Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia's Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable H-3 (0.43 TU), and activities of radiocarbon a(14)C (14.1 - 95.3 pMC) and chlorine-36 (RCl)-Cl-36 (78.1 x 10(-15) - 161 x 10(-15)) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO3 and F concentrations and heavy fraction hydrocarbons (>100 mu g/L C-10-C-40) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine's groundwater impacts, which was the basis of the mine's approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.

An unusual north-south line of similar to 50 springs along the eastern margin of the Eromanga Basin, northeastern Australia, discharge from the outcrop margin of the Hutton Sandstone aquifer, which is folded so the springs are fed by easterly groundwater flow, in contrast to the dominant westwards flow within the Eromanga Basin. This means that the effective recharge area of the Hutton Sandstone in this region is less than previously estimated. The springs occur as pools which represent water-table windows, with groundwater 'streams' flowing from one side to the other along subhorizontal joints within a near-surface silcrete layer developed on the Hutton Sandstone. The springs are recharged through fractures in the silcrete, feeding laminar groundwater flow through the Hutton Sandstone until its outcrop terminates. At this point flow transfers into the overlying silcrete as concentrated pathways probably localised along broad, shallow troughs in the silcrete beneath surface drainage lines. The springs are surrounded by white siliceous precipitates with a groundmass of intergrown amorphous silica and kaolinite; this may have been allophane originally. Most silica springs are geothermal, yet the eastern Alice Tableland springs have surface temperatures. The elevated dissolved Si levels in these springs are due to dissolution of relatively soluble silica microcrystallites within the silcrete through which the spring water flows. The lack of calcite precipitation from the springs reflects the low Ca concentrations of the groundwater, probably due to strong Ca uptake by plants.

Abstract Developing conceptual models is a critical step in hydrogeological studies that should utilise multiple lines of evidence and data types to minimise conceptual uncertainty, particularly in data-sparse systems. This study used new and existing major ion and isotope (O, H, Sr, C) data sets to refine a previous hydraulic-head-based conceptual model of the Galilee Basin (Australia). The analyses provide evidence for the locations of recharge and discharge areas and determine hydrochemical processes along flow paths to improve understanding of potential source waters to the Doongmabulla Springs Complex (DSC) and to infer mixing within, or exchange between aquifer units. There was good agreement between previously inferred recharge and discharge areas defined using hydraulic head data and interpretations from hydrochemical evolution along groundwater flow pathways, at least where data were available. Major ion and isotope data suggest that the DSC likely receives water from both a relatively shallow, local flow path and a deeper regional flow path. This observation is relevant to previous concerns about threats to the DSC, as mine-induced drawdown may impact the relative contributions to spring discharge from different recharge sources and aquifers. Silicate weathering in the deeper Clematis Formation and Dunda Beds, and evapotranspiration in the overlying Moolayember Formation have strong control on the total dissolved solids content. These findings suggest that the Clematis Formation and Dunda Beds are hydrochemically distinct from the Moolayember Formation, with limited exchange between these aquifers, which has important implications for model conceptualisation and ongoing monitoring of mining activities in the Galilee Basin.

The catchment geomorphology of the Zarqa River in Jordan was investigated using a three-dimensional model and interpretation of geology. There are three major elements that control the Zarqa River catchment and its drainage networks: lithological units, faults and paleovolcanism. The upper catchment is typical of a youthful stage of river development with relatively recent lava fields that have infilled and reduced the original size of the catchment. The lower part of the catchment includes a convex profile probably resulting from the coalescence of knickpoints generated by uplift along the Dead Sea fault. The lower and middle sections of the catchment contain remnants of an older, wider valley, 200–500 m above the present river level, that probably formed during a hiatus in tectonic and volcanic activity from 22 to 13 Ma.

Developing conceptual models is a critical step in hydrogeological studies that should utilise multiple lines of evidence and data types to minimise conceptual uncertainty, particularly in data-sparse systems. This study used new and existing major ion and isotope (O, H, Sr, C) data sets to refine a previous hydraulic-head-based conceptual model of the Galilee Basin (Australia). The analyses provide evidence for the locations of recharge and discharge areas and determine hydrochemical processes along flow paths to improve understanding of potential source waters to the Doongmabulla Springs Complex (DSC) and to infer mixing within, or exchange between aquifer units. There was good agreement between previously inferred recharge and discharge areas defined using hydraulic head data and interpretations from hydrochemical evolution along groundwater flow pathways, at least where data were available. Major ion and isotope data suggest that the DSC likely receives water from both a relatively shallow, local flow path and a deeper regional flow path. This observation is relevant to previous concerns about threats to the DSC, as mine-induced drawdown may impact the relative contributions to spring discharge from different recharge sources and aquifers. Silicate weathering in the deeper Clematis Formation and Dunda Beds, and evapotranspiration in the overlying Moolayember Formation have strong control on the total dissolved solids content. These findings suggest that the Clematis Formation and Dunda Beds are hydrochemically distinct from the Moolayember Formation, with limited exchange between these aquifers, which has important implications for model conceptualisation and ongoing monitoring of mining activities in the Galilee Basin.

The White Hills Gravel is the coarsest fluvial gravel within Victoria, southeastern Australia, and outcrops discontinuously across a substantial part (>35 000 km(2)) of this region. It overlies a major regional unconformity representing >300 Ma, and is dominated by conglomerate (61% of beds), with less abundant sandy lithofacies (36% of beds) and rare mudstones (3% of beds). The sedimentary characteristics of the basal conglomerates (e.g. thick bedding, common boulders, very poor sorting and in places chaotic appearance) indicate deposition by significant paleofloods, including debris floods, within braided streams that had similar flow directions to the modern drainage. Paleohydraulic calculations estimate that the paleofloods had discharges exceeding >7200 m(3) s(-1), over 25 times the largest recorded floods in the same valleys. These paleofloods were probably caused by exceptionally severe storm systems, consisting of many individual thunderstorms. Deposition of the White Hills Gravel has previously been attributed to the mid-Cretaceous uplift that affected southeastern Australia, but the maximum possible age of the formation (early Paleocene) is too young for this to be a viable explanation. Instead, the White Hills Gravel may have been deposited during a period of increased precipitation at the Paleocene-Eocene Thermal Maximum (ca 56 Ma), when an intensification of the hydrological system generated significant sediment responses within fluvial systems around the world. Modelling indicates that this climatic event had a substantial impact in Victoria, where increases in mean annual precipitation (50-60%) and the most extreme rainfall rates achieved by the strongest storms (60-70%) were some of the largest globally, and frequent and intense Atmospheric Rivers were an important part of the hydrological system. These factors, together with a period of disturbed vegetation cover, resulted in major paleofloods that could have deposited the coarse-grained conglomerates of the White Hills Gravel.

Macrocrystalline quartz is an abundant raw material used widely for artefact manufacture. In Australia its procurement, reduction and use are now considered more complex than previously thought. The analysis of a mid-late Holocene assemblage from Moolarben in eastern Australia demonstrates how geoarchaeological variability influences the manufacture of macrocrystalline quartz artefacts. The different flaking proprieties of the three available macrocrystalline quartz varieties (opaque milky, semi-transparent milky and crystal), along with the type of source, influenced core reduction as well as the resulting flake form and its use. Moreover, to counter the costs of flaking problems of macrocrystalline quartz, different reduction strategies were used for cores obtained from primary reef/vein outcrops and those from secondary sources (water-rolled alluvial pebbles). The systematic reduction strategies used to prepare cores and remove the elongated flakes suitable for backed artefacts represent an adaption of already established flaking strategies, and suggest that the disappearance of backed artefacts in Late Holocene assemblages from eastern Australia (associated with an increase in the use of macrocrystalline quartz in some areas), did not represent a dramatic change in technology, but rather an effective and significant innovation which ultimately meant that backing was no longer required. This technological shift is also reflected in the benefits of flaking a locally abundant material which retains a strong and sharp working edge. Measuring geoarchaeological variability adds greater insights into the costs and benefits of manufacturing macrocrystalline quartz artefacts, and these insights are applicable to studies worldwide.

Fossil plants in sub-basaltic and fluvial silcretes differ in their geological setting, silica source, taphonomy, preservation and the plants and communities represented: these factors collectively indicate distinct silicification pathways. This review shows that the floras in sub-basaltic silcretes are mostly autochthonous, being derived from the local vegetation, whereas the floras in inland fluvial silcretes are transported and allochthonous. The floras in both are three-dimensionally preserved. The plants in sub-basaltic silcretes are usually permineralised, preserving internal anatomy and cellular morphology, whereas the plants in inland fluvial silcretes occur as moulds/impressions that may preserve epidermal and surface features. Both types of silcrete floras offer insights into past environments and ecological drivers. Terrestrial (ground-dwelling) ferns are frequently preserved in situ in sub-basaltic silcretes whilst in the inland fluvial silcretes they are represented only by pinnule fragments or abscised pinnules. The extraordinary anatomical preservation of soft tissues in sub-basaltic silcretes, e.g., exocarps of fruits, bark on wood, actively growing vegetative shoots (fern croziers) and root nodules, is evidence of rapid burial by volcanogenic sediments and subsequent silicification by silica-rich groundwaters. The source of silica was hydrothermal fluids released at the time of eruption and/or the weathering of overlying volcanics, and the acidic (humic) conditions resulting from buried plant material provided ideal geochemical conditions for silica precipitation and plant permineralisation. The sub-basaltic silcrete floras formed contemporaneously with Eocene-Miocene volcanism in eastern Australia, whereas the formation of inland pedogenic and fluvial silcretes was probably initiated during the Paleocene-Eocene Thermal Maximum (PETM). The fine surface preservation of plants in inland fluvial silcrete floras indicates rapid burial but no organic material is preserved, probably because oxidising groundwaters stripped out the organics before silicification occurred. The comparatively less silica-rich groundwaters associated with fluvial silcretes and the sandy substrates would have further contributed to the loss of plant material. (c) 2024 Published by Elsevier B.V. on behalf of International Association for Gondwana Research.

Elevated areas on basalt lava flows, locally known as stony rises, are volcanic landforms located in the Victorian Volcanic Plain (VVP) in southeastern Australia. Stony rises are recognized as having high geological, ecological, and cultural values. Currently, the mapping of stony rises is carried out on a study-by-study basis, via traditional field surveys. Mapping of such features could be performed more rapidly and at a landscape level by utilizing remotely sensed datasets such as LiDAR, satellite and aerial imagery, and geophysical data, and applying detection techniques such as machine learning. This study incorporates an ensemble of remotely sensed data and predictor variables to characterize stony rise morphology through a machine learning approach that uses an object based Random Forest. We were able to successfully detect stony rises across various lava flows in the VVP. Future geomorphological studies should aim to incorporate the use of spectral and geophysical predictor variables for large area landform detection and analysis.

Karst landforms provide insights into landscape evolution and paleoclimate but are inherently challenging to date. An ancient interval of particularly intense weathering of Western Australian Pleistocene aeolianites is recorded in a spectacular pinnacle karst landscape with associated ferricrete nodules. (U-Th)/He dating of the ferricrete nodules revealed an age of 102.8 + 10.6/-11.4 thousand years, corresponding to marine isotope stage 5c. The (U-Th)/He age thus directly dates the wettest interglacial period in the region over the last 500 thousand years, which was responsible for the dissolution that formed the pinnacles. The reliability of the ferricrete (U-Th)/He age is supported by bounding optically stimulated luminescence and U-Th dates on associated aeolianites and carbonate precipitates, respectively. A (U-Th)/He approach is globally applicable to aeolianites with associated ferricretes, allowing more accurate dating of the environmental changes affecting these lithologies, and temporally constraining rapid Pleistocene climatic oscillations to better contextualize the associated evolution of the biosphere.

The surface and subsurface karst features of the Eocene limestone plateaus along the Middle Nile Valley in Egypt were formerly believed to be epigene in origin and to have developed during post-Eocene pluvial periods. However, the morphology of the caves and their restriction to particular stratigraphic intervals suggests that they are hypogene. The geochemistry and mineralogy of the soft, thick-bedded, brown/black cave infills shows that these sediments originated from hydrothermal processes, as evidenced by their Fe, Mn, Co, Ni, and Cu concentrations. Thus, the karst features are hypogene and probably formed during the opening of the Red Sea Rift at the end of the Oligocene and early Miocene. At this time, there was abundant volcanic activity, as shown by basalt lavas ~70 km northwest of Assiut; this triggered the release of large amounts of CO2 that made the hydrothermal waters acidic and dissolved the caves.

The Arabian Desert is characterised by very low rainfall and high evaporation, yet over 210 springs are on its northeastern edge in central Iraq along the Abu Jir lineament, which represents the western depositional margin of a foreland basin infilled by the floodplain sediments of the Tigris and Euphrates Rivers; there is little evidence of faulting. The springs discharge from gently east-dipping Paleocene–Eocene limestones, either where groundwater flowpaths intersect the ground surface or where groundwater flow is forced to the surface by confining aquitards. Calculated annual recharge to the aquifer system across the Arabian Desert plateau (130–500 million m3) is significant, largely due to rapid infiltration through karst dolines, such that karst porosity is the primary enabler of groundwater recharge. The recharge is enough to maintain flow at the Abu Jir springs, but active management of groundwater extraction for agriculture is required for their long-term sustainability. The hydrochemistry of the springs is determined by evaporation, rainfall composition (high SO4 concentrations are due to the dissolution of wind-blown gypsum in rainfall), and plant uptake of Ca and K (despite the sparse vegetation). Limestone dissolution has relatively little impact; many of the springs are undersaturated with respect to calcite and lack tufa/travertine deposits. The springs at Hit-Kubaysa contain tar and high levels of H2S that probably seeped upwards along subvertical faults from underlying oil reservoirs; this is the only location along the Abu Jir lineament where deep-seated faults penetrate to the surface. The presence of hydrocarbons reduces the Hit-Kubaysa spring water and converts the dissolved SO4 to H2S.

Fifty years have passed since the first systematic archaeological surveys and excavations were conducted in Lutruwita (Tasmania). Despite numerous Late Pleistocene archaeological discoveries in the southwest region, no indisputable pre-Holocene sites have been found in eastern Tasmania. This profound difference raises questions about how Aboriginal people utilised the Lutruwita landscape; first as a projecting peninsula into the Southern Ocean and then as an island cut off by rising seas c.14000 years ago.To examine the difference between east and west further, legacy data excavated by one of us (RJ) in 1964 at the Oatlands OL1 site and stored at the Tasmanian Museum and Art Gallery (TMAG) has been analysed. The results of pXRF chemical analysis of artefact raw material, radiocarbon dating and studies of faunal remains have produced information that highlights the Holocene interaction between people in eastern Lutruwita. Despite the current lack of Late Pleistocene evidence from eastern Lutruwita, this pattern appears to be different from land use models for Late Pleistocene southwestern Lutruwita. With new information from the OL1 rock shelter site we can now contrast the Late Pleistocene hunting economics with the exceptionally well-preserved faunal remains found in the Holocene site, OL1. Cinquante ans se sont & eacute;coul & eacute;s depuis que les premi & egrave;res enqu & ecirc;tes arch & eacute;ologiques et fouilles syst & eacute;matiques ont & eacute;t & eacute; men & eacute;es & agrave; Lutruwita (Tasmanie). Malgr & eacute; de nombreuses d & eacute;couvertes arch & eacute;ologiques de la fin du Pl & eacute;istoc & egrave;ne dans la r & eacute;gion du sud-ouest, aucun site pr & eacute;-Holoc & egrave;ne indiscutable n'a & eacute;t & eacute; trouv & eacute; dans l'est de la Tasmanie. Cette profonde diff & eacute;rence soul & egrave;ve des questions sur la fa & ccedil;on dont les Aborig & egrave;nes ont utilis & eacute; le paysage de Lutruwita; d'abord comme une p & eacute;ninsule projet & eacute;e dans l'oc & eacute;an Austral, puis comme une & icirc;le coup & eacute;e par la mont & eacute;e des mers il y a environ 14 000 ans.Pour examiner davantage la diff & eacute;rence entre l'est et l'ouest, les donn & eacute;es h & eacute;rit & eacute;es fouill & eacute;es par l'un d'entre nous (RJ) en 1964 sur le site Oatlands OL1 et stock & eacute;es au Tasmanian Museum and Art Gallery (TMAG) ont & eacute;t & eacute; analys & eacute;es. Les r & eacute;sultats de l'analyse chimique pXRF de la mati & egrave;re premi & egrave;re des artefacts, de la datation au radiocarbone et des & eacute;tudes sur les restes de la faune ont produit des informations qui mettent en & eacute;vidence l'interaction de l'Holoc & egrave;ne entre les habitants de l'est de Lutruwita. Malgr & eacute; l'absence actuelle de preuves du Pl & eacute;istoc & egrave;ne tardif de l'est de Lutruwita, ce mod & egrave;le semble & ecirc;tre diff & eacute;rent des mod & egrave;les d'utilisation des terres pour le sud-ouest du Pl & eacute;istoc & egrave;ne tardif de Lutruwita. Avec de nouvelles informations provenant du site d'abri rocheux OL1, nous pouvons maintenant comparer l'& eacute;conomie de la chasse du Pl & eacute;istoc & egrave;ne tardif avec les restes fauniques exceptionnellement bien conserv & eacute;s trouv & eacute;s sur le site de l'Holoc & egrave;ne, OL1.

A basalt lava plain covers much of central and western Victoria in Australia. Many of the younger flows (<1 Ma) have hummocky surfaces with abundant tumuli and lava rises, known locally as stony rises due to the protruding basalt boulders. Stony rises are noteworthy geologically but have ecological importance and are culturally significant to Aboriginal Australians. Ecologically, stony rises host many native plant species. Culturally, stony rises provide evidence of Aboriginal land use and occupation through the presence of artefact deposits. Currently, mapping of stony rises is carried out by conducting field surveys on a study-by-study basis. This could be performed more rapidly using remote sensing datasets such as LiDAR, satellite and aerial imagery, and geophysical data. This research mapped stony rises in an area that is experiencing rapid urban development using a combination of remotely sensed datasets that characterise the morphology of stony rises through a Machine Learning approach that utilises Object Based Image Analysis (OBIA) segmentation and Random Forests (RF) classification techniques. The research successfully identified stony rises in the landscape to an accuracy of 89.97 %, with 314 potential new stony rise sites identified. The research identified the most important predictor variables were slope, local elevation, the concentrations of thorium and uranium (obtained from airborne radiometric data), aeromagnetic data (total magnetic intensity), the Normalised Difference Water Index (NDWI), and the Clay Mineral Ratio. The results from this study lay a foundation for standardising the definition of a stony rise within Australia. Furthermore, by utilising various predictor variables, this study highlights the success of a multifaceted approach into detecting a specific landform at a landscape level.

In north-western Australia the extensive Kimberley karst is world-famous as one of the best-preserved fossil reef systems in the world. Despite being deposited 360–380 million years ago, the original features of the reef are still clearly visible. The karst forms a series of limestone ranges with bare limestone pavements strongly dissected along joints to form inhospitable jagged ridges and spires. The major rivers in the region have incised gorges through the limestone ranges. Most Kimberley caves are joint-controlled mazes beneath grikefields, and, like similar caves across northern Australia, formed under the influence of the monsoonal rainfall that characterises this region. Runoff from intense rainfall events during the wet season pours through joints and grikes into the caves beneath, and is dissolving the caves from the top down.

The Southeastern Highlands in eastern Victoria contain several outcrops of Late Silurian - Early Devonian limestone, the largest of which, at Buchan, contains over 700 caves and karst-related features. The topographically higher vertical caves developed along joints and sometimes form mazes; the topographically lower subhorizontal systems often run parallel to the strike of the limestone. Cave development has occurred over millions of years; the caves could have begun to form as much as 90 million years ago, and the topographically higher caves were drained by 2–3 million years ago and have been open ever since.

AustraliaThe large volcanic province in western Victoria (~19,000 km2) has over 700 eruption points. Activity started ~8 million years ago and peaked around 2 million years ago; the most recent eruptions were ~5000 years ago. Over 50 lava caves are known; the oldest is at Parwan in lavas 2–4 million years old. The most extensive are in lavas 35–50,000 years old around Mount Napier and Budj Bim, and range from isolated small chambers (“lava blisters”) to anastomosing passages in several interconnected levels that represent stacked lava lobes. The largest lava conduits, in the Harmon Valley flow, are up to 25 m wide and 18 m high, and form a chain 1.3 km long. A suite of phosphate minerals, including 5 new minerals, has been described from bat guano in two of the lava caves.

Within north-eastern Australia, the northernmost karst areas, Mitchell–Palmer and Chillagoe, are characterised by spectacular serrated limestone towers. The towers are densely cavernous and contain over 1000 caves, which are mostly joint-controlled mazes of rift passages developed on one level, with entrances are on the sides of towers. Passages frequently connect upwards with grikes, so daylight chambers are common. The towers may have originated in the early Mesozoic, but development of the caves within the towers, as well as the surface karren features, occurred once the tropical monsoonal climate, with its pronounced wet and dry seasons, became established across northern Australia.