This service provides access to hydrochemistry data (groundwater and surface water analyses) obtained from water samples collected from Australian water bores or field sites.

This report is published in two volumes; Volume I: Bowen-Surat and Cooper-Eromanga Basins, Volume II: Gippsland, Bass, Otway, Stansbury, McArthur, Amadeus, Adavale, Galilee and Drummond Basins. Following the basin-by-basin analysis of geochemical characteristics of eastern Australia's oils, a selection of oils that best represented the major families of each region were selected. These oils were statistically analysed using a subset of geochemical (OilMod) parameters derived from GC, GC-MS and carbon isotopic analyses. This exercise was intended to display the variability in oil compositions across the whole of the eastern part of the continent. The chemical classification of oils follows closely upon, and verifies the analysis based on, palaeogeography and the supersystem concepts.

Earth is the only terrestrial planet in the solar system with continents, and hence understanding their evolution is vital to unravelling what makes Earth special – our liquid oceans, oxygenated atmosphere, and ultimately, life. The continental crust is also host to all our mineable mineral deposits, and hence it has played a key role in the establishment of human civilisation. This link between the crust and human development will be even more prominent through the need for critical metals, as our society transitions toward green technologies. In this talk, we will discuss the link between the time-space evolution of the continental crust and the location of major mineral systems. By using isotopic data from micron-scale zircon crystals, we can map the crustal architectures that control the large-scale localisation of numerous mineral provinces. This work demonstrates the intimate link between the evolution of the continents, the understanding of mineral systems, and ultimately our continued evolution as an industrialised society.

Aspects of the tectonic history of Paleo- to Mesoproterozoic Australia are recorded by metasedimentary basins in the Mt Isa, Etheridge Provinces, and Coen Inlier in northern Australia and in the Curnamona Province of southern Australia. These deformed and metamorphosed basins are interpreted to have been deposited in a tectonically-linked system based on similarities in depositional ages and stratigraphy (Giles at al 2002). Neodymium isotope compositions of sediments and felsic volcanics, when combined with U-Pb geochronology, are independent data that are important tools for inferring tectonic setting, palaeogeography and sediment provenance in deformed and metamorphosed terrains.

As recognised by the Academy of Science's UNCOVER group in their `Searching the Deep Earth' document, a goal for geoscientific advancement in Australia is a `holistic understanding of our continent so that we might better predict the location of large-scale mineral systems. This view included the investigation of Australia's lithospheric architecture to establish a whole-of-lithosphere architectural framework as a priority. An important component of the Earth's lithosphere is the crust, most of which is clearly inaccessible. Just as the study of basaltic rocks has provided insight into the earth's mantle, granites provide a (not always wholly transparent) window into the middle and lower continental crust. Studies of these rocks are enhanced by isotopic tracers, such as Samarium-Neodymium, which can affectively `see through' the granite to provide constraints on crustal formation, and enable us to map the Australian crust. This approach and the application of Samarium-Neodymium isotope data were used by Geoscience Australia for the Archean Yilgarn Craton of Western Australia. Studies in that region showed that regional scale Samarium-Neodymium signatures in felsic igneous rocks (tonalite to granite and volcanic equivalents) were not only able to map crustal architecture but that this architecture had unexpected correlations with mineralisation. The successful results in the Yilgarn Craton, coupled with the UNCOVER focus, warranted that this approach be extended to the whole of the continent to test its general applicability for crustal mapping and predicting mineralisation. A database of Sm-Nd isotopic data, and associated metadata, for >2650 samples of Australian rocks was compiled from published and unpublished sources. This included location, unit, geochronology and bibliographic data and metadata for all data points; this dataset is available for download at www.ga.gov.au. Data were compiled for a range of lithologies, including felsic and mafic igneous rocks, sedimentary rocks, as well as some mineral data. Just over 1630 of these data points were from felsic igneous rocks which had reliable locational details and a reasonable estimated or known magmatic age. A comparison of the magmatic ages from these samples with compilations of Australian igneous rock ages showed a generally good agreement confirming the representative nature of the compiled Nd data set.

Intrusive and extrusive, predominantly felsic, magmatism of Carboniferous to Permian age occurs throughout the north Queensland region (Figure kennedy), and comprises the most widespread and voluminous magmatic event in the region. The great bulk of the exposed KIA is concentrated in the Townsville-Cairns-Cooktown-Georgetown-Charters Towers-Burdekin Falls regions (Figure Kennedy)-within the early-mid-Palaeozoic Hodgkinson and Broken River Provinces, the Etheridge Province and associated Proterozoic provinces, and in the northern part of the Thomson Orogen including the Greenvale, Charters Towers, and Barnard Provinces, and the northern Drummond Basin. The boundary between the northern Drummond Basin and Connors (nNEO) Subprovince is taken to be the Millaroo Fault Zone (MFZ). Geophysical data (and limited geochronology) show that Carboniferous-Permian granites also form a westerly trending belt-the Townsville-Mornington Island Belt (TMIB; originally Townsville-Mornington Island Igneous Belt), which extends under cover from north of Mount Surprise, at least as far as Mornington Island in the Gulf of Carpentaria, transecting regional trends (Wellman, 1992, 1995; Wellman et al., 1994). There is also recent geochronological evidence for KIA magmatism in the environs of the Millungera Basin (Neumann & Kositcin, 2011). Outcrop is discontinuous in the belt extending northwards from Cairns up Cape York Peninsula, to the islands of Torres Strait (and beyond) but geophysical evidence implies there is more extensive magmatism under cover.

