Murray Basin Research Articles

Sequences and biofacies packages in the mid‐Cenozoic Gambier Limestone, South Australia: Reappraisal of foraminiferal evidence

The mid to outer neritic carbonates of the Gambier Limestone (Upper Eocene to lower Middle Miocene) can be divided into seven units by using criteria of sequence stratigraphy and foraminiferal biofacies. The boundaries fall mainly on erosional surfaces, even though the temporal duration of these surfaces appears to be largely beyond the resolution of foraminiferal biostratigraphy. The Eocene/Oligocene contact is distinctively unconformable in several sections, with at least part of the Upper Eocene sediments missing. Chert nodules, common to abundant in most sections, are associated with deep‐ or cool‐water benthic assemblages (> 100–200 m and <15°C), indicating cool, nutrient‐rich bottom conditions probably influenced by the Antarctic Circumpolar Current beginning during the Early Oligocene. The mid‐Oligocene fall in sea‐level was probably coupled with a major local uplift that removed at least part of the Lower Oligocene, an event widely recorded in the Australian‐New Zealand region. In areas weakly affected, this glacioeustatic lowstand is represented by chert‐free limestone and grey to pink dolomites in some sections, with a poorly preserved assemblage comprising few planktonic and deep‐water benthic species. Local unconformities separate regional unconformity‐bounded or allostratigraphic packages of strata to represent third‐order sequences. Although variations in local subsidence might have influenced accumulation space and sediment thickness, glacioeustatic influence on the packaging of the sequences and units of the Gambier Limestone was easily the more effective and concordant with the global patterns.

Errata: An epeiric ramp: low-energy, cool-water carbonate facies in a Tertiary inland sea, Murray Basin, South Australia

Unfortunately, the quality of Figure 6 in this paper, which was published in volume 47, issue 4, on pp. 851–881, was affected during typesetting and printing. Please find the figure reproduced at a higher quality below. The publisher apologizes for this error. (a and b) Large foraminiferan–bryozoan facies. (a) Bioclastic grainstone. Fragmented bryozoans and clypeasterid echinoids with crab claws, coralline red algae and abundant large benthic foraminiferans (mostly Operculina and Amphistegina). Facies FB-1, Glenforslan Formation, Noll Road (section 14). Coin approximately 1 cm diameter. (b) Bryozoan rudstone pod, facies FB-2, Glenforslan Formation, Blanchetown (section 12). Coin is 1·5 cm in diameter. (c and d) Echinoid–bryozoan facies. (c) Echinoid–bryozoan floatstone facies (EB-4a) with abundant infaunal echinoids. Lower Mannum Formation, Devon Downs (section 5). Hammer head is approximately 15 cm in length. (d) Thalassinoides burrows (arrow) filled with echinoids (Lovenia, Monostychia, Eupatagus), pectinid bivalves and bryozoans. Facies EB-4b, upper Mannum Formation, Devon Downs (section 5). Coin is 1·5 cm in diameter.

Mineral Sands Occurrences in the Murray Basin, SoutheasternAustralia

The Murray Basin in southeastern Australia is proving to be a major mineral sand province that eventually will replace Australia’s east and west coasts in production of rutile, zircon, and ilmenite. Concentrations of relatively coarse-grained heavy mineral occur as beach placers in the Pliocene Loxton-Parilla sands in the upper part of the Murray Basin sequence. These formed as 400-km-long barrier complexes in the Murravian Gulf under the action of long-period ocean swell waves. We think the main source of barrier sand, at least initially, was from erosion of Miocene sands on the bed of the Murravian Gulf; progradation was a response to sea level fluctuations linked to Milankovitch climatic cycles in the Pliocene. In most areas, the resulting 400-km-wide barrier strand plain is now overlain by fluvial, aeolian, and lacustrine deposits. Typically, the heavy mineral deposits are ilmenite rich, with 30 to 40 percent rutile and zircon. They occur as single, or as multiple, stacked strandline deposits, are often more than 10 m thick, have mineral grades that exceed 20 percent in places, are several hundred meters wide and 10 to 25 km long; some contain up to several million tonnes of heavy mineral. The rutile and zircon are comparable in grain size and quality to minerals traditionally mined in Australia. Many of the deposits are associated with topographic ridges—the Neckarboo and Iona Ridges are the best known—that appear to be fault-bounded blocks. Deposits of major commercial significance found so far contain a total of over 12 million tonnes (Mt) of rutile, zircon, and ilmenite. The total, coarse-grained mineral sand resources in the Murray Basin are conservatively estimated to be over 50 Mt. The distribution of mineral sands in the Murray Basin seems to be associated with two aspects of the region’s geology and geomorphology: (1) a zone bordering the central part of the basin where the Pliocene barriers were derived from underlying Miocene sands that probably already contained some mineral concentrations and (2) growth faulting with deposits preferentially occurring on upfaulted blocks especially in the zone defined by (1) above. We speculate that localized uplift during the formation of the Loxton-Parilla barriers was sufficient to modify coastal processes on uplifted blocks so as to increase the rate of alongshore sediment bypass compared to nearby areas. This phenomenon has been simulated in computer modeling. Where the barrier sands were already enriched in heavy minerals, winnowing by storm waves formed beach placers on the uplifted fault-blocks. Based on criteria (1) and (2), the prospective areas of the Murray Basin account for 80 percent of the beach placers found to date.

