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  • Poster prepared for International Association of Hydrogeologists Congress 2013 The Broken Hill Managed Aquifer Recharge (BHMAR) project has successfully mapped a multi-layered sequence of aquitards and aquifers, as well potential groundwater resource and managed aquifer recharge (MAR) targets, in the top 100m of the Darling Floodplain. Near-surface aquitards overlying the Pliocene target aquifers (fluvial Calivil Formation (CFm) and marine Loxton-Parilla Sands (LPS)), were identified initially as variably conductive layers in airborne electromagnetic (AEM) data, and validated by drilling and complementary borehole geophysical, textural, hydrogeological and hydrochemical studies. The stratigraphic unit underlying the Pliocene aquifers is the Miocene upper Renmark Group (uRG). Drilling and AEM data have confirmed this unit is present throughout the study area, deposited predominantly as thick muds. Facies and biofacies analysis suggests these muds were deposited on a low relief sedimentary plain with a high water table and numerous permanent water bodies, with relatively minor sand bodies deposited in narrow anastomosing fixed channel streams. Groundwater in the upper uRG is saline, and muddy sediments form a strongly conductive layer beneath the Pliocene aquifers. This is a much harder geophysical target than the upper confining aquitards, as the target lies at depths of 80-120m, which is near the depth resolution of the AEM system. Furthermore, there is little conductivity contrast between the Pliocene and uRG sediments except in areas where there is fresh groundwater in the former. Hydrochemical and hydrodynamic data shows that there is limited hydrological connection between the uRG and less saline Pliocene aquifers, except where the Pliocene is underlain by uRG channel sands. These channels are much narrower (10s to ~100m) and thinner (1 to 10m) compared with palaeochannels in the overlying CFm. Where the channels are connected, there can be a distinct salinity gradient from the Pliocene into the uRG sands, indicating localised mixing. Given the potential for up-coning of saline groundwater in these instances, a number of sites (e.g. Menindee Common), have been assessed as unsuitable for MAR. Overall, the uRG muds act as a good lower confining aquitard to the Pliocene aquifers over most of the project area, including a number of potential MAR and groundwater resource targets.

  • The Great Artesian Basin Water Resource Assessment (GABWRA) provided fundamental underpinning information for the Great Artesian Basin (GAB). Key data sets produced by GABWRA include contact surfaces between major aquifers and aquitards within the GAB. This poster covers the 3D visualisation of these surfaces in GOCAD (R) and in the Geoscience Australia World Wind 3D data viewer. Poster prepared for the International Association of Hydrogeologists congress 2013, Perth, Australia

  • Poster prepared for International Association of Hydrogeologists Congress 2013 Sonic drilling is a relatively new technology that was used successfully to obtain relatively uncontaminated and undisturbed continuous core samples with excellent (>99%) recovery rates to depths of 206m in unconsolidated fluvio-lacustrine sediments of the Darling River floodplain. However, there are limitations with the standard sonic coring method. Sands, in particular, are disturbed when they are vibrated out of the core barrel into the flexible plastic sampling tube. There can be changes to moisture content, pore fluid chemistry and sediment mineralogy on exposure to the atmosphere, even when the samples are processed and analysed soon after collection. The option exists during sonic drilling to encapsulate the core in rigid polycarbonate lexan tubes. Although this increases costs and reduces drilling rates, atmospheric exposure of the core during drilling is reduced to the ends of the lexan tubes before being capped. In addition, the tubes can be purged with an inert gas such as argon. Lexan coring is best carried out below the watertable as the heat from drilling dry clays can cause the polycarbonate to melt. In the study, 60 sonic holes (4.5 km) and 40 rotary mud holes (2 km) were obtained as part of a program to map and assess potential groundwater resources and managed aquifer recharge (MAR) targets over a large area (7,500 km2) of the Darling River floodplain. Two of the sonic bores were drilled to depths of 60 metres to obtain lexan-encapsulated core samples. These cores were used to obtain less perturbed samples for pore fluid analysis (salinity, major ions, trace metals, stable isotopes), textural analysis, and analysis of mineral phases to help assess aquifer clogging potential (using XRD, XRF, SEM). An additional advantage of the lexan coring was the recovery of encapsulated and intact sediment intervals for determining porosities, effective porosities, hydraulic conductivities, and other geophysical and petrophysical measurements. By painting some tubes black, sand samples were also successfully obtained for optically stimulated luminescence (OSL) dating. Alternatively, opaque black lexan can be made to order by the supplier. Overall, the superior sample integrity obtained from lexan coring enables a greater range of hydrogeological and hydrochemical parameters to be assessed.

