No abstract available

Describes the development of the late Silurian-early Devonian Jemalong Trough in the eastern Lachlan Fold Belt.

Geochronology is the vital fourth dimension for geological knowledge. It provides the temporal framework for understanding and modelling geological processes and rates of change. Incorporating geochronological 'observations and measurements' into interoperable geological data systems is thus a critical pursuit. - Although there are several resources for storing and accessing geochronological data, there is no standard format for exchanging such data among users. Current systems are a mixture of comma-delimited text files, Excel spreadsheets and PDFs that assume prior specialist knowledge and frequently force the user to laboriously - and potentially erroneously - extract the required data manually. - Geoscience Australia and partners are developing a standard data exchange format for geochronological data ('geochronML') within the broader framework of Observations and Measurements and GeoSciML that are an important facet of emerging international geoscience data format standards. - Geochronology analytical processes and resulting data present some challenging issues as a rock "age" is typically not a direct measurement, but rather the interpretation of a statistical amalgam of several measurements chosen with the aid of prior geological knowledge and analytical metadata. The level at which these data need to be exposed to a user varies greatly, even to the same user over the course of a project. GeochronML is also attempting to provide a generic pattern that will support as wide as range of radioisotopic systems as possible. This presentation will discuss developments at Geoscience Australia and the opportunities for collaboration.

In 2007, NTGS commenced work on a new project in the central Arunta Region, initially focused in the southwest of the Alcoota 1:250k mapsheet. This project incorporates work by NTGS in 2002 in the central northern 1:100k mapsheet (Woodgreen) of Alcoota (Haines and Scrimgeour 2007). The central Arunta is critical to furthering the development of an integrated framework of the Arunta Region, and builds on NTGS work since 2000 in the southwestern, northern and eastern Arunta. The project will add important information to the emerging picture of the evolution and tectonic context of the amalgamation of this complex terrane.

Over the last 20 years, it has become common practice to treat SIMS measurements of ²⁰⁷Pb/²⁰⁶Pb in zircon as unfractionated. Consequently, uncertainties associated with composite ²⁰⁷Pb/²⁰⁶Pb values are often limited only by population statistics of the weighted mean, and citation of 95% confidence limits of 1- (or less) on Meso- to Paleoarchean mean ages is increasingly commonplace. In such cases, the presence of undiagnosed SIMS instrumental mass fractionation of ²⁰⁷Pb/²⁰⁶Pb of similar magnitude (1-2-) could have serious ramifications for the accuracy of the measured age: in extreme cases, the 'true' ²⁰⁷Pb/²⁰⁶Pb may not even lie within the artificially narrow 95% confidence interval of the measured value. This possibility has important implications for high-precision zircon geochronology via SIMS, and the correlation of Precambrian events. Our previous work has characterized (via ID-TIMS) a Paleoarchean igneous zircon reference material ('OG1'). Its reference ²⁰⁷Pb/²⁰⁶Pb is 0.29907 ± 0.00011 (3465.4 ± 0.6 Ma) for natural (air-abraded) zircon, and 0.29939 ± 0.00012 (3467.1 ± 0.6 Ma) for zircon annealed and chemically abraded using the Mattinson technique. The corresponding reference ²⁰⁶Pb/²³⁸U ages are 3440.7 ± 3.2 Ma and 3463.3 ± 3.6 Ma respectively.

Continuously cored ODP Leg 189 sites document the marine sequences deposited before, during and after the Tasmanian (Australian-Antarctic) Gateway opened (~33.5 Ma) and deepened. The sites are all on continental crust: one west of Tasmania, three on South Tasman Rise (STR) and one on East Tasman Plateau (ETP). The Tasmanian `land bridge? linked Australia and Antarctica and incorporated parts of Tasmania and STR; one site lay in the gradually widening but restricted Australo-Antarctic Gulf (AAG) in the Indian Ocean, and the others in the more open proto-Pacific Ocean. The main four sites vary in sub-seafloor depth from 776 to 959 m, and their oldest sequence from lowest Upper Eocene (AAG) to Maastrichtian (ETP). The sites are broadly similar, with variations depending on tectono-sedimentary setting. Depositional rates seldom exceeded 4 cm/ky. Until the Oligocene, the region was near the Antarctic margin in very high palaeolatitudes, and dinocyst, diatom and magnetostratigraphic data provide most dating and marine environmental information. From the Late Cretaceous through Late Paleocene (95-55 Ma) left-lateral strike-slip motion moved the Tasmanian region northwest past Antarctica, and Tasman Basin rifting and seafloor spreading occurred in the east. Deltaic sequences filled depocentres with dark, restricted, paralic and marine mudstones (drilled on ETP, STR). At the Paleocene/Eocene boundary (55 Ma) Australia-Antarctic motion changed to north-south along the Tasman Fracture Zone west of STR, and Tasman Basin spreading ceased. South of eastern STR an oceanic basin opened. Fast spreading, beginning in the Middle Eocene, carried this region northward (~43 Ma). In the Early and Middle Eocene, deposition continued of dark, largely deltaic, and broadly similar shallow marine mudstones (thinnest on ETP). Proto-Pacific mudstones become more open marine with time, but AAG mudstones remained restricted. In the Late Eocene (37-33.5 Ma) the continental margins sagged, the water deepened, and some currents may have flowed through shallow seaways. Sedimentation rates declined as winnowing increased and hiatuses formed. On the AAG margin restricted shallow marine mudstone and sandstone were deposited. In the proto-Pacific, as the water deepened in the latest Eocene, marine mudstone gave way to winnowed marine glauconitic siltstone and sandstone. Rapid subsidence followed the final separation of STR and Antarctica. In the proto-Pacific, strong currents swept the shelves and opening straits, and an Early Oligocene hiatus was overlain by Oligocene open marine bathyal carbonates. The AAG margin was now less restricted, but calcareous mudstones had only gradual carbonate increases through into the lower Miocene. From the Oligocene on, calcareous nannofossils, planktonic foraminifers and magnetostratigraphic data provide most dating and marine environmental information. The Neogene sequences, which consist of bathyal chalk and oozes, with limited disconformities in parts of the Miocene, have proved ideal for detailed palaeo-oceanographic/climatic isotope studies - rare in the Southern Ocean.

Australia has been making major progress towards early deployment of carbon capture and storage from natural gas processing and power generation sources. This paper will review, from the perspective of a government agency, the current state of various Australian initiatives and the advances in technical knowledge up until the 2010 GHGT conference. In November 2008, the Offshore Petroleum and Greenhouse Gas Storage Bill 2006 was passed by the Australian Parliament and established a legal framework to allow interested parties to explore for and evaluate storage potential in offshore sedimentary basins that lie in Australian Commonwealth waters. As a result of this Act, Australia became the first country in the world, in March 2009, to open exploration acreage for storage of greenhouse gases under a system that closely mirrors the well-established Offshore Petroleum Acreage Release. The ten offshore areas offered for geological storage assessment are significantly larger than their offshore petroleum counterparts to account for, and fully contain, the expected migration pathways of the injected GHG substances. The co-incidence of the 2009 Global Financial Crisis may have reduced the number of prospective CCS projects that were reported to be in the 'pipe-line' and the paper examines the implications of this apparent outcome. The Carbon Storage Taskforce has brought together both Australian governments technical experts to build a detailed assessment of the perceived storage potential of Australia's sedimentary basins. This evaluation has been based on existing data, both on and offshore. A pre-competitive exploration programme has also been compiled to address the identified data gaps and to acquire, with state funding, critical geological data which will be made freely available to encourage industrial participation in the search for commercial storage sites.

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