Christmas Island is an Australian Territory located in the Indian Ocean about 2600 km north-west of Perth and 350 km southwest of Java. The Island is approximately 135 km2 in size and has a population of over 1800 residents. Although the average yearly rainfall is approximately 2000 mm/year, the Island has experienced periodic droughts that have threatened water supplies. Because of the highly porous rocks of the island, no permanent surface water bodies exist, and all fresh water is sourced from natural springs and caves. Currently, the Island¿s water supply is treated and stored in above-ground tanks, however, this only provides sufficient storage for a two-day supply if the underground water (groundwater) dries up or is contaminated. There is clearly a need for greater water security, although further investigations are required. An initial scoping study by Geoscience Australia confirmed that Christmas Island¿s geology and hydrogeology is complex and poorly understood. The Island is known for its phosphate-rich materials which have been mined since 1899. The Island¿s groundwater system is likely to be highly compartmentalized, with the potential for groundwater supplies to be identified in several locations across the Island. Geoscience Australia has recommended a second phase of investigations, focusing on 3-dimensional mapping of the Island using below ground imaging technologies (airborne electromagnetics and magnetics). These technologies, complemented by drilling and water sampling, will be used to identify and assess new potential underground water resources across the Island. Results from the new study will: - Provide critical new data and knowledge to enhance water security for the Island;. - Underpin development of a new economic planning framework; - Inform sustainable land management practices; and - Provide new data on the distribution of phosphate deposits.

This report presents key results from the Howard East project conducted as part of Exploring for the Future (EFTF), an Australian Government funded geoscience data and information acquisition program. The four-year (2016–20) program focused on better understanding the potential mineral, energy and groundwater resources in northern Australia. Groundwater is an essential part of Darwin’s water supply and is sourced from the Koolpinyah Dolostone Aquifer (KDA) at the Howard East Borefield (HEB) and McMinns Borefield, which are ~25 km to 30 km southeast of Darwin. Previous work suggests that electrical conductivity anomalies observed in airborne electromagnetic (AEM) data within 5 km of HEB may be caused by saline groundwater within the KDA that is separated from HEB by dykes and other geological features that effectively compartmentalise the aquifer (Fell-Smith & Sumner, 2011; Tan et al., 2012). Nevertheless, concerns have grown that increased groundwater use may result in migration of saline groundwater toward HEB, which could compromise the groundwater resource. We collected groundwater chemistry including isotopes, time-series groundwater salinity, AEM, and induction and gamma data to better understand the complexities of the KDA. We show that groundwater in the KDA typically has a fresh Mg-Ca-HCO3 type composition, as is expected for a dolomitic aquifer. Highly saline Na-Cl type groundwater with a composition similar to seawater exists at some locations as well as groundwater with a mixed composition. These findings confirm previous interpretations for the area (e.g. Fell-Smith & Sumner, 2011). We sampled saline groundwater on the opposite side of two dolerite dykes to HEB to its northeast. Age dating results for this sample cannot be used to determine whether this saline groundwater represents relict seawater or whether groundwater at this site is in hydraulic connection with the modern ocean. Our groundwater chemistry results also show that saline intrusion is occurring northwest of HEB. AEM data were collected to better characterise geological and hydrogeological features in the area. Estimates of bulk conductivity of the subsurface were derived by inverting AEM data using both deterministic and stochastic methods. Using these AEM inversions and other hydrogeological information, we characterised high-conductivity anomalies within 5 km of HEB and the upper surface of unweathered dolerite in the two dykes northeast of HEB. We interpreted conductivity anomalies as pyritic shales, although drilling is required to investigate the salinity of groundwater in the KDA in this area. Where we were able to resolve the upper surface of unweathered material in the two dykes using the AEM, we found that it commonly occurs below sea level. Characterising the geometry of these dykes will aid in assessing their role in aquifer compartmentalisation. Our findings contribute to building a robust conceptual understanding of the KDA and will guide future investigations into the groundwater system. A number of other products exist for the EFTF Howard East project. The findings of this report are integrated with hydrodynamic analyses undertaken by Woltmann (in prep.) and reported in Haiblen et al. (2020). Hydrochemistry data presented here are contained in McGrath-Cohen et al. (2020), water level and salinity monitoring data can be found in Turner et al. (2020), AEM data are in Ray et al. (2020b), and induction and gamma data are in Tan et al. (2020).