An epeiric ramp: low‐energy, cool‐water carbonate facies in a Tertiary inland sea, Murray Basin, South Australia

The Murray Supergroup records temperate‐water carbonate deposition within a shallow, mesotrophic, Oligo‐Miocene inland sea protected from high‐energy waves and swells of the open ocean by a granitic archipelago at its southern margin. Rocks are very well preserved and exposed in nearly continuous outcrop along the River Murray in South Australia. Most facies are rich in carbonate silt, contain a background assemblage of gastropods (especially turritellids) and infaunal bivalves, and are packaged on a decimetre‐scale defined by firmground and hardground omission surfaces. Bioturbation is pervasive and overprinted, resulting in rare preservation of physical sedimentary structures. Facies are grouped into four associations (large foraminiferan–bryozoan, echinoid–bryozoan, mollusc and clay facies) interpreted to represent shallow‐water (&lt;50 m) deposition under progressively higher trophic resource levels (from low mesotrophy to eutrophy), and restricted marine conditions from relatively offshore to nearshore regions. A large‐scale shift from high‐ to low‐mesotrophic conditions within lower Miocene strata reflects a change in climate from wet to seasonally dry conditions and highlights the influence terrestrially derived nutrients had upon this shallow, land‐locked sea. Overall, low trophic resource levels during periods of seasonally dry climate resulted in a deepening of the euphotic zone, a widespread proliferation of foraminiferan photozoan fauna and a relatively high carbonate productivity. Inshore, heterozoan facies became progressively muddier and restricted towards the shoreline. In contrast, periods of wet climate led to rising trophic resource levels, resulting in a shallowing of the euphotic zone, a decrease in epifaunal and seagrass cover and widespread development of a mostly heterozoan biota dominated by infaunal echinoids. Rates of carbonate production and accumulation were relatively low. The Murray Basin is best described as an epeiric ramp. Wide facies belts developed in a shallow sea on a low‐angled slope reaching many hundreds of kilometres in length. Grainy shoal and back‐barrier facies were absent. Internally generated waves impinged the sea floor in offshore regions and, because of friction along a wide and shallow sea floor, created a low‐energy expanse of waters across the proximal ramp. Storms were the dominating depositional process capable of disrupting the entire sea floor.

Mineral Sands Occurrences in the Murray Basin, Southeastern Australia

Mineral Sands Occurrences in the Murray Basin, Southeastern Australia

Groundwater–lake interactions in semi-arid environments

A free-surface paleohydrologic model was developed along a cross-section across the Murray Basin in SE Australia to study the effects of groundwater flow on paleoclimate records in semi-arid environments, over millennial time scales. We demonstrate that the interaction between the groundwater table and regional topography is the primary factor controlling the location and timing of seepage fluxes within discharge zones. The groundwater system communicates regional effects between lake basins that are unconnected by surface water. This interaction can have a significant influence on the interpretation of paleoclimatic records, since lake–groundwater interactions are crucial to the formation of limnologic paleoclimatic indicators in arid environments.

