The Archean Yilgarn Craton of Western Australia, is not only one of the largest extant fragments of Archean crust in the world, but is also one of the most richly-mineralised regions in the world. Understanding the evolution of the craton is important, therefore, for constraining Archean geodynamics, and the influence of such on Archean mineral systems. The Yilgarn Craton is dominated by felsic intrusive rocks - over 70% of the rock types. As such these rocks hold a significant part of the key to understanding the four-dimensional evolution of the craton, providing constraints on the nature and timing of crustal growth, the role of the mantle, and also the timing of important switches in crustal growth geodynamics. The granites also provide constraints on the nature and age of the crustal domains within the craton. Importantly, this crustal pre-history appears to have exerted a significant, but poorly understood, spatial control on the distribution of mineral systems, such as gold, komatiite-associated nickel sulphide and volcanic-hosted massive sulphide (VHMS) base metal systems

Lord Howe Island is a small, mid-ocean volcanic and carbonate island in the southwestern Pacific Ocean. Skeletal carbonate eolianite and beach calcarenite on the island are divisible into two formations based on lithostratigraphy. The Searles Point Formation comprises eolianite units bounded by clay-rich paleosols. Pore-filling sparite and microsparite are the dominant cements in these eolianite units, and recrystallised grains are common. Outcrops exhibit karst features such as dolines, caves and subaerially exposed relict speleothems. The Neds Beach Formation overlies the Searles Point Formation and consists of dune and beach units bounded by weakly developed fossil soil horizons. These younger deposits are characterised by grain-contact and meniscus cements, with patchy pore-filling micrite and mirosparite. The calcarenite comprises several disparate successions that contain a record of up to 7 discrete phases of deposition. A chronology is constructed based on U/Th ages of speleothems and corals, TL ages of dune and paleosols, AMS 14C and amino acid racemization (AAR) dating of land snails and AAR whole-rock dating of eolianite. These data indicate dune units and paleosols of the Searles Point Formation were emplaced during oxygen isotope stage (OIS) 7 and earlier in the Middle Pleistocene. Beach units of the Neds Beach Formation were deposited during OIS 5e while dune units were deposited during two major phases, the first coeval with or shortly after the beach units, the second later during OIS 5 (e.g. OIS 5a) when the older dune and beach units were buried. Large-scale exposures and morphostratigraphical features indicate much of the carbonate was emplaced as transverse and climbing dunes, with the sediment source located seaward of and several metres below the present shoreline. The lateral extent and thickness of the eolianite deposits contrast markedly with the relatively small modern dunes.

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.

Initial lead isotope ratios from Archean volcanic-hosted massive sulfide (VHMS) and lode gold deposits and neodymium isotope model ages from igneous rocks from the geological provinces that host these deposits identify systematic spatial and temporal patterns, both within and between the provinces. The Abitibi-Wawa Subprovince of the Superior Province is characterized by highly juvenile lead and neodymium. Most other Archean provinces, however, are characterized by more evolved isotopes, although domains within them can be characterized by juvenile isotope ratios. Metal endowment (measured as the quantity of metal contained in geological resources per unit surface area) of VHMS and komatiite-associated nickel sulfide (KANS) deposits is related to the isotopic character, and therefore the tectonic history, of provinces that host these deposits. Provinces with extensive juvenile crust have significantly higher endowment of VHMS deposits, possibly as a consequence of higher heat flow and extension-related faults. Provinces with evolved crust have higher endowment of KANS deposits, possibly because such crust provided either a source of sulfur or a stable substrate for komatiite emplacement. In any case, initial radiogenic isotope ratios can be useful in predicting the endowment of Archean terranes for VHMS and KANS deposits. Limited data suggest similar relationships may hold in younger terranes.

Paleoarchean rocks of the tonalite-trondhjemite-granodiorite (TTG) series require a basaltic source region more enriched in K, LILE, Th and LREE than the low-K tholeiites typical of Archean supracrustal sequences. Most TTG of the Pilbara Craton, in northwestern Australia, formed between 3.5 and 3.42 Ga through infracrustal melting of a source older than 3.5 Ga. Basaltic to andesitic rocks of the 3.51 Ga Coucal Formation, at the base of the Pilbara Supergroup, are amongst the only well-preserved remnants of pre-3.5 Ga supracrustal material on Earth, and may have formed a large proportion of pre-3.5 Ga Pilbara crust. These rocks are significantly enriched in K, LILE, Th and LREE compared to post-3.5 Ga Paleoarchean basalts and andesites, and form a compositionally suitable source for TTG. Enrichment in these basalts was not the result of crustal assimilation but was inherited from a mantle source that was less depleted than modern MORBsource and was enriched in recycled crustal components.We suggest that the formation of Paleoarchean TTG and of their voluminous mafic source regions reflects both a primitive stage in the thermal and compositional evolution of the mantle and a significant prehistory of crustal recycling.