This report presents a summary of the groundwater and surface water hydrochemistry data release from the Daly River project 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. This data release records the groundwater sample collection methods and hydrochemistry and isotope data from monitoring bores in the Daly River project area, Northern Territory (NT). The Daly River project is a collaborative study between Geoscience Australia and the NT Government. Hydrochemistry and isotope data were collected from existing bores in the Daly River area. The sampling methods, quality assurance/quality control procedures, analytical methods and results are included in this report and all hydrochemistry data are available for download from the link at right.

This report presents a summary of the groundwater and surface water hydrochemistry data release from the Howard East project 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. This data release records the groundwater and surface water sample collection methods and hydrochemistry and isotope data from monitoring bores in the Howard East project area, Northern Territory (NT). The Howard East project is a collaborative study between Geoscience Australia and the NT Government. Hydrochemistry and isotope data were collected from existing bores in the Howard East area. The sampling methods, quality assurance/quality control procedures, analytical methods and results are included in this report and all hydrochemistry data are available for download from the link at right.

This animation shows how groundwater sampling is conducted. It is part of a series of Field Activity Technique Engagement Animations. The target audience are the communities that are impacted by GA's data acquisition activities. There is no sound or voice over. The 2D animation includes a simplified view of what groundwater sampling equipment looks like, what the equipment measures and how scientists use the data.

<div>Reliable water availability is critical to supporting communities and industries such as mining, agriculture and tourism. In remote and arid areas such as in the Officer – Musgrave region of central Australia, groundwater is the only viable source of water for human and environmental use. Groundwater systems in remote regions such as the Musgrave Province are poorly understood due to sparse geoscientific data and few detailed scientific investigations. The Musgrave palaeovalley module will improve palaeovalley groundwater system understanding in the Musgrave Province and adjacent basins to identify potential water sources for communities in the region. This report summarises the state of knowledge for the region on the landscape, population, water use, geology and groundwater systems. An analysis of the current and potential future water needs under different development scenarios captures information on how water is used in an area covering three jurisdictions and several potentially competing land uses.</div><div>The Musgrave Palaeovalley study area is generally flat, low-lying desert country. The Musgrave, Petermann, Mann and Warburton ranges in the centre of the area are a significant change in elevation and surface materials, comprising rocky hills, slopes and mountains with up to 800&nbsp;m of relief above the sand plains. Vegetation is generally bare or sparse, with isolated pockets of grassy or woody shrub lands. Soils are typically Tenosols, Rudosols and Kandosols.</div><div><br></div><div>There are four main hydrogeological systems in the study area. These are the fractured and basement rocks, local Quaternary sediments regional sedimentary basins and palaeovalley aquifers. These systems are likely to be hydraulically connected. Within palaeovalleys, three main hydrostratigraphic units occur. The upper Garford Formation is a sandy unconfined aquifer with a clay rich base (lower Garford Formation) which acts as a partial aquitard where present. The Pidinga Formation represents a coarser sandy or gravelly channel base, which is partly confined by the lower Garford Formation aquitard. The aquifers are likely to be hydraulically connected on a regional scale. Further to the west, equivalent units are identified and named in palaeovalley systems on the Yilgarn Craton. </div><div><br></div><div>Groundwater is recharged by episodic, high-intensity rainfall events and mostly discharges via evapotranspiration. Recharge is higher around the ranges, and lower over the flatter sand plains. Palaeovalley aquifers likely receive some groundwater inflow from underlying basin systems and fractured rock systems. Regional groundwater movement is topographically controlled, moving from the ranges towards surrounding areas of lower elevation. In some palaeovalleys groundwater discharges at playa lakes. Water table gradients are very low. More groundwater isotope and tracer data is required to understand potential connectivity between basin, fractured rock and palaeovalley systems.</div><div>Groundwater quality is brackish to saline, although pockets of fresher groundwater occur close to recharge areas and within the deeper and coarse-grained Garford Formation. Groundwater resources generally require treatment prior to use Most groundwater in the region is suitable for stock use. </div><div><br></div><div>Existing palaeovalley mapping is restricted to inferring extents based on landscape position and mapped surface materials. Utilising higher resolution digital elevation models and more recently acquired remotely sensed data will refine mapped palaeovalley extents. Improving the modelling of the distribution and depth of palaeovalleys in greater detail across the region is best aided through interpretation of airborne electromagnetic (AEM) data.</div><div>Based on the successes of integrating AEM with other geoscientific data in South Australia, we have acquired 25,109 line km of new AEM across the WA and NT parts of our study area. We will integrate this data with reprocessed and inverted publicly available AEM data, existing borehole information, existing and newly acquired hydrochemical data, and new surface magnetic resonance data to model the three dimensional distribution of palaeovalleys in the study area. We will use these models and data as the basis for conceptualising the hydrogeology of the palaeovalley systems, and provide information back to local communities and decision-makers to inform water management decisions. The data will also provide valuable precompetitive information for future economic development in the region.</div><div><br></div>

This Money Shoal 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 Money Shoal Basin is a large passive margin basin in northern Australia, mainly located in the offshore Arafura Sea. Its sedimentary succession spans from the Mesozoic to the Cenozoic era, reaching a maximum thickness of 4,500 m in the northwest but thinner, less than 500 m, in central and eastern areas. The basin overlays the Neoproterozoic to Permian Arafura Basin and older Proterozoic rocks of the Pine Creek Orogen and McArthur Basin. It is bounded by the Bonaparte Basin to the west and the Carpentaria Basin to the east. The southern margin of the basin occurs onshore and is an erosional feature, although scattered remnant outliers of Money Shoal Basin rocks occur in isolated areas to the south and south-east of Darwin. The northern parts remain less explored, situated beyond Australia's maritime border with Indonesia. The basin's Mesozoic sediments were deposited during passive margin subsidence, and consequently remain relatively undeformed. Compressional tectonics were later initiated during the Cenozoic collision between the Indo-Australian plate and Southeast Asia, causing minor structural disruptions along the northwest margin of the Australian plate. Most of the sediments in the basin were deposited in shallow to marginal marine environments, with minor evidence for short-lived episodes of deltaic and fluvial deposition in some areas. The sedimentary packages in the offshore basin are divided into four groups: Troughton Group equivalent, Flamingo Group equivalent, Bathurst Island Group, and Woodbine Group equivalent. Onshore, the stratigraphic succession is limited to the Plover Formation equivalent, Bathurst Island Group, and the Eocene Van Diemen Sandstone. The Troughton Group extends from the Bonaparte Basin into western parts of the Money Shoal Basin, and chiefly consists of sandstone. The Flamingo Group, identified offshore, is considered equivalent to its Bonaparte Basin counterpart, characterized by sandstone and mudstone deposits, suggesting fluvial and deltaic settings. The Bathurst Island Group dominates onshore, composed mainly of fine-grained claystone, marl, and siltstone. The Woodbine Group is the uppermost unit, and is equivalent to the Woodbine Group of the Bonaparte Basin, consisting of Cenozoic deposits, primarily sandstone and claystone, indicating shallow marine and deltaic environments.

This Bonaparte 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 Bonaparte Basin is a large sedimentary basin off the north-west coast of Australia, encompassing both offshore and onshore areas. It has undergone multiple phases of extension, deposition, and tectonic inversion from the Paleozoic to Cenozoic periods. The Petrel Sub-basin, situated on the eastern margin, exhibits a north-west trending graben/syncline and exposes lower Paleozoic rocks onshore while transitioning to upper Paleozoic, Mesozoic, and Cenozoic sediments offshore. Onshore, the basin's geological structures reflect two dominant regimes: north to north-north-east trending Proterozoic basement structures associated with the Halls Creek Mobile Zone, and north-north-west trending basin structures linked to the rifting and later compressional reactivation of the Petrel Sub-basin. The Petrel Sub-basin has experienced growth and tectonic inversion since the Paleozoic, marked by volcanic activity, deposition of clastics and carbonates, and extension events. During the Devonian, extension occurred along faults in the Ningbing Range, leading to the deposition of clastics and carbonates. The Carboniferous to Permian period witnessed offshore extension associated with the Westralian Superbasin initiation, while onshore deposition continued in shallow marine and transitional environments. Thermal subsidence diminished in the Early Permian, and subsequent compression in the mid-Triassic to Early Jurassic reactivated faults, resulting in inversion anticlines and monoclines. After the Early Jurassic, the sub-basin experienced slow sag with predominantly offshore deposition. Post-Cretaceous deformation caused subsidence, and an Early Cretaceous transgression led to shallow marine conditions and the deposition of chert, claystone, and mudstones. Mid-Miocene to Recent compression, related to continental collision, reactivated faults and caused localized flexure. The stratigraphy of the onshore Bonaparte Basin is divided into Cambro-Ordovician and Middle Devonian to Early Permian sections. Studies have provided insights into the basin's stratigraphy, with an update to the Permo-Carboniferous succession based on seismic interpretation, borehole data integration, field validation, and paleontological information. However, biostratigraphic subdivision of the Carboniferous section remains challenging due to poorly constrained species definitions, leading to discrepancies in the application of biozonations.