Phylogeography of the Australian dunnart Sminthopsis crassicaudata (Marsupialia : Dasyuridae)

Analyses of mitochondrial DNA (mtDNA) and allozymes are used to investigate the population genetic structure, phylogeography and systematics of the fat-tailed dunnart, Sminthopsis crassicaudata. Phylogenetic analyses of control region sequences reveal the presence of two major mtDNA haplotype clades. A survey of the distribution of the two clades using diagnostic restriction endonucleases shows that one clade is restricted to southeast Australia whereas the second clade occupies the remaining central to western range of S. crassicaudata. Allozyme electrophoresis also shows concordant patterns of population structure, with significant differences in allele frequency at three loci between populations in the southeast and northwest. Together, the mtDNA and allozyme data provide evidence that S. crassicaudata consists of two Evolutionarily Significant Units (ESUs). The distribution of each ESU is not concordant with the distribution of the subspecies of S. crassicaudata, and we propose that the current subspecies classification neither reflects the major genetic subdivisions present within S. crassicaudata nor would be appropriate for any future conservation management. The level of divergence between mtDNA clades (3.4%) is indicative of cladogenesis in the Pleistocene and reflects a long-term barrier to maternal gene flow between these two populations. One potential historical barrier was Lake Bungunnia, which persisted in the Murray basin over much of the Pleistocene.

Palynostratigraphy of the murray basin, inland Southeastern Australia

To date, the only published comprehensive zonation for dating and correlating late Tertiary non‐marine sequences in Australia is that developed in the 1970s for the offshore Gippsland Basin on the extreme southeastern margin of the continent. In this paper an analogous zonation scheme is presented for the Murray Basin, a large intracratonic basin that covers some 300 000 km2 of inland New South Wales, Victoria and South Australia. Major spore and pollen sequences identified within this basin correspond with major periods of marine transgression‐regression, in the middle Eocene to early Oligocene, early Oligocene to middle Miocene and late Miocene to Pliocene. Presence/absence data allow the first two sequences to be subdivided into palynological zones that can be confidently correlated with zones established for the Gippsland Basin, viz., equivalents of the middle to late Eocene lower, middle and upper Nothofagidites asperus zones, and the Oligocene to middle Miocene Proteacidites tuberculatus and Canthiumidites bellus zones, respectively. Late Miocene‐early Pliocene and late Pliocene‐Pleistocene intervals are assigned to the Monotocidites galeatus Zone and Tubulifloridites pleistocenicus Zone, respectively. Changes in the relative abundance of commonly occurring species support the above subdivisions in a general way only and are not reliable as a basis for basin‐wide correlations. Until some independent geological or geophysical datum is found to allow a direct comparison of species time distributions across the basin, further formal subdivision of the zones is not recommended.

Discussion and Reply Lithostratigraphic revision and correlation of the Oligo‐Miocene Murray Supergroup, western Murray Basin, South Australia

Discussion and Reply Lithostratigraphic revision and correlation of the Oligo‐Miocene Murray Supergroup, western Murray Basin, South Australia

Tracing provenance through the isotope ages of littoral and sedimentary detrital zircon, eastern Australia

The provenance of detrital zircons in nineteen littoral and sedimentary deposits in eastern Australia is determined in terms of their isotopic ages measured by Sensitive High Resolution Ion MicroProbe (SHRIMP). Principal component analysis of the age data reveals four `age groupings' whose occurrence and distribution have wider implications for regional tectonics and general provenance studies. A 100–175 Ma age grouping is correlated with Jurassic/Cretaceous volcanism along the eastern Australian margin. A 225–350 Ma age grouping is correlated with the New England Orogen. A 350–500 Ma age grouping is correlated with magmatism in the Lachlan Orogen. The ultimate source of the Pacific–Gondwana 500–700 Ma age grouping is enigmatic, but is tentatively identified as a Neoproterozoic orogeny along the eastern Antarctic margin. The geochronology of detrital zircon reveals a strong regional variation along the eastern coast with the Lachlan Orogen age grouping stronger in the south, mixing with the 500–700 Ma age grouping in the central sector, and then a New England Orogen age grouping in the north. The Pacific–Gondwana age grouping on the central coast is derived from the Middle Triassic Hawkesbury Sandstone of the Sydney Basin. This distribution of the Pacific–Gondwana age grouping via the Sydney Basin is one example of how a favourable sedimentary pathway can have greater control over provenance than proximity. The other example occurs with Jurassic/Cretaceous age grains are prominent in the Murray Basin, around 1200 km from the protosource along the eastern margin, but not in sediments now accumulated on that same margin.

