phases of the lake. During drying and refilling episodes, the lake water surface becomes the water table and vice versa. Salt is concentrated in the capillary zone during dry periods and is also transmitted downwards by diffusion. In recessive phases there is infiltration of lake water which has a freshening effect on the top of the salinity profile, but also transmits some salt. The processes of salt accumulation and diffusion in the aquitard may have operated for much of the Quaternary. In the Lake George basin , five types of water are characterised: surface water in creeks and in the lake; groundwater in the catchment, and in sandy aquifers beneath the lake and bed; and porewater in the clay aquitard underlying the lake bed. Creek water and catchment groundwater is fresh to brackish and generally of the HCO3-Cl or CI-HCO3 type with Na and Mg as major cations. The lake water is alkaline, of varying salinity up to 45 000 mg/L TDS, and of the Cl-Na type. Varying ionic concentrations in these waters are the result of evaporative concentration and precipitation of carbonate minerals. Beneath the lake bed are saline aquifer groundwaters (up to 48000 mg/L TDS) and aquitard porewaters (up to 42000 mg/L TDS); these are Cl-Na waters with appreciable Mg. Sulphate is also retained in the groundwater which evolves chemically through interaction with the aquifer matrix. Hydrochemical evolutionary pathways are different for groundwaters and for surface waters. In surface waters (creek and lake), dolomite and calcite saturation is achieved early but these waters are undersaturated with gypsum. In the groundwaters (catchment and lake bed), saturation with dolomite and calcite is achieved early but equilibrium relationships are more complex. Shallow groundwaters, down to 15 m beneath the lake bed, show evidence of mixing with infiltrating lake waters, and this has retarded mineral precipitation. The deeper, saline ground waters are close to saturation with gypsum . Stable isotope data also indicate mixing down to 15m below the lake bed between evaporated lake waters infiltrating downwards and saline groundwaters under upwards pressure. Chlorine-36 determinations indicate that younger groundwaters at 10-50 m below the lake bed overlie ground waters at 100 m that are tens of thousands of years old.

Four benthic marine fossil commumtles are recognised in faunas of the Rhipidomella fortimuscula brachiopod Zone of late Visean (Early Carboniferous) age using multivariate (cluster) analysis of bulk samples extracted from available fossiliferous horizons. As a consequence of their occurrence over a wide geographic area, the communities are considered to be representative collections of in situ invertebrates (largely brachiopods). The number of species and genera in each community varies according to the favourability of water column and substrate conditions for habitation by such invertebrate filter-feeders. Elements of the Balanoconcha elliptica community were present in marine shelf waters with high suspended-sediment concentrations in the water column, such conditions excluded all but a few species well adapted to them. The Rhipidomella fortimuscula community was present in turbulent nearshore conditions, but could also tolerate calmer conditions below wave-base. The Tylothyris planimedia and Marginicintus reticulatus communities inhabited quiet-water conditions, one closer to shore than the other, but differ in the number and variety of species present. The Marginicintus reticulatus community is the most widespread and has the highest species diversity. Sampling by bulk collection allows the communities to be identified by the distribution and abundance of all species. Clusters formed by multivariate analysis identify the recurrent species associations or communities. Examination of the communities show that several species are numerically important in more than one community. It is suggested from this evidence that the communities do not contain mutually exclusive species associations, but are abstractions from a continuum . As such the communities intergrade and are distinguishable on the basis of their total faunal content. Several species comprise the most abundant forms in more than one community: Balanoconcha elliptica, Rhipidomella fortimuscula, Marginicintus reticulatus, and Tylothyris planimedia. The community assemblages are gradational (Whittaker community concept) rather than forming fixed associations inhabiting specific depth zones (Petersen community concept). Compared to the time averaged nature of fossil communities, surveys of modern benthic communities are an instantaneous view of biota and less likely to identify the long-term impact of periodic perturbations. Major periodic fluctuations in environmental parameters are more likely to be reflected over time in the fossil record where the populations of more than one generation are preserved. The inherently patchy nature of both fossil and modern benthic species populations is also a feature readily evident in th e fossil record, but more difficult to detect in modern surveys. Marine benthic communities of the Rhipidomella fortimuscula Zone provide an illustration of the cumulative effects of gradational faunal boundaries and the inherent patchiness of species populations.

Fresh to brackish groundwaters in the range of 250 to 2250 mglL occur in fractured bedrock aquifers beneath dryland salinity sites at Yass in the Southern Tablelands of New South Wales. The fractured bedrock in these catchments comprises marine, early Paleozoic slates, shales and sandstones in Dicks Creek and Williams Creek catchments, and porphyritic dacite and rhyodacite in Spring Creek catchment. The groundwaters are known to originate from recent meteoric waters. The waters represent various hydrochemical types, generated by chemical processes through water-rock interactions along their flow paths. The present chemical composition of major cations and anions in groundwaters from these catchments is derived from the following processes: 1. water-rock interaction in recharge zones where dissolution of minerals and oxidation processes occur, 2. ion-exchange and reverse ion exchange reactions with clay where it is present in fractures and veins in the bedrock, and 3. microbially mediated reactions with organic matter which produce very low redox potentials.