This Karumba 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 Karumba Basin is a shallow geological basin in Queensland, Australia, composed of sedimentary rocks and unconsolidated sediments that cover the Mesozoic Carpentaria Basin. Deposition started during the Late Cretaceous to Early Paleocene and has continued into the Holocene. The basin extends from western Cape York Peninsula into the Gulf of Carpentaria, where it connects with Cenozoic sediment deposits in Papua New Guinea. Although the sediments in both areas share lithostratigraphic and biostratigraphic similarities, their tectonic histories differ. The basin's structural geology is relatively uniform, with a significant downwarp known as the Gilbert-Mitchell Trough in Cape York Peninsula and another depocenter offshore in the Gulf of Carpentaria. The depositional history and stratigraphy of the Karumba Basin can be divided into three cycles of deposition, erosion, weathering, and the formation of stratigraphic units. The earliest cycle (the Bulimba Cycle) began in the Late Cretaceous to Early Paleocene, with episodes of significant uplift along the eastern margins of the basin. This resulted in the deposition of the Bulimba Formation and the Weipa Beds, primarily consisting of claystone, sandstone, conglomerate, and siltstone with minor coal layers. This cycle was followed by a period of planation and deep weathering, creating the Aurukun Surface. The second cycle (the Wyaaba Cycle) was initiated by large-scale earth movements along the Great Dividing Ranges, forming much of the eastern boundary of the Karumba Basin, and leading to the formation of the Wyaaba beds and other equivalent units. These beds consist mainly of fluvial to paralic clay-rich sandstone, conglomerate, siltstone, and claystone. In the south-west, Oligocene to Pliocene limestone deposits also formed in lacustrine settings, and were sourced from and deposited upon the underlying Georgina Basin. The cycle ended with ensuing periods of erosion and weathering and the development of the Pliocene Kendall Surface, as well as widespread basaltic volcanism. The final cycle (the Claraville Cycle) started in the Pliocene and continues to the present. It has experienced several episodes of uplift and deposition controlled by sea level change, climate variability and volcanism in the south. The Claraville beds are unconsolidated sediments, chiefly comprised of clayey quartzose sand and mud with minor gravels, reaching approximately 148 m thickness offshore, and approximately 70 m onshore. As this cycle is still ongoing, no terminal surface has been formed, and most units consist of unconsolidated surficial sediments.

This Ord 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 Ord Basin, an intracratonic sedimentary basin, covers about 8000 square kilometres on the border of Western Australia and the Northern Territory. It was once part of the extensive Centralian Superbasin, which deposited sediments across central and northern Australia from the Proterozoic to early Palaeozoic era. The Ord Basin comprises three synclines with up to 2500 m of Cambrian and Devonian sedimentary rocks, separated by major faults and Proterozoic basement highs. The basin's northern boundary is defined by the Halls Rewards Fault and Proterozoic basement rocks, separating it from the Bonaparte Basin. The western edge overlies rocks of the Paleoproterozoic Halls Creek Orogen, while the eastern margin is separated from the Wiso Basin by volcanic Kalkarindji Province and Proterozoic Birrindudu and Victoria basins. The southern boundary is formed by the Negri Fault and Proterozoic basement highs. The depositional history of the Ord Basin can be divided into three phases. The early Cambrian witnessed extensive basaltic volcanism, forming the Antrim Plateau Volcanics. Subsequently, the Cambrian marine transgression deposited carbonates and clastic rocks of the Goose Hole Group, including the Elder and Negri Subgroups. The Late Devonian saw the deposition of continental sandstones and conglomerates of the Mahony Group. Throughout the basin's evolution, tectonic movements and erosional processes shaped its present configuration. The Alice Springs Orogeny (450 to 300 Ma) caused deformation and landscape changes, resulting in the deposition of the Mahony Group. Periodic reactivation of growth faults in the underlying Birrindudu Basin and subsequent erosion contributed to the basin's current structure. The Ord Basin's three synclines are the Hardman Syncline (southern and largest), the Rosewood Syncline (central), and the Argyle Syncline (northern). The Hardman Syncline holds the full succession of basin strata.