Growth and ground water uptake responses of lucerne to changes in groundwater levels and salinity: lysimeter, isotope and modelling studies

Shallow saline water tables underline large areas of the Riverine Plains of the Murray Basin of southern Australia. It is believed that deep-rooted perennial plants in these areas are able to reduce recharge and use shallow groundwater, thus controlling groundwater levels. Lysimeters represent the best experimental technique for investigating capillary upflow from shallow water tables and the associated processes of salt accumulation, plant water use, and growth response. Techniques involving stable isotopes of water help determine the components of upflow due to vegetation. When combined with models that stimulate salt and water movement in the soil zone and the plant water use and growth, we can thoroughly test our understanding of salinity processes and the ability of plants to control water tables. Results from WAVES simulations of plant growth, evapotranspiration, groundwater uptake, salt accumulation, and the impacts on lucerne growth are compared against measurements made in lysimeters at Griffith, NSW, Australia. With minimal calibration, WAVES was able to reproduce both the daily and seasonal variation in evapotranspiration, upward flux from the groundwater table, plant growth in terms of leaf area development, soil water profiles, soil water salinity, and root water extraction patterns. There was a decline of 36% in transpiration, 42% in leaf area growth, and 67% in upward flux after the salinity of the water table increased from 0.1 to 16 dS m −1. Although the upward flux of water was large, lucerne used little of it (< 20%), preferring `fresher' rainfall and irrigation water near the surface. Given the tests presented in this work, we think WAVES is applicable to irrigated agricultural systems.

Miocene foraminifera from the Finniss Clay and Cadell Marl, western Murray Basin: taxonomic and taphonomic contrasts and their environmental significance

Sandwiched between Miocene limestones of the Mannum Formation and Morgan Limestone in the western Murray Basin, the Finniss Clay and Cadell Marl contain different foraminiferal faunas with varying taphonomic grades. At the Mannum Pumping Station section, the Finniss Clay fauna has a low diversity, frequent shallow-water forms, and a poor taphonomic grade. In what was the deeper part of the basin at Waikerie, a diverse fauna with well-preserved small species is recorded in sediments equivalent to the Finniss Clay. In contrast, the Cadell Marl from various localities comprises a well-preserved and diverse biofacies with both shallow and deeper water taxa. These contrasts suggest different depositional environments: shallower and warm during deposition of the Finniss Clay and nutrient-rich, dysaerobic and deeper water during deposition of the Cadell Marl. The shallowing event indicated by faunas from the Finniss Clay was due to falling sea level close to the early/middle Miocene boundary, whereas the Cadell fauna appears to reflect the global carbon buildup at the peak of the Monterey carbon excursion during the Miocene climatic optimum, about 16 million years ago.

Lithostratigraphic revision and correlation of the Oligo‐Miocene Murray Supergroup, Western Murray Basin, South Australia

The Murray Basin in southeastern Australia is a large, shallow, intracratonic basin filled with laterally extensive, undeformed, Cenozoic carbonate and terrigenous clastic sedimentary rocks that constitute regional and locally important groundwater aquifers. The marine Oligo‐Miocene strata distributed throughout the southwestern portion of the basin are here encompassed within the Murray Supergroup. The Murray Supergroup (formerly Murray Group) incorporates the marginal marine marl and clay of the Ettrick Formation, Winnambool Formation and Geera Clay in the western and northern portions of the Murray Basin in South Australia, in addition to the limestone that outcrops along the banks of the River Murray in nearly continuous section for 175 km. The stratigraphic nomenclature of these rocks is revised as follows. The boundary between the lower and upper members of the Mannum Formation is redefined and a new Swan Reach Dolomite Member is erected. The Finniss Clay is revised to Finniss Formation possessing three new members: the Cowirra Clay Member, Portee Carbonate Member and Woolpunda Marl Member. The ‘Morgan Limestone’ is raised to Morgan Group and contains three new formations: the Glenforslan Formation, Cadell Formation (with Murbko Marl Member and Overland Corner Clay Member) and Bryant Creek Formation. The Pata Formation is redefined and described. Type and reference sections are erected for each new and revised unit, and are lithostratigraphically correlated to illustrate their stratigraphic architecture.