  • This report describes the findings of the Great Artesian Basin Water Resource Assessment that have led to advancing the understanding of the GAB. It encapsulates findings that are presented in four region reports and a technical report on conceptualising the GAB that were prepared for the Assessment. Advancing the conceptual understanding of the GAB requires careful evaluation of the geological framework (i.e. the layers of rock), description of how the geology translates into hydrostratigraphy (i.e. the relative ability of specific layers to store and transmit water) and investigation of the groundwater conditions (i.e. watertable, groundwater levels, and inferred movement). It is the geological framework, hydrostratigraphy and groundwater conditions that are the basis for conceptualising water resources in the GAB. The conceptual understanding of the GAB provides the foundation for assessing water availability and providing guidance to water policy and water resource planning.

  • This report presents key results of groundwater level interpretations from the Upper Burdekin Groundwater Project in North Queensland, conducted as part of Exploring for the Future (EFTF)—an eight year, $225 million Australian Government funded geoscience data and information acquisition program focused on better understanding the potential mineral, energy and groundwater resources across Australia. The Upper Burdekin Groundwater Project is a collaborative study between Geoscience Australia and the Queensland Government. It focuses on basalt groundwater resources in two geographically separate areas: the Nulla Basalt Province (NBP) in the south and the McBride Basalt Province (MBP) in the north. This report interprets groundwater levels measured in both provinces by Geoscience Australia and the Queensland Government to provide recommendations for resource management. The NBP and MBP basalt aquifers are heterogeneous, fractured, vesicular systems. Several lava flows are mapped at surface in both provinces, and the degree of hydraulic connectivity between these flows is unclear. Although there was some uncertainty due to monitoring well construction issues, barometric efficiency analyses from supporting project documents suggest that the basalts of the NBP and MBP were unconfined where monitored during the EFTF project. That finding generally matches observations presented here. Longer term groundwater hydrographs suggest that groundwater levels have been declining in the NBP and MBP following major flooding in 2010-2011 related to one of the strongest La Niña events on record. Groundwater levels are yet to decline to pre-flood elevations in places. Importantly, these longer term hydrographs set the project in context: the EFTF monitoring period is only a small fraction of a much longer-functioning, dynamic groundwater system. Nulla Basalt Province The NBP is elongated east-west, and is situated entirely within the Burdekin River catchment. Volcanic vents in the west identify that area as the main extrusive centre. Regionally, groundwater migrates through the basalts of the NBP from the western high ground towards the Burdekin River in the east. Although lava flows of the NBP reach the Burdekin River, direct groundwater discharge in this area has not yet been proven. However, groundwater does discharge to various springs and surface watercourses in the NBP that are known tributaries of the Burdekin River. Despite the presence of many registered extraction bores, no clear signs of pumping were observed in groundwater hydrographs from the NBP during the EFTF monitoring period. Water levels in many bores responded to major rainfall events, ranging from a simple change in declining hydrograph slope to a water level increase of ~6.8 m in the central west. While some responses could have been induced by loading, electrical conductivity loggers and the extent of water level rise showed that many were clearly caused by recharge. At nested monitoring locations, groundwater levels remained commensurate with downward flow potentials throughout the EFTF monitoring period. McBride Basalt Province The MBP is approximately circular in plan, with volcanic vents present in a north-northeast trending band through the province centre. Lava flows extend away from the high ground of the province centre towards lower ground near the edges. In part due to its geometry, the MBP is situated within four river catchments; only surface water landing in the east flows into the Burdekin River. Regionally, groundwater migrates through the basalts of the MBP from the central high ground radially towards the edges. Direct groundwater discharge from the MBP basalts into the Burdekin River has been shown in this project. Similarly to the NBP, groundwater is also known to discharge to numerous springs and surface watercourses in the MBP. Water levels in many bores responded to major rainfall events. Responses ranged from a change in declining hydrograph slope to a water level increase of ~6.8 m in the southeast. While some responses could have been induced by loading, the extent of water level rise showed that others were clearly caused by recharge. No nested monitoring locations were installed for the EFTF project, so vertical head gradients are currently unknown. Although there are numerous registered extraction bores in the MBP, groundwater level response to pumping was only definitively identified in the east in bore RN12010016. However, several registered bores with high estimated yields have been installed in the northeast since EFTF fieldwork completion. It is possible that these higher yielding extraction bores may induce visible drawdown in monitoring bores in the future. Their high estimated yields may be associated with lava tubes; features not reported in the literature reviewed for this project for the NBP, but identified at surface and potentially in several Queensland Government bores drilled in the MBP. Conclusions and recommendations The Upper Burdekin Groundwater Project has provided abundant information on various aspects of the hydrogeology of the Nulla and McBride basalt provinces. General groundwater flow processes are understood at a regional scale for the EFTF monitoring period, but more detailed investigations and longer term monitoring are required to fully evaluate local conditions. One of the main observations of this study are the long term groundwater level declines in both the NBP and MBP following the 2010-2011 La Niña-associated floods. Groundwater levels are yet to reduce to pre-flood elevations in places, showing that the EFTF monitoring period represents only a small fraction of a much longer-functioning, dynamic groundwater system. It is unclear what, if any, contribution groundwater extraction has made to regional water level declines. Numerous correlations were assessed between groundwater hydrograph characteristics and potentially influencing factors, but the results were mostly inconclusive. There is uncertainty in hydraulic connectivity across lava flow boundaries and between intra-lava flow aquifers. Although interesting groundwater processes were identified at many bores, at the current bore spacing it is not generally possible to interpolate between locations with any certainty. Knowledge gaps and suggestions for further investigation are recorded in Section 5 of the report. The gaps identified should assist planning of future work to inform: - Further characterisation of groundwater resources. - Protection of groundwater dependent ecosystems. - Appropriate groundwater resource management.

  • This Southern Australian Fractured Rock Province dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. Crustal elements are crustal-scale geological regions primarily based on composite geophysical domains, each of which shows a distinctive pattern of magnetic and gravity anomalies. These elements generally relate to the basement, rather than the sedimentary basins. The South Australian Element comprises the Archean-Mesoproterozoic Gawler Craton and Paleo-Mesoproterozoic Curnamona Province, formed over billions of years through sedimentation, volcanism, magmatism, and metamorphism. The region experienced multiple continental-continent collisions, leading to the formation and breakup of supercontinents like Nuna and Rodinia, along with periods of extensional tectonism. Around 1,400 Ma, both the Gawler Craton and Curnamona Province were cratonised, and during the building of the Rodinia supercontinent (1,300-700 Ma), the present configuration of the region emerged. The area between the Gawler and Curnamona provinces contains Neoproterozoic to Holocene cover, including the Adelaide Superbasin, with the Barossa Complex as its basement, believed to be part of the Kimban Orogen. The breakup of Rodinia in the Neoproterozoic (830-600 Ma) resulted in mafic volcanism and extensional episodes, leading to the formation of the Adelaide Superbasin, characterized by marine rift and sag basins flanking the Gawler Craton and Curnamona Province. During the Mesozoic and Cenozoic, some tectonic structures were rejuvenated, while sedimentary cover obscured much of the now flatter terrain. Metamorphic facies in the region vary, with the Gawler and Curnamona provinces reaching granulite facies, while the Adelaide Superbasin achieved the amphibolite facies. The Gawler Craton contains rocks dating back to approximately 3,150 Ma, while the Curnamona Province contains rocks from 1,720 to 1,550 Ma. These ancient regions have undergone various deformation and metamorphic events but have remained relatively stable since around 1,450 Ma. The Adelaide Superbasin is a large sedimentary system formed during the Neoproterozoic to Cambrian, with distinct provinces. It started as an intracontinental rift system resulting from the breakup of Rodinia and transitioned into a passive margin basin in the southeast and a failed rift in the north. Later uplift and re-instigated rifting led to the deposition of thick Cambrian sediments overlying the Neoproterozoic rocks. Overlying basins include late Palaeozoic to Cenozoic formations, such as the Eromanga Basin and Lake Eyre Basin, which are not part of the assessment region but are adjacent to it.

  • This Summary Report provides an overview of the Regional Hydrogeological Characterisation of the Laura Basin, Queensland, Technical Report (GeoCat number 78881).

