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.

Metallogenic, geologic and isotopic data indicate secular changes in the character of VHMS deposits relate to changes in tectonic processes, tectonic cycles, and changes in the hydrosphere and atmosphere. The distribution of these deposits is episodic, with peaks at 2740-2680 Ma, 1910-1840 Ma, 510-460 Ma and 370-355 Ma that correspond to the assembly of Kenorland, Nuna, Gondwana and Pangea. Quiescent periods of VHMS formation correspond to periods of supercontinent stability. Large ranges in source 238U/204Pb that characterize VHMS deposits in the Archean and Proterozoic indicate early (Hadean to Paleoarchean) differentiation. A progressive decrease in - variability suggests homogenisation with time of these differentiated sources. Secular increases in the amount of lead and decreases in 100Zn/(Zn+Pb) relate to an increase in felsic-dominated sequences as hosts to deposits and an absolute increase in the abundance of lead in the crust with time. The increase in sulfate minerals in VHMS deposits from virtually absent in the Meso- to Neoarchean to relatively common in the Phanerozoic relates to oxidation of the hydrosphere. Total sulfur in the oceans increased, resulting in an increasingly important contribution of seawater sulfur to VHMS ore fluids with time. Most sulfur in Archean to Paleoproterozoic deposits was derived by leaching rocks below deposits, with little contribution from seawater, resulting in uniform, near-zero-permil values of 34Ssulfide. In contrast the more variable values of younger deposits reflect the increasing importance of seawater sulfur. Unlike Meso- to Neoarchean deposits, Paleoarchean deposits contain abundant barite, which is inferred to have been derived from photolytic decomposition of atmospheric SO2 and does not reflect overall oxidised oceans. Archean and Proterozoic seawater was more salty than Phanerozoic, particularly upper Phanerozoic, seawater. VHMS fluids ore fluids reflect this, also being saltier in Precambrian deposits.

The New England Orogen contains a geological record dominated by subduction-related rocks, indicating that the orogen has been part of, or adjacent to, convergent plate margins of eastern Gondwanaland from at least the Cambrian until the end of the Early Cretaceous (~95 Ma). In the late Devonian, the orogen records the change from an island arc setting to an Andean-style convergent continental plate margin (e.g., Flood & Aitchison 1992; Skilbeck and Cawood, 1994). The rock record prior to the Middle Devonian is fragmentary, but the Late Devonian to Carboniferous components of the continental margin magmatic arc, forearc basin and accretionary wedge system are well preserved in the New England Orogen, with the Lachlan Orogen, Thomson Orogen and Drummond Basin to the west being in a backarc setting at this time. This system ended in the Late Carboniferous, with the subduction zone stepping to the east (Cawood, 1984). Nevertheless, until at least the Early Cretaceous, the Australian component of the continental margin of East Gondwanaland faced the Proto-Pacific (Panthalassan) Ocean, and has been interpreted to form part of a subduction-related convergent plate margin (e.g. Powell 1984; Cawood 2005; Glen 2005). Here, we examine aspects of the southern New England Orogen from the Cambrian to the Early Permian to further document the nature of the convergent plate margin over this period of time. We are interested especially in the Tamworth Belt, where the changeover is recorded from the Cambrian-Late Devonian island arc setting, to the development of the Devonian-Carboniferous continental margin in a convergent plate setting, with its well developed forearc basin and accretionary wedge. The island arc component is referred to as the Gamilaroi Terrane by Aitchison and Flood (1995) and Offler and Gamble (2002).

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.

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.

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.

Natural gas is Australia's third largest energy resource after coal and uranium but despite this economic importance, the gas origin is not always recognized. To address this, isotope and geochemistry data have been collated on 850 natural gases from all of Australia's major gas provinces with proposed source ages spanning the earliest Paleozoic to the Cenozoic. Unaltered natural gases have a thermogenic origin ('13C methane ranges between -49 and -27'; 'D methane ranges between -290 and -125'). Microbially altered natural gases were identified primarily on the basis of 13C and D enrichments in propane and/or 13C depletion in methane and/or 13C enrichment in CO2. The carbon isotopic composition of the gas source has been estimated using '13C iso-butane as a surrogate for '13C kerogen while for gases where biodegradation is moderate to severe, '13C neo-pentane provides an alternative measure. The '13C kerogen of gas source rocks range from -47 to -22' with the older Paleozoic sources and marine kerogen amongst the most depleted in 13C. The '13C CO2 also provides an insight into crustal- and mantle-derived components while '15N N2 (-6.0 to 2.3' for N2 up to 47 %) distinguish between organic and inorganic (groundwater) inputs. This dataset provides a better understanding on the source and preservation history of Australian gas accumulations with direct implications on improving exploration success.

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.

In this paper, we present a high resolution study focussed mainly on the Gorgon field and associated Rankin Trend gas fields, Carnarvon Basin, Australia (Figure 1). These gas fields are characterized by numerous stacked reservoirs with varying CO2 contents and provide a relevant natural laboratory for characterizing CO2 migration, dissolution and reaction by looking at chemical characteristics of the different reservoirs (Figure 2). The data we present reveal interesting trends for CO2 mol% and -13C both spatially and with each other as observed by Edwards et al. (2007). Our interpretation of the data suggests that mineral carbonation in certain fields can be significant and relatively rapid. The Gorgon and Rankin Trend fields natural gases may therefore be a unique natural laboratory, which give further insights into the rates and extent of carbonate mineral sequestration as applied to carbon storage operations.

Database containing analytical data and interpretations from the Geoscience Geoscience (GA) geochronology program. Includes some legacy methods and externally sourced data. A collection of analytical data to support geochronology data or ages used in other reporting and publications.