Evaluating sustainable groundwater management options using the MIKE SHE integrated hydrogeological modelling package

The Wakool Irrigation District consists of 74,000 ha of agricultural land, a large part of which is affected by a rising watertable. Irrigation in the district started in 1936 when the watertable depth was about 9 m. Over the past 30 years, the watertable has risen as a consequence of irrigation, wet winters and inadequate drainage. In addition, the Wakool Irrigation District is underlain by the Calivil and Renmark aquifers of the Murray Basin. Rising groundwater pressures in these deeper aquifers are also contributing to the rising shallow watertable. Since 1981, a sub-surface drainage scheme with 48 bores pumping shallow saline groundwater into a 2000 ha evaporation basin has been developed in two stages to control the watertable in the Wakool Irrigation District. This paper describes the development and application of an integrated hydrogeological model for the Wakool Irrigation District, where management of rising watertable levels and land salinisation is a continuing problem. The model development is considered to be an important part in the establishment of sustainable water management policies for the Wakool Irrigation District. The Wakool model was developed by using the MIKE SHE integrated catchment-modelling package. The developed model enables analysis of the complex hydrogeological regime in the region, and prediction of the environmental impacts of various management options. It is able to describe temporal and spatial variations in the exchange of water between the land surface, drainage and supply systems, and the aquifers within the area. Management options proposed in the Wakool Land and Water Management Plan have been analysed for the period between 1975 and 2020. Various scenarios such as the implementation of on-farm recycling ponds in conjunction with laser levelling, deep-rooted perennials, tree planting, installation of deep groundwater pumps and the effect of shallow groundwater pumping, were investigated. The results from these simulations indicate that the best option is the implementation of shallow pumping.

Willandra Lakes revisited: environmental framework for human occupation

AbstractThe story of the Willandra Lakes is also the story of those ancient people who lived there. The landforms, sediments and soils provide the environmental framework within which the patterns of human occupation must be interpreted. The original stratigraphic system involved just two units, the Mungo and Zanci. Two additional units are now defined; one incorporating complexities between Mungo and Zanci, the Arumpo Unit, and a second to acknowledge the reality of a lake full phase near 18ka cal., postdating Zanci aridity of the last glacial maximum. This new unit is defined from Lake Mulurulu as the Mulurulu Unit.Improved facies analysis from data involving lake sediments, freshwater quartz beach sands (QBSs) and lake‐dry pelletal clay dunes (PCDs) helps refine the sequence of environmental changes. Revision of radiocarbon chronologies with conversion to calendar years, and additional dates (radiocarbon, luminescence, amino acid racemisation) permit new age definitions of major environmental changes and human‐land interactions.Following a lake‐full phase (Lower Mungo time) from before about 55ka cal., a phase of PCD accumulation is dated to near 40ka cal. defining an early stage of hydrologic stress. Progressive water level oscillations continued (Arumpo time) culminating in major drying with deflation and extension of regional dune building over large areas of the Murray Basin near 20ka cal. (Zanci time). Freshwater returned temporarily to the Willandra lakes about 18–19ka cal.Throughout the period 25–19ka cal. spanning the glacial maximum, the apparent absence of fish and unionid mussels may reflect major temperature depression corresponding also to the period of maximum aridity. The ecological stress experienced at this time had an immense impact on the landscape, plants and especially larger animals, requiring new adaptive responses from human occupants. Early grinding techniques, pre‐dating evidence of seed grinding, are suggested.Reconstruction of the sedimentary sequence at the main archaeological site at Joulni reveals a pre‐Mungo unit deep in the sequence of a system developed by barrier construction isolating the Joulni Plain from the main lake. Analogous conditions at Lake Victoria today mirror development of the Joulni archaeological site. Oldest artefacts occurring within this un‐named unit are dated beyond 45ka cal.Human occupation on the lakeshore barrier system at Lake Mungo involved aquatic harvesting (fish and shellfish) associated with human burials before the onset of PCD deposition, pre‐40ka‐cal. The association here of the complex burial ritual (Mungo III) involving anointing with ochre at this time presents one of the dramatic mysteries of ancient human cultural development. In death, the story of that person illuminates our understanding of those ancient occupants and the Ice Age environments that supported them.