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.

The Victoria and Birrindudu Basins of the Victoria River region, NW Northern Territory, represent a pair of stacked unmetamorphosed Palaeoproterozoic to Neoproterozoic basins unconformably overlying low-grade metamorphic basement. SHRIMP U-Pb analysis of detrital zircons provide a basis for lithostratigraphic correlations with other Proterozoic Basins across northern Australia. The Palaeoproterozoic Stirling Sandstone (basal Limbunya Group) is tentatively correlated with the Mount Charles Formation in the Tanami region. The Jasper Gorge Sandstone (basal Auvergne Group) correlates with basal units of the lower Cryogenian Supersequence 1 of the Centralian Superbasin (Heavitree Quartzite and its correlatives). A third correlation, previously proposed elsewhere and further explored here, suggests that the Duerdin Group may correlate with the upper Cryogenian ca. 635 Ma 'Marinoan' glacigenic units of Supersequence 3 of Centralian Superbasin. In particular, the Cryogenian pre-glacigenic Black Point Sandstone Member (basal Duerdin Group) is dominated by detrital zircons with age components characteristic of the Musgrave Complex, implying significant exhumation and erosion of the Musgrave Complex occurred, at least partially, prior to the end of the Cryogenian (<ca. 635 Ma) far earlier than generally thought. The latter two correlations suggest that the Victoria Basin in the Victoria River region represents yet another relic component of the extensive former Centralian Superbasin, at least during Cryogenian time. Sm-Nd whole rock determinations overwhelmingly, and unsurprisingly, are consistent with clastic derivation from the evolved North Australian Craton and, for the Black Point Sandstone Member, from the Musgrave Complex. A relatively juvenile signature ('Ndt ' +1) is observed coincident with aerial volcanism within the Birrindudu Basin at ca. 1640 Ma as has been recently noted in other Australian Palaeoproterozoic terrains.

Throughout New Zealand, the Torlesse Supergroup forms an extensive Permian to Cretaceous accretionary wedge of rather monotonous, sandstone-dominated turbidites. In contrast to contemporaneous rocks in neighbouring terranes within the accretionary wedge, the turbidites have less intermediate-volcaniclastic compositions, and show more quartzose, continent-derived, plutonic provenances. Petrographic, geochemical, isotopic and detrital mineral age characteristics all indicate that they did not originate at the contemporary Gondwanaland margin in New Zealand, but rather, constitute a suspect terrane (Torlesse Terrane), having sediment sources elsewhere along the margin. This latter subject has been controversial, with sediment sources suggested in Antarctica, southern South America and northeast Australia, but detailed Torlesse detrital mineral (zircon and mica) age data and bulk rock Sr-isotope patterns can be best matched for the most part with Carboniferous, Permian and Triassic sources in the New England Orogen, and the remainder with Cambrian and Ordovician sources in its hinterland.

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.

A major concern for regulators and the public with geological storage of CO2 is the potential for the migration of CO2 via a leaky fault or well into potable groundwater supplies. Given sufficient CO2, an immediate effect on groundwater would be a decrease in pH which could lead to accelerated weathering, an increase in alkalinity, release of major and minor ions and heavy metals (particularly Pd, Ni and Cr) as well as CO2 mobilisation of trace organic contaminants. These scenarios potentially occur in a high CO2 leakage event, therefore detection of a small leak, although barely perceptible, could provide an important early warning for a subsequent and more substantial impact. Different approaches are required for the detection and quantification of these low level leaks and are the subject of this paper. A 3 year groundwater survey was recently completed in the Surat Basin, which provided comprehensive water and isotopic analysis of groundwaters together with their exsolved gases. The gases were analysed for composition, -13CCO2, -13CCH4 and -2HCH4. Methane is prevalent in the major Surat Basin aquifers (e.g. Mooga, Gubberamunda and Hutton sandstones) and is invariably associated with a bacterial (methanogenic) carbonate reduction source, evident from its isotopic signature ('13CCH4 ~ -70', '2HCH4 ~ -220'). In addition to methane and low levels of CO2, trace ethane is common. Two neighbouring wells, however, were quite different to the other 85 wells surveyed. Their exsolved gases contained comparatively high ethane, but also C1-C6 hydrocarbons in addition to methane. Methane isotope systematics were significantly different from other groundwater wells completed in the same formation. The -13C of the CO2 was similar to the surrounding groundwater wells, but the relative proportion of CO2 in the gas was significantly higher. Combined, these characteristics are consistent with hydrocarbon biodegradation. There was little difference in the groundwater chemistry for these wells compared to the regional baseline. The study provides a useful analogue study for detection, at various scales, of a leaky well associated with a geological storage site. Compositional and isotopic analysis of exsolved gases from groundwater samples could be used to demonstrate non-equilibrium conditions and intrusion of exogenic CO2. Abstract for the 2013 International Association of Hydrologist Congress, Perth