  • This Laura Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. The Laura Basin contains sedimentary rocks deposited between 168 and 102 million years ago during the Middle Jurassic to Early Cretaceous. The basin extends offshore beneath the Great Barrier Reef, and forms a bowl-shaped geologic feature. The strata have a maximum thickness of about 1,000 m in the north-central part of the onshore basin. Three main stratigraphic units comprise the stratigraphic succession of the Laura Basin, these being the Rolling Downs Group (Late Aptian to Albian, Cretaceous), the Gilbert River Formation (Lower Cretaceous to Jurassic) and the Dalrymple Sandstone (Upper to Middle Jurassic). The Rolling Downs Group was deposited in a shallow marine environment and has a basal shale unit (the Wallumbilla Formation) with minor siltstone and conglomerate bands overlain by marine silty and sandy claystone. The Gilbert River Formation was deposited in lagoonal to marginal marine environments and is dominated by clay-rich sandstone that is locally glauconitic and interbedded with minor calcareous siltstone, claystone and conglomerate. The Dalrymple Sandstone was deposited in lagoonal and fluvial environments and is dominated by sandstone with lesser claystone, siltstone, conglomerate, tuff and coal. The Laura Basin overlies older rocks of the Permian to Triassic Lakefield Basin, which extends northwards into surrounding marine waters, the Paleozoic metasedimentary rocks of the Hodgkinson region, associated with the Mossman Orogen, and Proterozoic basement rocks.

  • The Great Artesian Basin (GAB) is the largest groundwater basin in Australia. It underlies nearly one quarter of the continent, including parts of Queensland, New South Wales, South Australia and the Northern Territory. Groundwater from the GAB is a vital resource for agricultural and extractive industries, as well as for community water supply. It supports cultural values and sustains a range of groundwater-dependent ecosystems. Water managers from each jurisdiction manage their GAB resources using hydrogeological conceptualisations based on diverse historic nomenclature. However, GAB resources are continuous across borders and recent studies have shown high spatial variability in the hydrostratigraphic units across the basin. Therefore, there is a clear need to map the geological complexity consistently at a basin-wide scale in order to provide a hydrogeological framework to underpin effective long-term management of GAB water resources. The present study compiles and standardises existing and newly interpreted biostratigraphic and well formation picks from geological logs, 2D seismic and airborne electromagnetic data in a consistent chronostratigraphic framework. This framework was used to correlate geological units across the basin. Correlating the chronostratigraphy across the basin revealed age equivalent sediments deposited in different depositional environments during transgressive and regressive alternation events. Rigorous biostratigraphic control, using a common unified zonation scheme was used to identify lithological correlations. Rock properties were attributed based on sediment facies deposited during similar geological events. The approach provides a consistent way of mapping the distribution and properties of aquifers and aquitards across the whole GAB. The refined correlation of Jurassic and Cretaceous units between the Surat and Eromanga basins improves the resolution of our understanding of hydrogeological unit geometry and lithological variation that may influence groundwater flow within and between aquifers. The 3D hydrogeological architecture provides a model to refine hydrogeological conceptualisations and assist in improving basin water balance estimates. This Abstract was submitted/presented to the 2022 Australasian Groundwater Conference 21-23 November (https://agc2022.com.au/)

  • This Wiso Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. The Wiso Basin, a large intra-cratonic basin in the central Northern Territory, covers about 140,000 square kilometres and is part of the Centralian Superbasin. It is bounded by the Tennant and Tanami regions to the east and west, while a thrust fault separates it from the Arunta Region to the south. The basin adjoins the Georgina Basin in the southeast and joins the Daly and Georgina basins beneath the Cretaceous strata of the Carpentaria Basin in the north. The basin contains a relatively flat, undeformed succession of strata that gently dip towards the main depo-centre, the Lander Trough. About 80% of the basin consists of shallow middle Cambrian strata, while the remaining portion is within the Lander Trough, containing a diverse succession of Cambrian, Ordovician, and Devonian units. The depositional history and stratigraphy reveal that early Cambrian saw widespread basaltic volcanism, with the Antrim Plateau Volcanics forming the base layer and aquitard of the Wiso Basin. The middle Cambrian deposits include the Montejinni Limestone, the oldest sedimentary unit, followed by the Hooker Creek Formation and the Lothari Hills Sandstone. The uppermost Cambrian unit is the Point Wakefield beds. The Ordovician deposits consist of the Hansen River beds, primarily composed of fossiliferous sandstone and siltstone deposited in shallow marine environments. The Devonian unit capping the basin is the Lake Surprise Sandstone, found in the Lander Trough area, formed in shallow marine, shoreline, and fluvial environments during the Alice Springs Orogeny. Three main hypotheses have been proposed for the formation of the Lander Trough: a large crustal downwarp before thrusting of Paleoproterozoic rocks, the formation of a half-graben by faulting along the southern boundary, or the formation of two en-echelon synclines by vertical block movement. While the majority of the Wiso Basin consists of shallow middle Cambrian rocks, the Lander Trough presents a more varied stratigraphic sequence, holding potential for Neoproterozoic and early Cambrian rocks. However, further drilling is needed to verify this. The presence of similar units in neighbouring basins provides valuable insight into the basin's geological history and development.