Alteration of Cenozoic cool-water carbonates to low-Mg calcite in marine waters, Gambier Embayment, South Australia

ABSTRACT The Oligo-Miocene Gambier Limestone is a poorly lithified, fine-grained, bryozoan-rich grainstone/wackestone and marl. Allochems in these rocks, which are typical of many modern and ancient cool-water carbonates, were originally calcite (LMC), Mg-calcite (IMC and HMC) and minor aragonite, but most are now neomorphosed to LMC. With the exception of calcretes, most limestones have < 5% cement, 13C and 18O values from 0 to +1.5o/oo, and preserved 87Sr/86Sr ratios that indicate that neomorphism occurred in seawater rather than meteoric or evolved pore waters. Marine diagenesis of the limestones was facilitated by their slow accumulation rates, which were ca. 15 mm/ky based on Sr-isotope stratigraphy, relatively fine grain size, and high porosities which locally reach 50%. The Sr and Mg contents of grainstones are significantly lower than in the original sediments, whereas a less porous marl has higher Sr and Mg contents. The grainstones have about 300 ppm Sr and 6000 ppm Mg, consistent with slow abiotic precipitation of calcite under near-equilibrium conditions with seawater, which is the thermodynamic drive for this diagenesis. The higher Sr and Mg content of the marl results from variable preservation of original allochems of biotic calcite. The results from this study and others on modern cool-water carbonates indicate that the extent of diagenesis varies with lithology, but much neomorphism occurred in seawater, with minimal effects from meteoric waters. As such, the chemical characteristics of seawater may be effectively preserved in some ancient cool-water carbonates.

Lessons from a case study of a geophysical interpretation in Western Victoria

This paper compares the predictions and results of the Victorian Initiative for Minerals and Petroleum drilling programme, mostly over the Horsham 1:250 000 map sheet area of western Victoria. Sixteen holes were drilled beneath thin cover of the Cainozoic Murray Basin at targets identified in Moore's (1996) geological interpretation of the airborne magnetic and ground based gravity data. This integrated interpretation divided the region into the Stawell and Glenelg Zones. The Stawell Zone metaturbidites and metabasalts form the eastern edge of the Lachlan Fold Belt. The Glenelg Zone included weakly metamorphosed andesites of the Dimboola Subzone, greenschist to amphibolite facies metaturbidites and metavolcanics of the Miga Subzone and amphibolite grade rocks of the Ozenkadnook Subzone. All were deformed in the 500 Ma Delamerian Orogeny.Drilling depths were estimated both from magnetic modelling and previous drilling in the region. Drilling targeted basement depths between 30 m and 250 m. Where magnetic modelling was the main depth control, basement depths were within 20% of predicted depths, slightly more reliable than those estimated from nearby drilling.Of the sixteen holes, nine intersected the predicted lithologies and another three intersected lithologies that substantially agreed with the predictions. While four drill holes intersected quite different lithologies to those predicted, no major geological reinterpretation was needed. The drilling intersected both Cambrian continental island arc volcanic rocks and Upper Proterozoic metasedimentary basement, strengthening the temporal and tectonic correlations between western Victoria and western Tasmania.The study showed that a careful interpretation can give a reliable indication of the basement, even in areas of total cover. Integrating geological and geophysical data and using standard geological logic and techniques, like drawing sections to test plan interpretations, are powerful aids. Drilling complemented the interpretation by providing samples that could be used to test the interpretive hypothesis.

Tertiary palynology: Beaupreaidites and new Conospermeae (Proteoideae) affiliates

