This data package was preduced in response to a request by Rodney King from Teck Australia for a compilation of GA borehole datasets from the Isa Superbasin, in particular for gamma-ray data. The data set includes drill hole/section location information, and lithological, geochemical and gamma ray data. All data were extracted from GA databases.

The Neoproterozoic to Palaeozoic Thomson Orogen occupies a large portion of eastern Australia but is poorly known due to extensive cover. Currently, models for the tectonic evolution of the Thomson Orogen and its relationship to surrounding elements largely focus on the exposed areas. The long and complex structural and thermal history interpreted from these outcropping rocks raises many questions as to the age and origin of rocks in the vast undercover portion of the Thomson Orogen. Glimpses of the undercover Thomson Orogen are revealed in basement intersections of petroleum drill cores throughout central and south-western Queensland. These are dominated by low grade metasedimentary rocks (dominantly turbidites) with minor volcanic rocks and granites. New in-situ zircon analysis for U-Pb (SHRIMP) and Lu-Hf (Laser ablation multi-collector ICP-MS) isotopes are presented here and provide new temporal and provenance information for the rocks occurring beneath cover. Two distinct detrital zircon signatures are identified. A 'Pre-Gondwana' signature is identified in two drill holes on the north-western margin of the Thomson Orogen, adjacent to the North Australian Craton (GSQ Machattie 1, HPP Goleburra 1). These samples both have near-unimodal zircon age peaks at ~1180 Ma. -Hf (900-1300Ma) values from HPP Goleburra 1 display a range of -Hf(t) between 0 and 9 representing a moderately juvenile source. These sediments were possibly derived from the Musgrave Province in central Australia during the Cambrian Petermann Orogeny. Comparable detrital zircon age spectra from the Amadeus and Officer Basins suggests that the Thomson Orogen was connected and formed part of the greater Centralian Superbasin during this period. The second detrital zircon signature is identified extensively throughout the Thomson Orogen in basement drill cores (GSQ Eromanga 1, AAO Beryl 1, GSQ Maneroo 1, DIO Naryilco 1, DIO Betoota 1) and the outcropping Puddler Creek Formation and Les Jumelles Beds. This signature is remarkably consistent and characterised by a dominant age peak at ~570 Ma, a lesser population between ~1300-900 Ma and maximum depositional ages of ~495 Ma. This pattern is termed the 'Pacific Gondwana' detrital zircon signature and is widely recognised in eastern and central Australia and Antarctica. -Hf(500-700) data for Thomson Orogen rocks with this signature is highly variable with -Hf(t) values between -20 and 8 suggesting input from multiple source regions. Our isotopic work suggests connectivity between the Centralian Superbasin and the Thomson Orogen during and after the ~570-530 Ma, Petermann Orogeny. Parts of the uplifted Musgrave Province remained the dominant source of sediments until at least the late Cambrian when the Pacific Gondwana signature became dominant in the Thomson Orogen and central Australian basins.

The Walloon Coal Measures (WCM) in the Clarence-Moreton and the Surat basins in Qld and northern NSW contain up to approximately 600 m of mudstone, siltstone, sandstone and coal. Wide-spread exploration for coal seam gas (CSG) within both basins has led to concerns that the depressurisation associated with the resource development may impact on water resources in adjacent aquifers. In order to predict potential impacts, a detailed understanding of sedimentary basins hydrodynamics that integrates geology, hydrochemistry and environmental tracers is important. In this study, we show how different hydrochemical parameters and isotopic tracers (i.e. major ion chemistry, dissolved gas concentrations, 13C-DIC, 18O, 87Sr/86Sr, 3H, 14C, 2H and 13C of CH4) can help to improve the knowledge on groundwater recharge and flow patterns within the coal-bearing strata and their connectivity with over- or underlying formations. Dissolved methane concentrations in groundwaters of the WCM in the Clarence-Moreton Basin range from below the reporting limit (10 µg/L) to approximately 50 mg/L, and samples collected from nested bore sites show that there is also a high degree of vertical variability. Other parameters such as groundwater age measurements collected along distinct flow paths are also highly variable. In contrast, 87Sr/86Sr isotope ratios of WCM groundwaters are very uniform and distinct from groundwaters contained in other sedimentary bedrock units, suggesting that 87Sr/86Sr ratios may be a suitable tracer to study hydraulic connectivity of the Walloon Coal Measures with over- or underlying aquifers, although more studies on the systematic are required. Overall, the complexity of recharge processes, aquifer connectivity and within-formation variability confirms that a single tracer that cannot provide all information necessary to understand aquifer connectivity in these sedimentary basins, but that a multi-tracer approach is required.

This presentation will provide an overview of geological storage projects and research in Australia.

Abstract: The onshore Georgina Basin in northern Australia is potentially prospective for unconventional hydrocarbons, however, like many frontier basins it is under-explored. A well-connected hydraulic fracture network has been shown to be essential for the extraction of resources from the tight reservoirs that categorise unconventional plays, as they allow for economic flows of fluid from the reservoir to the well. One of the fundamental scientific questions regarding hydraulic stimulation within the sub-surface of sedimentary basins is the degree to which local and regional tectonic stresses act as a primary control on fracture propagation. As such, an understanding of present-day stresses has become increasingly important to modern petroleum exploration and production, particularly when considering unconventional hydrocarbon reservoirs. This study characterises the regional stress regime in the Georgina Basin using existing well data. Wellbore geophysical logs, including electrical resistivity image logs, and well tests from 31 petroleum and stratigraphic wells have been used to derive stress magnitudes and constrain horizontal stress orientations. Borehole failure features interpreted from wellbore image and caliper logs yield a maximum horizontal stress orientation of 044°N. Integration of density log data results in a vertical stress gradient of 24.6 MPa km-1. Leak-off and mini-fracture tests suggest that this is the minimum principle stress, as leak-off values are generally shown to be at or above the magnitude of vertical stress. The maximum horizontal stress gradient is calculated to be in the range of 34.0-53.9 MPa km-1. As such, a compressional stress regime favouring reverse/reverse'strike-slip faulting is interpreted for the Georgina Basin.

Deep basement cores from petroleum and stratigraphic drill holes through central and southwest Queensland show that the subsurface Thomson Orogen is dominated by monotonous metasedimentary units but also includes scattered felsic volcanic rocks and more abundant (locally batholithic-scale) intrusions. These igneous rocks and small granitoid exposures along the Eulo Ridge provide means of probing the deeper crustal composition and the geological evolution of this vast area that is mostly covered by deep sedimentary basins.

The Upper Burdekin Chloride Mass Balance Recharge web service depicts the recharge rates have been estimated at borehole locations in the Nulla and McBride basalt provinces. Using rainfall rates, rainfall chemistry and groundwater chemistry, the recharge rates have been estimated through the Chloride Mass Balance approach.

Planktic and larger benthic foraminiferids have been studied in thin section from a suite of dredge samples of two sites on the Marion Plateau, offshore Queensland. The two sites gave different results. (1) The northern site sampled an Early to Middle Miocene carbonate platform, with shallow-water foraminiferal assemblages. This limestone has solution cavities (developed during periods of subaerial exposure) infilled with Late Miocene shallow-water planktic foraminiferid-bearing sediments. The rock is cross-cut by several generations of mud-filled borings. Some of the fill in these borings could be biostratigraphically dated, with ages ranging from Pliocene to Pleistocene. (2) At the southern site, a Late Miocene carbonate platform was sampled; the only sample recovered was a limestone slab consisting of a late Miocene rhodolith-bearing floatstone with a marine hardground overlain by a condensed section of phosphatic wackestone of Pliocene age. A series of mounds is present down the slope from the Late Miocene platform sampling site; these also were sampled and were found to be of probable Pliocene and probable Pleistocene age (Zones N.18 and N.22). Water depths for the deposition of the platform phase were shallow, probably less than 50 m, as testified by the presence at the northern site of large benthic foraminiferids, Halimeda , hermatypic corals, and nodular coralline algae. The cavity-fill sediments, probably typical of the overlying sediments, have good planktic foraminiferal faunas, but also include some shallow-water faunal components (Amphistegina) and reworked older faunas (Lepidocyclina). The infilled borings tend to be almost totally composed of planktic foraminiferids, as do some discrete samples. This faunal evidence indicates that for the northern platform no deposition took place during much of the Middle Miocene and early Late Miocene, probably due to a long period of subaerial exposure. During the Late Miocene, the northern platform slope was flooded and subsided to its present depth by the Pleistocene. The southern platform was built during the Late Miocene and subsided to its present depth in the Pliocene. Samples from the mounds contain shallow-water assemblages of two ages: one may be of similar Pliocene age as found on the platform sites, and another of probable Pleistocene age. The presence of hermatypic corals, Halimeda, and larger benthic foraminiferids suggest warm surface water temperatures since the Early Miocene.

The Queensland Trough is a 155°-trending bathymetric deep, located just seaward of the Great Barrier Reef of northeast Australia. The trough reaches a maximum depth of 2800 m, separating the continental shelf and the submerged Queensland Plateau. It is underlain by extended continental crust. This preliminary interpretation of the troughs deep structure uses 3700 km of 1970s vintage seismic data, supplemented by gravity and magnetic data from the same surveys. The main seismic profile grid has a spacing of approximately 50 km. However, another survey shot in a zigzag pattern provides line spacing locally as close as a few kilometers. Acoustic basement, characterized by a chaotic and indistinct seismic signature with rare, discontinuous steeply dipping reflections, is overlain by two main acousto-stratigraphic megasequences within the trough: (1) The post-rift section comprises flat-lying , continuous reflections and extends up to two seconds two-way travel time (TWT) below the water bottom. (2) The syn-rift section consists of moderately dipping semi-continuous reflections, separated by zones of chaotic reflections and diffractions. The reflection separating the syn- and post-rift packages is quite distinct, characterized by angular discordances and truncated reflections. No wells have penetrated the syn-rift package. Seismic profiles in all orientations reveal tilted basement fault blocks . Many bounding faults are clearly listric. Half-graben form a series of syn-rift depocenters with up to 5 km of syn-rift fill. Syn-rift depocenters appear to be elongate along the axis of the trough, suggesting rift-parallel bounding faults and orthogonal extension. However, no structures parallel or perpendicular to the trough axis have been recognized. Most of the syn-rift depocenters are composed of two or more smaller "deeps". Two rifting models provide alternative syn-rift structural interpretations: (1) Curvilinear faults, based on a model derived from the East African Rift where the tectonic transport direction has been shown to be oblique to the rift axis, define a series of half-graben. Accommodation zones and half-graben polarity switches are identified from profile and plan-view geometries. (2) Nearly rectilinear 110°_ and 020o -striking faults, based on orthogonal extension models, predominate. However, both of these trends are oblique to the rift axis contrary to predicted geometries. "Transfer faults" provide a structural basis for the apparent compartmentalization the syn-rift isopach cells into the "deeps". The data are insufficient to unequivocally support either model, although the orthogonal extension fault geometry better explains the distribution of the depocenters. Both interpretations, combined with limited basement dip information suggest that the structure underlying the Queensland Trough is the product of oblique rifting. Extension is aligned obliquely to the trough at 110°, rather than perpendicular to the rift elongation at 065°. The proposed kinematics suggest that formation of the trough pre-dates either the Coral or Tasman Sea taphrogenesis.