Vertical geochemical profiling of the marine Toolebuc Formation, Eromanga Basin - implications for shale gas/oil potential The regionally extensive, marine, mid-Cretaceous (Albian) Toolebuc Formation, Eromanga Basin hosts one of Australia's most prolific potential source rocks. However, its general low thermal maturity precludes pervasive petroleum generation, although regions of high heat flow and/or deeper burial may make it attractive for unconventional (shale gas and shale oil) hydrocarbon exploration. Previous studies have provided a good understanding of the geographic distribution of the marine organic matter in the Toolebuc Formation where total organic carbon (TOC) contents range to over 20% with approx. half being of labile carbon and convertible to gas and oil. This study focuses on the vertical profiling, at the decimetre to metre scale, of the organic and inorganic geochemical fingerprints within the Toolebuc Formation with a view to quantify fluctuations in the depositional environment and mode of preservation of the organic matter and how these factors influence hydrocarbon generation thresholds. The Toolebuc Formation from three wells, Julia Creek-2 and Wallimbulla-2 and -3, was sampled over an interval from 172 to 360m depth. The total core length was 27m from which 60 samples were selected. Cores from the underlying Wallumbilla Formation (11 samples over 13m) and the overlying Allaru Mudstone (3 samples) completed the sample set. Bulk geochemical analyses included %TOC, %carbonate, %total S, -15N kerogen, -13C kerogen, -13C carbonate, -18O carbonate, and major, minor and tracer elements and quantitative mineralogy. More detailed organic geochemical analyses involved molecular fossils (saturated and aromatic hydrocarbons, and metalloporphyrins), compound specific carbon isotopes of n-alkanes, pyrolysis-gas chromatography and compositional kinetics. etc.

The carbon and hydrogen isotopic data of natural gases provide a crucial tool to interpret the origin, occurrence and inter-relationships of natural gases. The CF-GC-IRMS is a convenient system to separate gas mixture and obtain continuous, on-line isotopic data of individual compounds. With CF-GC-IRMS system, the abundance of target components is crucial. For an accurate result, there should be enough target compound going through the furnace to be measured as CO2 using isotopic ratio mass spectrometry. For carbon isotopes, a m/z 44 response below 0.3 V (or over 7V) is regarded as unreliable. For high abundant compounds, there is no difficulty in attaining a voltage over 0.3V with a normal injection of under 100ul with adjusted split flow. However, the acquisition for the low concentration component is problematic since "normal" injection would not produce a strong enough signal. In this presentation, we demonstrated the techniques used to obtain low concentration components occurring in the Australian natural gases and how we apply the results in gas comparison studies. Cryogenics (liquid nitrogen trap) is applied to trap and concentrate low amount of compounds other than methane (C1), including CO2, C2 and above. With this method, extreme low concentration of C2 from very dry gases was obtained with large volume injection of 10ml. Back-flash is used together with cryogenics. For analyses for only C4 and C5 compounds, cryogenics was not needed, since they focus at the front of the column at 40oC and elute from the column under oven temperature programming as single peaks. Neo-pentane (neo-C5) is generally the least abundant wet gas component. Its concentration is enhanced in the gases which are biodegraded, wherein the other gas components have been selectively removed by microbial activity. Neo-pentane is extremely resistant to biodegradation and shows no isotopic alteration even in severely biodegraded gas. In such cases, neo-C5 is the only gas component that can be confidently used in gas-gas correlation. Neo-pentane is an example where we employ injection of a large volume (e.g. to 40ml for hydrogen isotopes), combining a back-flashing technique for compounds eluting before C4 (inclusive) and C5 compounds. The neo-C5 elutes between nC4 and i-C5. Under the current GC conditions, there is a time "window" of less than 40 seconds to capture neo-C5. A manual operation to set back-flash to straight flow to allow capture neo-C5 just after n-C4 elutes and then back to back-flush to eliminate interference of C5's compounds. Mass balance estimation indicates that there is no loss of neo-C5 during the large volume injection and repeatability is excellent.

Inland sulfidic soils have recently formed throughout wetlands of the Murray River floodplain associated with increased salinity and river regulation (Lamontagne et al., 2006). Sulfides have the potential to cause widespread environmental degradation both within sulfidic soils and down stream depending on the amount of carbonate available to neutralise acidity (Dent, 1986). Sulfate reduction is facilitated by organic carbon decomposition, however, little is known about the sources of sedimentary organic carbon and carbonate or the process of sulfide accumulation within inland sulfidic wetlands. This investigation uses stable isotopes from organic carbon (13C and 15N), inorganic sulfur (34S) and carbonate (13C and 18O) to elucidate the sources and cycling of sulfur and carbon within sulfidic soils of the Loveday Disposal Basin.

S-type granites crop out extensively (>2500 km2) in the central and eastern parts of the Hodgkinson Province, north Queensland, Australia, forming two NW to NNW trending belts, outboard of an extensive belt of (mainly late Carboniferous) I-type granites. The S-type granites, which comprise muscovite-biotite syenogranite and monzogranite, and rare granodiorite, have been subdivided in two major supersuites: the Whypalla and Cooktown Supersuites; and a number of minor suites - including the highly differentiated Wangetti and Mount Alto Suites. The S-type granites intrude a very extensive, siliciclastic flysch sequence (late Silurian? to earliest Carboniferous) that is isotopically evolved (e.g., Nd mostly -12.0 to -15.0 at 270 Ma), and generally too mature (too CaO poor) to produce S-type granites. Isotopic and chemical modeling show that although magma-mixing is permissible, the levels permissible (<ca 20-25% basaltic input), are not large enough to explain the signature of the S-type granite. Either more complex mixing models, e.g., crustal melts with a history of mixing, or the presence of more suitable metasedimentary source rocks at depth, is required. The latter is consistent with the (uncommon) presence within the eastern parts of the Hodgkinson Province of metasediments with isotopic signatures similar to the S-type granites. These provide strong support for more extensive such rocks at depth, consistent with other local geology and accretionary tectonic models for the region.