Late Eocene proteaceous pollen assemblages of southern Australia containnumerous specimens of Conospermeae affiliation. As many of these aremorphologically confusing or nondescript, they have often been overlooked orgrouped within other fossil pollen species. In the western Eucla and MurrayBasins these fossil pollen types fall into two major categories: small speciesconventionally referred to unrelated New Zealand fossil taxa, and thoseincluded in Beaupreaidites elegansiformis Cookson 1950or Beaupreaidites spp. Integrated microscopy of singlefossil grains and a thorough investigation of extant Conospermeae pollen typesaided an investigation of the morphology and affiliations of these problematicgroups. Beaupreaidites elegansiformis was originallyillustrated by three dissimilar specimens, each from a different locality. Ofthese, two can be aligned with Beauprea Brongn. &amp; Gris., and the other, the former lectotype, is an extinct form unrelated toBeauprea. The diagnosis ofBeaupreaidites Cookson emend. Martin is amplified;B. elegansiformis is emended and its lectotypesuperseded; B. orbiculatus Dettmann &amp; Jarzen 1988 istransferred to Proteacidites; and five new species aredescribed (Beaupreaidites diversiformis,Proteacidites bireticulatus,P. carobelindiae, P. cirritulus,and P. marginatus).Proteacidites cirritulus can be positively aligned withpollen of the sclerophyllous genus Petrophile R.Br., inparticular with species now endemic to eastern Australia. The remainingProteacidites species, previously assigned toBeaupreaidites, were likely to have been shed by extinctproteaceous taxa closely allied to Petrophile. Therelative abundance of Petrophile-like pollen in thepalynofloras of the western Eucla and Murray Basins implies the presence ofsclerophyll communities akin to heath, woodland, and/or dry sclerophyllforests in coastal southern Australia during the Late Eocene. Fossilproteaceous genera are reviewed. The species referred here toProteacidites cannot be accommodated within any singlegenus as described in a recent revision of fossil proteaceous genera. Therehas long been quiet dissent among Australian Tertiary palynologists withrespect to revisions of fossil proteaceous genera and their subsequentinterpretation. Consensus, rather than individual determination and conflict,is overdue.

Chemical and isotopic indicators of point-source recharge to a karst aquifer, South Australia

Several hundred sinkholes, swamps and open drainage boreholes throughout the semi-arid to sub-humid areas of the southeast of South Australia are potential recharge sites to the upper part of the Gambier Limestone aquifer. This paper presents the results from a hydrochemical (Cl− and carbonate chemistry) and isotopic (δ2H, S 18O and 36Cl study used to estimate the importance of localised recharge from these point-source features to the karstic groundwater system. Results show that water recharging the groundwater via point-source features is detectable only on a local scale. Chemical and isotopic compositions of groundwaters more than 150 m from the larger of the point-source features are indistinguishable from regional groundwater compositions. Chloride concentrations, carbonate chemistry, and isotope data show that annual input of water via point sources contributes less than 10% of total recharge, with diffuse recharge providing the remainder to the study area as a whole. Point-source recharge is generally intermittent, and was observed to occur only for a few days at a time and only after a threshold of sustained rainfall had been exceeded (i.e. greater than 2.5 mm day−1 for more than 3 days).The stable isotopic composition of waters recharging via sinkholes tends to be enriched in 2H and 18O relative to regional groundwater and local precipitation. This is probably caused by a small degree of evaporation (less than 596 of water falling within the catchment) occurring during winter at high relative humidity (greater than 9596) before recharge. 36Cl from weapons testing is detectable in groundwaters near sinkholes and indicates significant retardation of Cl− within soils of the respective sub-drainage systems. Recharge has therefore occurred within the past 30 years, but cannot be quantified with any reliable precision from the 36Cl data.

New Data, New Insights: an Example from Western Victoria

The aeromagnetic surveys flown under the Victorian Initiative for Minerals and Petroleum and by others give a major regional dataset over western Victoria. This paper presents a new interpretation of the structural and tectonic history for the early Palaeozoic rocks of the region derived from integrating the aeromagnetic, regional mapping and other datasets. It provides a new geological model for exploration beneath the thin Murray Basin cover.Two distinct packages of rocks are present in the western Victorian basement; the eastern Stawell Zone and the western Glenelg Zone. The Stawell Zone contains turbidites and oceanic basalts typical of much of the Victorian Lachlan Fold Belt and which host major gold deposits. They are weakly magnetic with the basalts and pyrrhotitic slates providing most magnetic expression. Recent Ar-Ar dating gives a deformation age of about 435 Ma. Their western boundary is the northern extension of the Moyston Fault.A new tectonic framework is proposed for the Glenelg Zone. Island arc volcanic rocks and metasediments of the Zone have been variably metamorphosed and simply deformed in the 500 Ma Delamerian Orogeny. The rocks lie in a similar structural and tectonic position to those of the Mount Read Volcanics and have potential for VHMS deposits. Correlations can also be made with other Cambrian VHMS deposits and prospective regions in eastern Australia.Along the South Australian border part of the Glenelg Zone, the Ozenkadnook Subzone, contains amphibolite grade rocks that have been complexly folded in a deformation that seems to be earlier than the Delamerian. These rocks are of uncertain affinity, but may be a northern correlative of the upper Proterozoic rocks seen in northwestern Tasmania.Keywords: