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A 4 m long core taken from the freshwater Blue Lake crater near the township of Mount Gambier in southeastern South Australia provided a high-resolution palaeoclimatic record for the last six millennia. Accelerator Mass Spectrometry (AMS) radiocarbon ( 14 C) dates were obtained from organic plant fibres and biogenic carbonates from the laminated sequence of the core and from a modern water sample. Large discrepancies between the radiocarbon ages determined from plant fibres and biogenic carbonates indicate the presence of a time-variable lacustrine reservoir, which is consistent with what is known of the lake's hydrology. Ostracod assemblages, associated with stable isotope (δ 13 C, δ 18 O) analyses and, in combination with Mg/Ca, Sr/Ca and Na/Ca analyses done on ostracod valves, infer salinity, temperature and water level changes in Blue Lake over the last 6 millenia. The influence of local aquifers through time has also been determined from the Na/Ca of ostracod valves. Approximately 900 year cycles are evident in the δ 13 C record from 5.4 ka to 1.8 ka. The history of Blue Lake records an initial period of high hydrological variability around 6 ka, becoming increasingly deeper as groundwater flowed into the basin. By 4 ka, the lake had reached steady state with the lake level fluctuating by as much as 9 m, although significant geochemical variations represent temperature fluctuations until European settlement near the lake in 1839.

The partition coeffi cients (K D ) guiding the uptake of Mg and Sr in the low-Mg calcite valves of ostracodes in Australian saline lakes have been reviewed in line with new information on the bicarbonate content and the ! Mg/! Ca of the ambient waters. Strongly alkaline and very high ! Mg/! Ca (>>20) waters cause the partition coeffi cients of ostracodes to differ signifi cantly from those found in other lakes with lower ! Mg/! Ca values. Water salinity does not affect the uptake of Mg or Sr in ostracode valves, whereas the ! HCO 3 ‐ of the water strongly correlates to K D [Sr], with high ! HCO 3 ‐ resulting in a signifi

Systematic analysis of Pb, Sr and Nd isotopes of 32 fluvial clay samples ( 6 km 2 ) Murray Darling Basin (MDB), located in semiarid southeastern Australia, displays similar isotopic values between some MDB clays and dust from several ice core samples from the EPICA Dome C in Antarctica. Close scrutiny of several ratios of the four Pb isotopes, and in particular 208 Pb/ 207 Pb versus 206 Pb/ 207 Pb, shows that several samples from the Darling-sub-basin of the MDB display similar values for the same isotopes for Dome C samples from different ages, and more particularly during wet phases in Australia [Marine Isotopic Stages 5e, 3 and 1]. The combination of Nd and Sr isotopic ratios from the same MDB fluvial clays clearly eliminates the Murray sub-basin, and supports the Darling sub-basin as a potential source of aeolian material to Antarctica. Overall, the Australian dust supply to Antarctica predominantly occurred during interglacial periods. The work presented here shows that aerosols generated in southeastern Australia can travel to parts of West Antarctica and this is supported by atmospheric observations and models. In addition, evidence of Australian dust in Antarctic ice cores further implies dust deposition in the Southern Ocean would have occurred in the past. Current meteorological observations also imply that the western Pacific and Indian Ocean sector of the Southern Ocean would frequently receive aeolian dust components originating from southeastern Australia.

a b s t r a c t To understand Holocene climatic development and to determine drivers of climatic changes and climate variability, high-resolution marine proxy records are required from key oceanic locations. However, information on the Holocene climate development from the Southern Hemisphere is still rare and mainly based on terrestrial archives. Here, we present data with a high-resolution of circa 35 years from sediment cores taken east of the Great Australian Bight, where it is possible to determine Southern Ocean Holocene climate and the longer-term trends of the El Nino-Southern Oscillation (ENSO) conditions. For this purpose, we used the oxygen-isotope records of two planktonic foraminifer species Globigerinoides ruber and Globigerina bulloides which inhabit different water masses as well as faunal counts of plank- tonic foraminifers. After the ocean frontal systems off southern Australia were pushed northward by orbitally-forced insolation changes during the early Holocene, the data indicate increasing ENSO variability during the mid to late Holocene when the fronts shifted polewards again. A strong circa 1550 year cycle is found in the Globigerina bulloides record which reflects the wider Southern Ocean signal with prominent cold phases centred at circa 9.2, 7.3, 5.8, 4.3, 2.7, 1.4 ka BP and, possibly the Little Ice Age, which have global counterparts.

The shallow seas surrounding Northern Australia, far away from former ice sheets and on a tectonically stable margin, is ideally suited for sea-level reconstructions as hydro-isostatic effects there are minimal. Detailed examination of ostracod and foraminifer remains, recovered from gravity core RS176/GC 5 from Bonaparte Gulf, and which is located at 118 m water depth, provides a detailed history of sea-level transgression coinciding with the end of Last Glacial Maximum [LGM]. For the period spanning ~ 30,000 to 20,100 cal years BP, the paucity of sediment may represent some erosion, but there is no sign of pedogenesis for that interval in the core. After 20,100 cal years BP, estuarine conditions prevailed at the site, followed by an obvious sea level rise at 19,400 years BP that is well constrained by 14C dates and high sedimentation. The evidence of a sea-level rise after 19,400 cal years BP of the order of 10 m is based on observations made on microfossil remains. Higher in the core, the presence of aragonitic pteropods is a clear indication of open marine conditions because they could not have been reworked, due to their fragility.

article Comparisons of ambient bottom-water geochemistry and stable isotopic values of the tests of living (stained) calcareous benthic foraminifera from the North Pacific (on the Aleutian Margin, water depth 1988 m) and Murray Canyons group in the Southern Indian Ocean (Australian Margin, water depths 2476 m and 1634 m) provide modern environmental analogs to calibrate paleoenvironmental assessments. Consistent with the hypothesis that microhabitat preferences influence foraminiferal isotopic values, benthic foraminifera from both margins were depleted in 13 C with respect to bottom-water dissolved inorganic carbon (DIC). The carbon isotope values of deep infaunal foraminifera (Chilostomella oolina, Globobulimina pacifica) showed greater differences from estimates of those of DIC than shallow benthic foraminifera (Bulimina mexicana, Bolivinita quadrilatera, Pullenia bulloides). This study provides new isotopic and ecological information for B. quadrilatera. The mean Δδ 13 C value, defined as foraminiferal δ 13 C values minus estimated ambient δ 13 C values from the Aleutian Margin, is 0.97‰ higher for G. pacifica than the mean from the Murray Canyon. This difference may result either from genetic or biological differences between the populations or from differences in environmental isotopic influences (such as pore water differences) that were not accounted for in the equilibrium calculations. These analyses provide calibration information for the evaluation of bottom water conditions and circulation patterns of ancient oceans based on fossil foraminiferal geochemistry.

ARTICLE I NFO We have examined the upper 276 cm of deep-sea core BAR9403 taken at a water depth of 2034 m offshore the southern portion of Sumatra in the eastern Indian Ocean using several micropalaeontological proxies. Faunal counts and stable isotopes of oxygen and carbon of planktic and benthic foraminifers, as well as floral counts of dinoflagellates were obtained to reconstruct conditions in the oceans over the last 35,000 years. At times, we found that when benthic foraminifers indicate high organic content values at the bottom of the ocean this is not paralleled by high productivity signals at the sea surface, but instead must relate to changes in bottom-water circulation as a result of slower water circulation. The marine isotopic stages (MIS) 3-1 are clearly differentiated by benthic and foraminiferal assemblages as well as dinoflagellates and their cysts. MIS 3 is characterised by a much sharper (than today) thermocline that was closer to the sea surface and by the absence of a low-salinity 'barrier layer' which today results from high monsoonal rains. The absence of the latter persisted during the last glacial period (MIS 2) when bottom circulation must have been reduced and high percentages of organic matter occurred on the sea floor combined with low dissolved-oxygen levels. The deglaciation is marked by a change in salinity at the sea surface as seen by the dinoflagellates and planktic foraminifers and progressive alteration of the thermocline was detected by foraminifers suggesting a less productive deep chlorophyll maximum in contrast with MIS 3 and 2. Monsoonal activity commenced around 15,000 cal years ago and was well established 2000 years later. The Holocene is marked by a significant increase in river discharge to the ocean, pulsed by the delivery of organic matter to the sea floor, despite overall oligotrophic conditions at and near the sea surface induced by a permanent low-salinity cap. We did not identify obvious and persistent upwelling conditions offshore Sumatra for the last 35,000 years.

Cluster analysis and species abundance plots of radiolarian abundance counts from core tops from the eastern Indian Ocean between 12° S and 31° S, and the southern Indian Ocean between 31° S and 62.5° S, demonstrate the existence of environmentallyrelated provinces supporting distinct taxa assemblages. These provinces are closely associated with currents in the eastern sector of the Indian Ocean and with fronts in the southern sector. The radiolarian assemblages correlate strongly with salinity-normalised total alkalinity (NTA) at the sea-surface, with temperature, salinity, and density from the sea-surface to 300 m, and with dissolved oxygen and nitrate and phosphate concentrations from the sea-surface to 100 m. Palaeo-reconstructions of these parameters at the sea-surface have been made for six Last Glacial Maximum (LGM) samples from five eastern Indian Ocean cores. The LGM sea-surface temperature estimates are comparable with those based on planktonic foraminiferal counts of the same samples obtained by other researchers. The reconstructions show that, since the LGM, density increased markedly along the Western Australian coast south of 20° S but changed little further from the Western Australian coast. By contrast, phosphate concentrations were marginally lower than modern values along the Western Australian coast south of 20° S but more than twice modern values in the other LGM samples. The utility of various regression and calibration techniques is discussed. It is concluded that, probably due to the effects of differences in radiolarian habitat, ocean currents, and/or environmental gradients, only one method, weighted averaging — partial least squares, is reliable in a study area of this size and complexity. If other methods are to be used, the study area must be partitioned into at least two separate regions with the major split between the eastern and southern sectors of the Indian Ocean. © 2007 Elsevier B.V. All rights reserved.

As the climate warmed at the end of the last glacial period, a rapid reversal in temperature, the Younger Dryas (YD) event, briefly returned much of the North Atlantic region to near full-glacial conditions. The event was associated with climate reversals in many other areas of the Northern Hemisphere and also with warming over and near Antarctica. However, the expression of the YD in the mid- to low latitudes of the Southern Hemisphere (and the southwest Pacific region in particular) is much more controversial. Here we show that the Waiho Loop advance of the Franz Josef Glacier in New Zealand was not a YD event, as previously thought, and that the adjacent ocean warmed throughout the YD.

An attempt has been made at a comprehensive study of the diversity and distribution of subterranean ostracods in the Pilbara region, northwestern Australia. The area is a “hot spot” for subterranean biodiversity, some of which is currently under threat from extensive mining operations. Both bore and well sites were targeted, totalling 445 sites, to obtain a thorough coverage of the 200,000 km2. In addition, physical and hydrochemical measurements were obtained for all of the samples (temperature, conductivity, dissolved oxygen, pH, Eh, turbidity, nutrients, major ions). Ostracods were retrieved from approximately 47% of the samples and 56% of the sites. Twenty-one genera and around 110 species of ostracods have been identified. Of these, 72 are new species and a further 10 are currently in open nomenclature, due to the lack of suitable material for formal taxonomic description. The Candoninae are particularly well represented with 12 genera; some, such as Areacandona and Deminutiocandona, with 25 and 10 species respectively. Most sites (80%) were dominated by only one or two species, with up to six species at some sites. Population density varied from 1–370 individuals/sample. The most abundant and diverse sites occur in fresh, bicarbonate-rich aquifers utilised for water extraction, such as Pannawonica (Robe River), Cane River and Millstream. There is a clear distinction between taxa at the genus level from coastal and low-lying alluvial sites, and upland sites (>300 m altitude). Beyond this, the majority of species are confined within a surface water catchment, or in many cases, a specific aquifer. There are, however, some morphological similarities of the carapaces between different species within similar hydrogeologic settings. Ornate and ridged-valved species are common in the Mg-HCO3 waters of the Newman and Marillana Creek areas, whereas smooth-shelled, tapered forms are prevalent in alluvial aquifers. The more saline, Na-Cl rich aquifers at the edge of Great Sandy Desert have a particularly distinctive fauna, including one almost triangular species. The distribution of the stygobitic ostracod species in relation to the hydrogeology and water chemistry is discussed.

Throughout the last glacial cycle, the region between Australia and New Guinea, which is today known as the Gulf of Carpentaria, has oscillated from open shallow marine conditions to a large, land-locked freshwater lake, including periods of subaerial exposure. Ostracod faunal assemblages and variations in the valve morphology, preserved in the sediments of the gulf, record these changes. A 14.8 m long core (MD972132) extracted from near the centre of the modern Gulf of Carpentaria, spanning the last 130 ka BP provides the basis of this study. Environmental facies were determined by R- and Q-mode cluster analysis of the ostracod assemblage data, including 72 species, and comparison with modern analogues from both the Gulf of Carpentaria and Southeast Asian region. Using these methods, six clearly distinct biofacies were identified: (i) open shallow marine facies, including bairdiids, pectocytherinids and cytherettids; (ii) shallow marine facies, dominated by Cytherella and Hemikrithe; (iii) marginal marine facies, including Xestoleberis and Praemunita; (iv) tidal channel facies, dominated by Loxoconcha; (v) estuarine assemblage, comprising Venericythere and Leptocythere; (vi) non-marine facies a. brackish lagoon/lake facies dominated by Cyprideis and Leptocythere; b. freshwater facies, including Ilyocypris, with Cyprinotus and Cypretta. In addition, morphological variation of valves of the more “plastic” species, in particular Cyprideis australiensis and Leptocythere hartmanni, was observed and related to environmental variables, including salinity and solute composition. These two species occur through more than half of the length of the core and show significant variability. C. australiensis with irregularshaped sieve pores is associated with heavily reticulated valves of L. hartmanni, around 90–70 ka BP, indicating increased salinity and carbonate-limited environments. Conversely, C. australiensis with round sieve pores occurs with finely reticulated valves of L. hartmanni from around 50 ka BP, in fresher, carbonate-rich environments. The preservation of valves was also noted so as to infer post-depositional effects, revealing shoreline features, channel activity and subaerial exposure. Combined ostracod biofacies and morphological analysis reveals a fluctuating marine environment through Marine Isotope Stage (MIS) 5, terminating in a restricted lagoon around 90 ka BP, followed by an extensive period of subaerial exposure in this

Benthic foraminifera and carbon isotopes from closely spaced samples taken from three deep-sea cores were analysed to reconstruct the palaeoceanographic evolution of the eastern Indian Ocean for the last 30 kyrs, with an extension back to 60 kyrs based on one core. Benthic foraminifera were studied by means of Q-mode Factor Analysis. The benthic foraminifera accumulation rate (BFAR) and the accumulation rates (AR) of Bulimina aculeata, Epistominella exigua and Uvigerina proboscidea were calculated for determining episodes of increased organic matter supply to the sea floor. The δ 18 O and δ 13 C records of Cibicidoides wuellerstorfi

The terrigenous component of deep-sea sediment core MD03-2611, offshore South Australia, has been examined for mineralogical, geochemical and isotopic tracers to reconstruct the deglacial and Holocene climate on the adjacent southeastern Australian continent. The provenance of the terrigenous component is constrained by using a combination of clay minerals, conservative elements like rare earths (REEs) and Sr- and Nd isotopic ratios. From 17 to 5 ka BP, the sediment signature is dominated byalluvialsedimentsfromtheMurray–DarlingBasin(MDB).Startingat8kaandculminatingfrom5katothepresent,enrichmentof REEs and kaolinite content, increasing grain size, high 87 Sr/ 86 Sr ratios and strongly negative eNd(0) values are attributed to an influx of aeolian dust, probably sourced from older crustal terranes in central and/or western Australia, although the exact provenance of the dust could not be assessed. The input of fluvial material from a common MDB source ceased at 13.5 ka BP, but 2 periods of increased fluvial input, originating mainly in the Murray catchment, are indicated by clay contents, K and Rb concentrations, and Sr and Nd isotope ratios. These fluvial pulses probably reflect periods of increased rainfall in southeastern Australia. The first fluvial pulse from 13.5 to 11.5 ka had not been recorded in the region previously, while the second pulse from 9.5 to 7.5 ka BP corresponds to periods of increased rainfall already documented in records from 2 lakes in the region. The supply of fluvial versus aeolian material in core MD03-2611 mirrors patterns of humidity and aridity inferred from other continental records in SE Australia, although our study provides information for the Late Pleistocene/Holocene transition not recorded elsewhere. © 2007 Elsevier B.V. All rights reserved.

Pollen recovered from core tops of deep-sea cores from offshore northwestern Western Australia were used to build climatic transfer functions applied to sediment samples from major rivers bordering the ocean in the same region and a deep-sea core offshore Northwest Cape. Results show for the last 100 000 years, with a gap in the record spanning the 64 000 to 46 000 years interval, that from about 100 000 to 82 000 yr BP, climatic conditions represented by rainfall, temperature and number of humid months, were significantly higher than today's values. For the entire record, the coldest period occurred about 43 000 to 39 000 yr BP but it was wetter than today, whereas the Last Glacial Maximum saw a significant reduction in summer rainfall, interpreted as a result of the absence of monsoonal activity in the region. The Holocene can be divided into two distinct phases: one peaking around 6000 cal. yr BP with highest rainfall and summer temperatures; the second one commencing at 5000 cal. yr BP and showing a progressive decrease in summer rainfall in contrast to an increase in winter rainfall, paralleled by a progressive decrease in temperatures. Copyright 2006 John Wiley & Sons, Ltd.

This paper details the Late Quaternary palaeoceanography of the Banda Sea based on analysis of core SHI 9016, located east of Timor. This core is located below the pathway of the Indonesian Throughflow, at a depth of 1805 m bsl. Planktonic foraminifera assemblages, the d 18 O and d 13 C of the foraminifer Globigerinoides ruber, and the total carbonate content of each

Relative abundances of benthic foraminifera in 57 core tops collected within a depth-range between 700 and 4335 m below sea level [b.s.l.] from the eastern Indian Ocean (mostly between Australia and Indonesia) were investigated quantitatively using Detrended Correspondence Analysis (DCA) to analyse species spatial-distribution. Canonical Correspondence Analysis (CCA) and correlation matrices were used to evaluate the relationships between the species distribution and environmental variables (temperature, salinity, dissolved oxygen, nitrate and phosphate concentrations, carbon-flux rate). Seven key-species proved useful for distinguishing environmental parameters. Two groups of species are identified by means of the first DCA ordination axis. The first group increases in relative abundances with depth and includes three taxa: Oridorsalis tener umbonatus, Epistominella exigua and Pyrgo murrhina. These three taxa prefer a cold ( 3.5 ml/l) environment, with low carbon flux to the sea floor ( 2.5 °C) environment characterised by high carbon-flux rate (> 2.5 g C m− 2 year− 1). N. irregularis is associated with high dissolved-oxygen concentrations (> 3 ml/l) and its distribution is limited to south of 20 °S. In this area, the contemporary presence of the low salinity and well oxygenated Antarctic Intermediate Water and low primary productivity at the sea-surface (which causes low oxygen consumption at the sea floor) create the ideal conditions for this species. The second ordination-axis scores identify another taxon, Uvigerina proboscidea. The distribution of this species is mainly limited to low latitudes (north of 25°S), where carbon flux rate is high (> 3.5 g C m− 2 year− 1), due to higher primary productivity levels at the sea surface, and oxygen levels are low (

Two sediment cores from the Murray Canyons area, south of Kangaroo Island, South Australia, were investigated for proxy-records to reconstruct past productivity of the surface waters in the area over the last 175 ka. The proxies used included concentrations of aragonite, low- and high-Mg calcite, total carbonate, total organic carbon, sulfur and δ13C of Globigerina bulloides. Cyclic increases in palaeoproductivity were observed to be in tune with insolation minima at 30°S. The atmospheric conditions during insolation minima were comparable to present winter patterns, when strong westerly winds dominate over the area and bring dust from the central desert areas. During the last insolation minimum (last glacial maximum: LGM), the Murray Canyons laid directly under the “Eastern Australian Dust Plume”. Dust could have fertilized surface waters and initiated the observed productivity “increases” on a precessional time scale. The core from the more westerly canyons is richer in organic matter; this could be attributed to the influx of organic matter from shallower water, which is carried by an overflow of hypersaline water from the Spencer Gulf to the deep ocean, using the western canyons as conduits. There is no evidence that the “Palaeo-Murray River”, which debouches close to the core sites during sealevel lowstands, was a major source of nutrients for surface waters. Although total carbonate concentrations remained high, planktonic foraminifers were fewer in numbers during these periods, possibly due to reduced light penetration caused by suspended river material. A deglacial minimum in δ13C of Globigerina bulloides, observed in other cores from the southern hemisphere and attributed to a major hydrographic change south of the Polar Front, is also visible in our two cores, thus attesting to the global significance of the event.

The Scottiinae, thus far comprising the genera Scottia and Mesocypris, form an important lineage of (semi-) terrestrial ostracods within the family Cyprididae. Scottia has a mainly Holarctic distribution, while Mesocypris was thus far known from Australia (including Tasmania) and Africa (including Madagascar). Detailed description of a new species from Australia and subsequent cladistic analysis of the Scottiinae as a whole, based on morphological characteristics, showed that the two geographically separated clusters of Mesocypris s.l. actually belong in two genera. The most derived Australian clade requires the erection of a new genus. Austromesocypris n.gen., and its type species, A. berentsae n.sp. are here described. Austromesocypris n.gen. and Mesocypris s.s. are lodged in the tribe Mesocypridini, previously a subfamily synonymised with Scottiinae, but here re-instated with a change of rank, while Scottia is in the nominate tribe Scottiini. Various morphological transformation series are present in the Mesocypridini, i.e. progressive loss of natatory setae on A2 and fusion of segments on A1. The latter transformation is a reversal to aspects of juvenile morphologies through heterochronic processes. Analysis of all aspects of the A1 chaetotaxy, by comparison to an ontogenetic sequence of another cypridinid, shows that evolution of different characters (e.g. segment fusion and number and position of setae) has occurred independently. The distribution of the Scottiinae in the southern Hemisphere is briefly discussed in light of past continental distributions.

Two sediment cores from the deep-sea Murray Canyons area, south of Kangaroo Island, Australia were investigated for quantity and composition of terrigenous material. Spanning the last 175 ka, terrigenous matter from these cores provides evidence for changes in sea level and palaeoclimate of the adjacent Australian continent. Located offshore Australia's major river system, the Murray–Darling, the sediment cores record varying inputs of suspended river clays. High input prevails during glacial periods, when sea level is low and the river discharges directly at the edge of the continental shelf. Today, and during previous periods of high sea level, the Mouth of the River Murray is more than 200 km away from the core sites, sedimentation of terrigenous matter is reduced and consists primarily of aeolian dust. However, even during periods of high sea level in the early Holocene (11–6 ka), river clays reached the core site, indicating a stronger discharge from the Murray and more humid conditions in the catchment area. The present mode of low-input aeolian sedimentation over the core sites was only established 4 ka ago. Differences in composition of the river clays between the penultimate glacial (isotope stage 6) and the last glacial maximum (isotope stage 2; LGM), as well as different clay mineral assemblages between the two cores during the LGM suggest that palaeodrainage on the exposed shelf varied between sea level lowstands. Minute changes in shelf morphology could have prevented the “Palaeo-River Vincent”, a river which drained the glacially dry Gulf St. Vincent, from joining the course of the Murray during the LGM. Clay mineral evidence suggests that this palaeo-river did join the Murray during the penultimate glacial and significantly altered the clay mineral signature from the Murray–Darling catchment area.

The Mg/Ca composition of calcium carbonate tests (shells) secreted by planktonic foraminifera is increasingly being employed to estimate past seawater temperatures and reconstruct paleocean and climate records spanning hundreds of thousands of years. We show, using two high-resolution microanalysis techniques, that the final chamber of the planktonic foraminifera Orbulina universa typically comprises between three and six paired, low and high Mg, growth bands. The number and spacing of these bands is consistent with a diurnal origin, modulated by changing pH within the foraminiferal microenvironment due to the day-night, photosynthesis-respiration cycle of algal symbionts. The amplitude of Mg/Ca variation within individual tests and across many daily growth bands cannot be accounted for by seawater temperature in the shallow, euphotic zone habitat of O. universa. Our results indicate the Mg/Ca composition of calcite precipitated by O. universa in nature is strongly influenced by diurnal changes in the biological activity of algal symbionts and the host foraminifer. This brings into question the fundamental premise often made in applying Mg/Ca palaeoseawater thermometry, that the Mg/Ca composition of foraminiferal calcite is determined by seawater temperature, and whether the Mg/Ca composition of other planktonic species that are more widely used for palaeoseawater thermometry are subject to similar influences. © 2004 Elsevier B.V. All rights reserved.

Significant variations in the Sr/Ca in waters from the eastern Indian Ocean in the vicinity of Australia, both from the surface and from shallow depth profiles, are documented. The strontium sulfate-secreting protozoans Acantharia, which are common in the upper 400 m of the oceans, especially at low latitudes, contribute substantially to changes in the Sr/Ca of oceanic waters by extracting Sr for the formation of their skeletons. Below such depths, these organisms dissolve and the Sr/Ca of seawater regains its ‘conservative’ nature. This mechanism accounts for some of the variability of the Sr/Ca near the surface of the ocean, but this may still be found at depth as surface waters become entrained at greater depths. It is argued here that the noted Sr/Ca variations may explain discrepancies between coral data sets from different parts of the oceans, and calls for caution when reconstructing sea-surface temperatures from the Sr/Ca of corals.

The shell chemistry of ostracodes is a useful indicator of past environmental conditions especially when the chemistry data are considered along with other proxy data. The complexities involved with the chemical and isotopic changes accompanying hydrologic change, solute evolution, and the autoecology of ostracodes all point to the need to exercise caution when interpreting shell chemistry. Nevertheless, the stable-isotope values and cation ratios (e.g., Mg/Ca, Sr/Ca) as well as the species assemblage of ostracodes can provide powerful tools for the reconstruction of paleoclimate and paleohydrology. In particular, the changes in Mg/Ca and Sr/Ca of well-calcified ostracodes shells record the qualitative changes in solute composition, and when the dissolved Mg/Ca remains relatively constant, the Mg/Ca in the ostracode shell is proportional to water temperature.

The nature of compositional variability within the tiny calcitic shells (tests) that are precipitated by planktonic foraminifera has been investigated using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Systematic large and correlated variation of Mg/Ca, Mn/Ca, Ba/Ca and Zn/Ca but relatively uniform Sr/Ca are observed through the test walls of analysed species (Globigerinoides sacculifer, Globigerinoides ruber, Neogloboquadrina pachyderma and Neogloboquadrina dutertrei). Distinct chamber and chamber-wall layer compositions can be resolved within individual tests, and Mg/Ca compositional differences observed in sequentially precipitated test components of the different species analysed are consistent with seawater temperature changes occurring with habitat migration during their adult life-cycle stages. Estimated test calcification temperatures are in keeping with available seawater temperature constraints, indicating the potential for accurate seawater temperature reconstruction using LA-ICP-MS. Mg-rich (

The 1st International Symposium on Ostracoda (ISO) was held in Naples (1963). The philosophy behind this symposium and the logical outcome of what is now known as the International Research Group on Ostracoda (IRGO) are here reviewed, namely ostracodology over the last 50 years is sociologically analysed. Three different and important historic moments for the scientific achievements of this domain are recognised. The first one, between about 1963 and 1983, is related to applied research for the oil industry as well as to the great interest in the better description of the marine environment by both zoologists and palaeontologists. Another important aspect during this period was the work by researchers dealing with Palaeozoic ostracods, who had their own discussion group, IRGPO. Gradually, the merger of this latter group with those dealing with post-Palaeozoic ostracods at various meetings improved the communication between the two groups of specialists. A second period was approximately delineated between 1983 and 2003. During this time-slice, more emphasis was addressed to environmental research with topics such as the study of global events and long-term climate change. Ostracodologists profited also from the research “politics” within national and international programmes. Large international research teams emerged using new research methods. During the third period (2003–2013), communication and collaborative research reached a global dimension. Amongst the topics of research we cite the reconstruction of palaeoclimate using transfer functions, the building of large datasets of ostracod distributions for regional and intercontinental studies, and the implementation of actions that should lead to taxonomic harmonisation. Projects within which molecular biological techniques are routinely used, combined with sophisticated morphological information, expanded now in their importance. The documentation of the ostracod description improved through new techniques to visualise morphological details, which stimulated also communication between ostracodologists. Efforts of making available ostracod information through newsletters and electronic media are evoked.

A sediment core located below the present South Java Current (SJC) was used to reconstruct paleoclimate and paleoceanography on the basis of biogenic and terrigenic proxy-records. The core spans the past 80 ka of environmental change and shows considerable contrasts from the glacial to the Holocene. Presently, the core site is situated beneath a seasonally varying low-salinity tongue which is advected from the Java Sea via the Sunda Strait. It carries terrigenous matter of a characteristic signature. During the last glacial period (stage 4-2), when sea level was lower than during the Holocene, the Sunda Strait was closed and the terrigenous supply from that source ceased. As the core site is close to the equator, our results indicate that atmospheric and oceanographic circulation was alternatively dominated by the Northern Hemisphere East Asian Monsoon system and the Southern Hemisphere Australian Monsoon system. Between 20 and 12 ka, the (Australian) SE Winter Monsoon reached its maximum and intensified the westward flowing SJC. Increased mixing of the surface waters led to a slight rise in paleoproductivity. A similar but much weaker situation prevailed from 74 to 70 ka. During most of the glacial period, from 70 to 20 ka, strong northeasterly winds associated with the East Asian Winter Monsoon intensified the Indian Monsoon Current and the eastward flowing SJC, and may have also carried dust across the equator to our core site. During this glacial phase, populations of the giant diatom Ethmodiscus rex were thriving and may indicate a reduced deep and intermediate thermohaline circulation at the site. The monsoonal system as we know it today, with distinct dry and wet seasons, may not have been active before V12 ka. : 2002 Elsevier Science B.V. All rights reserved.

Environmental changes recognised in a 80-ka record obtained from a deep-sea core taken at a water depth of 2542 m offshore southeast Sumatra conclusively indicate, for the first time, that ‘blooms’ of the giant diatom Ethmodiscus rex occurred in the Indian Ocean during the last glacial period, with the largest numbers coinciding with the Last Glacial Maximum. Previous occurrences of E. rex in both the Indian and the western Pacific Oceans could not be dated due to the paucity of foraminifers and contamination by diagenetic carbonate found in association with the diatoms. We use a reliable N 18 O record to date the core. The interpretation of terrigenous clays and trace metals in the core sediments, together with carbon isotopes measured on planktic foraminifers, suggests that conditions that favoured the diatomaceous blooms were a combination of changes in hydrological regime in the region caused by a substantial increase in salinity near the surface, and coinciding with a rise in nitrate levels near the surface. No major upwelling was recorded during glacial times. During the glacial period, the Indonesian Archipelago, as other tropical regions, was much drier, thus preventing a low-salinity ‘cap’ to occur at the surface of the oceans in contrast with the Holocene. In addition, monsoonal winds were absent, thus permitting the ocean to be permanently stratified, with high levels of silica and nutrients near the surface. The glacial mode of productivity, represented by the ‘blooms’ of E. rex added considerable amounts of biogenic silica to the sediment, but is not reflected by ‘classic’ productivity proxies like biogenic barium. Therefore, we have to distinguish between a ‘classic’ productivity mode as observed in the photic zone today and a glacial ‘deep’ productivity, dominated by E. rex, which may have utilised nutrients from a wider depth range. 9 2002 Elsevier Science B.V. All rights reserved.

A radiocarbon-dated core, NC, taken in the alpine Blue Lake in the Snowy Mountains of southeastern Australia provides a Holocene record of sedimentation that consists mainly of organic clays. Two types of quartz grains are recovered from 81 samples from the core. One type consists of angular grains, with frequently shattered faces, which originates from granitic lithologies present within the small catchment area of the lake. The other type is characteristically rounded to subrounded, often textured with frequent silica coating and is considered to have been deposited within the lake and its catchment by aeolian processes. These aeolian grains are thought to have been transported along the main dust path that ferries aeolian dust from the Mallee region, west of the Snowy Mountains, as far as the southeastern Tasman Sea. Aeolian grains with the largest size occur over approximately the last 1.6 ka of the Holocene and this indicates an increase of climatic instability, with arid phases that commenced about 3.5 ka. At 2 ka, a wet period in southeastern Australia coincided with low aeolian input at Blue Lake. The period of consistent reduced aeolian activity spans the 7.6 to 5.5 ka interval at Blue Lake.

We present a calibrated, high-resolution O-18/O-16 and C-13/C-12 record for a well-preserved Last Interglacial Porites sp. coral (U-Th age of 127 +/- 6 ka) from the sea-level high-stand terrace of Yonaguni Island, Japan. Seasonal variations in the delta O-18 and delta C-13 values for the fossil coral are greater than those observed in modem coral records from the same reef setting and appear to be driven by the enhanced insolation seasonality in the northern hemisphere during the Last Interglacial maximum. The O-18 enrichment of 1.1 parts per thousand in the fossil coral compared to the modem analogue cannot be due entirely to a reduction in sea-surface temperature because corals in this region are already growing at their lower thermal limit. Instead, most of the O-18 enrichment must be due to a change in the delta O-18 of the surface seawater, probably in response to enhanced evaporation of the ocean or a higher volume flux of the Kuroshio Current.

The Younger Dryas chronozone, recognised in northern high-latitude areas as a cold event between 11 000 and 10 000 14C yr BP (12 900–11 600 cal. yr BP), seems to manifest itself globally in different ways. Here, we examine well-dated stratigraphic sequences together with high-resolution proxy data plots from sites across our study area, the arid–semi-arid transition zone in northern China. This climatically sensitive area of China records a cold, dry Younger Dryas climate which was punctuated by a brief period of summer monsoon precipitation. We have since found that similar climatic sequences have been reported from the Sahel and the equatorial region of Africa. Based on evidence from these sites, together with other published data, we postulate that precipitation during the Younger Dryas chronozone was indicative of a low-latitude driving force superimposed on the high-latitude cold background. This rain belt rearrangement was most probably caused by an interaction between cold air advection and summer moisture transport across the tropical Pacific Ocean. Examination of high-resolution proxies suggests short-term climate fluctuations indicative of a global teleconnection involving moist air transportation patterns from the tropics to higher latitudes, varying with ENSO and other tropical factors.

During the numerous Quaternary sea level fluctuations, the vast Gulf of Carpentaria, in northern Australia, was more often a large lacustrine basin than a shallow sea. Recovery of aeolian quartz particles in a core spanning the last 40,000 calibrated years of sedimentation identifies a ~2,600 year cyclic pattern of aridity. The most pronounced period peaks around 21,500 calibrated years BP, corresponding to the onstart of the period of lowest global sea level and glacial advance in New Zealand. The following peak of aeolian dust activity in Carpentaria just precedes the termination of the low sea level stand at 19,300 calibrated years BP. The timing of aeolian activity in northern Australia does not coincide with Heinrich events HE 1 to 3 recognised in the Atlantic Ocean, nor with the cyclicity of Chilean glacial activity, thus suggesting that separate ‘forces’ engender those different phenomena.

New sea-level information from the Bonaparte Gulf in northwestern Australia is used to constrain the magnitude and rates of change of ice volumes during the Last Glacial Maximum (LGM ). The region is tectonically stable and far from the former ice-covered regions. The glacio-hydro-isostatic adjustment of the coast is therefore relatively small, and the corrections for this eVect are not sensitive to details of the rebound model. Microfossil analysis and AMS radiocarbon dating of 11 gravity cores taken across the shelf and Bonaparte Gulf demonstrate that: (1) the LGM sea-levels were locally at ’125±4 m; (2) the LGM terminated abruptly at 19 000 cal yr BP with a rapid rise in sea-level of about 15 m over the next 500 years; and (3) the onset of the minimum sea-levels occurred before 22 000 cal yr BP. When corrected for the glacio-hydro-isostatic eVects, the increase of LGM ice volumes over the present-day ice volume is 52.5◊106 km3. The termination of the LGM is marked by a rapid ice discharge of 5.2◊106 km3. © 2001 Elsevier Science B.V. All rights reserved.

During the Last Glacial Maximum, ice sheets covered large areas in northern latitudes, and global temperatures were significantly lower than today. But few direct estimates exist of the volume of the ice sheets, or the timing and rates of change during their advance and retreat. Here we analyze four distinct sediment facies in the shallow, tectonically stable Bonaparte Gulf, Australia - each of which is characteristic of a distinct range in sea level - to estimate the maximum volume of land-based ice during the last glaciation and the timing of the initial melting phase. We use faunal assemblages and preservation status of the sediments to distinguish open marine, shallow marine, marginal marine and brackish conditions, and estimate the timing and the mass of the ice sheets using radiocarbon dating and glacio-hydroisostatic modelling. Our results indicate that from at least 22,000 to 19,000 (calendar) years before present, land-based ice volume was at its maximum, exceeding today's grounded ice sheets by 52.5 x 10 exp 6 cu km. A rapid decrease in ice volume by about 10 percent within a few hundred years terminated the Last Glacial Maximum at 19,000 +/- 250 years.

The last two glacial/interglacial cycles represented in core MD88-779 in the southeastern Indian Ocean over the South Tasman Rise (47°50.69′S, 146°32.75′E; 2260 m water depth) have been analysed. An oceanographic reconstruction for this region is presented, based principally on the recovery of benthic foraminiferal and diatom assemblages. The most striking feature of the microfossil record from core MD88-779 is the `lack' of diatoms during glacials, despite evidence of high oceanic productivity. Benthic foraminiferal data suggest significant increases in ocean surface productivity during glacial periods and, in particular, during isotopic stages 2, late 3 and 6. For these periods of elevated surface productivity, substantial, and at times total, dissolution of diatom frustules occurred. We propose that increased influx of aeolian dust and especially associated iron during glacial periods may have reduced the intake of silica in diatoms, thus resulting in less silicified diatoms. Additionally, winnowing is suggested to have removed remaining frustules from the sedimentary record. Increased productivity at the sea-surface is indicative that both the Subtropical Front and the Subantarctic Front may have shifted northward during glacial periods and that the Subantarctic Front was near the coring site on the South Tasman Rise for these periods. We also postulate, based on diatom floral evidence, that southward-moving eddies generated by the subtropical East Australian Current may have intermittently reached the coring site even during glacial periods.

This paper describes a series of in vitro experiments during which juveniles of the euryhaline ostracod Cyprideis australiensis were grown to adulthood in waters of ranging salinities (from 10‐70‰.) and Mg=Ca and Sr=Ca ratios, and under two different constant temperature regimes, 20o and 25oC. Results indicate the following thermodependence for Mg in the calcitic valves of adult Cyprideis australiensis: T.Mg/D 2:69C 5230 [Mg=Ca]ostracod=[Mg=Ca]water .A minor thermodependence was also found for this ostracod species with respect to the uptake of Sr. There is a very strong relationship between the Mg=Ca of the ostracods and the Mg=Ca of the waters in which they moulted. The same can be said between the Sr=Ca of the ostracods and the waters’ Sr=Ca. There is no direct relationship between water salinity and either the Mg=Ca ratio nor the Sr=Ca ratio of the ostracod valves. The 20o and 25oC experiments established the following partition coefficients which we believe can be applied to any Cyprideis taxa grown in waters within the 5 to 20 Mg=Ca range: KD[Mg]D 0:000514C 0:00019 Temperature oC , and KD[Sr]D 0:223C 0:0086 Temperature oC . This relationship for Sr, which has been mentioned for the first time for Cyprideis is tentative. The Mg=Ca of ostracods is strongly dependant on temperature, but this effect can easily be masked by variations in the Mg=Ca of the host water commonly found in natural lakes. Ostracod physiology is adapted to constructing valves from low-Mg calcite, so when growing in waters with high (>30), or very low (

Palaeoceanographic conditions in the eastern Indian Ocean for the last30 kyr are documented by means of planktonic foraminiferal analyses of 10 gravity cores. Quantitative foraminiferal analysis (%), Q-mode factor analysis, the modern analog technique (MAT) and oxygen-isotope analyses are used. A conspicuous increase during the last glacial maximum (LGM) of foraminiferal fragmentation resulting from a more productive Java upwelling system and=or a more corrosive Antarctic Intermediate Water (AAIW) was found at intermediate water depths (1000 m). Contrasting Q-mode factors based on foraminifera between today and the LGM suggest changes in the thermocline depth, sea-surface temperature (SST), upwelling, and the strength of both the Australasian Mediterranean Water (AAMW) and the Indian Central Water (ICW). The decrease in the percentage abundance of shallow-dwelling and symbiont-bearing planktonic foraminifera, the increase in percentage of the upwelling-related species Globorotalia cultrata and Neogloboquadrina dutertrei , and factor 3 (dominated by Globorotalia tumida and Globigerinella siphonifera) suggest a stronger Java upwelling system during the LGM. A steeper, steric latitudinal gradient (in the presence of a weak Leeuwin Current), and a geostrophic flow similar to today’s is postulated for the LGM, and this must have prevented upwelling offshore Western Australia. Today’s AAMW‐ICW sharp front was weaker during the LGM when the AAMW was saltier, cooler, and nutrient richer and more similar to the ICW. During the LGM, a more gentle SST latitudinal gradient over the16 to23oS region contrasts with today’s steeper conditions at the AAMW‐ICW Front. Also, for the LGM, a nutrient-rich ICW may explain previously documented increases in mass accumulation rates of CaCO3, organic carbon and benthonic foraminifera in a region where the nutricline was deep and within the lower euphotic zone. © 1999 Elsevier Science B.V. All rights reserved.

Faunal assemblages, principal component (PCA), canonical correspondence (CCA), and factor analysis are applied to planktonic foraminifera from 57 core-top samples from the eastern Indian Ocean. The foraminiferal lysocline occurs at ∼2400 m north of 15°S where carbonate dissolution is induced by the Java upwelling system, and occurs deeper south of 15°S where carbonate dissolution is characteristic of the oligotrophic regions in the Indian Ocean. Dissolution effects, the February standing stock at the time of collection of the plankton-tow material, and different production rates explain the different foraminiferal assemblages found between plankton-tow and core-top samples. Core-top samples are differentiated by PCA into four groups — Upwelling, Western Pacific Warm Pool (WPWP), Transitional, and Southern — that are related to environmental variables (temperature, salinity and nutrients); all environmental variables follow a strong latitudinal component as indicated by the CCA analysis. Similarly, three assemblages are recognized by factor analysis: Factor 1 (dominated by Globigerinoides sacculifer , G. ruber , Globigerinita glutinata and Globorotalia cultrata ), factor 2 (dominated by Globigerina bulloides and Globorotalia inflata ) and factor 3 (dominated by Neogloboquadrina dutertrei ) explain more than 92% of the variance, and are related to sea-surface temperature, thermocline depth and nutrient levels. The seasonal influence of the Java upwelling system supplies nutrients, phyto- and zooplankton to the oligotrophic eastern Indian Ocean (factor 1). South of ∼24°S, a deep chlorophyll maximum, a deep euphotic zone, a deep thermocline, SSTs below ∼22°C, and brief upwelling pulses seem to explain factors 2 and 3. The ratio of G. sacculifer and N. dutertrei , two mutually excluding species, appears to indicate the southern boundary of the WPWP. This ratio is applied to core Fr10/95-11 to demonstrate past shifts of the southern boundary of the WPWP.

Living and sub-recent ostracods were collected from four lakes and foul springs, located in Belgium, France and Spain, characterized by low water Mg/Ca ratios (from 0.08 to 0.65). Valves of ostracods belonging to Cyprideis torosa, Candona neglecta, C. marchica and C. candida have been extensively analysed for their magnesium and strontium contents with respect to calcium. Comparisons of these results are made using the same elements from the waters in which the ostracod valves calcified. Our results offer new and somewhat different interpretations with respect to the uptake of Mg and Sr in the calcitic ostracod valves. These findings include the following. (1) The partition coefficient L)(Sr for ostracods belonging to the same genus (Candona) is not a constant. The observed variability in D(Sr) values could be due to the rare of biological calcification, although more investigations are necessary to assess the influence of this factor; it is possible that some taxa grouped under the genus Candona belong to a different genus. (2) Even at the species level (Cyprideis torosa), the ostracod D(Sr) cannot be considered to be constant. At low water Mg/Ca ratio (0.65), our D(Sr) value for C. torosa is higher than those determined by others for C. torosa calcified in evolved marine water. (3) The Mg/Ca ratio of the water appears as a major factor influencing D(Mg) for ostracods. For low water Mg/Ca values (< similar to 2), D(Mg) drastically increases. This phenomenon is also effective for inorganic calcite; implying a non-biologic effect that could be linked to Mg2+ adsorption. Consequently, large variations in ME content of fossil ostracod valves from selected lacustrine sequences, with expected low water Mg/Ca(< similar to 2), can be due to small variations in water Mg/Ca. (C) 1998 Elsevier Science B.V. All rights reserved.

The terrigenous fraction of sediments from a deep-sea sediment core recovered from the northwestern Western Australian continental slope offshore North West Cape, SE Indian Ocean, reveals a history of Western Australian climate throughout the last 550 ka. End-member modelling of a data set of grain-size distributions (n = 438) of the terrigenous sediment fraction allows to interpret the record in terms of aeolian and fluvial sediment deposition, both related to palaeo-environmental conditions in the North West Cape area. The data set can be best described by two aeolian end members and one fluvial one. Changes in the ratio of the two aeolian end members over the fluvial one are interpreted as aridity variations in northwestern Western Australia. These grain-size data are compared with bulk geochemical data obtained by XRF scans of the core. Log-ratios of the elements Zr/Fe and Ti/Ca, which indicate a terrigenous origin, corroborate the grain-size data. We postulate that the mid- to late Quaternary near North West Cape climate was relatively arid during the glacial and relatively humid during the interglacial stages, owing to meridional shifts in the atmospheric circulation system. Opposite to published palaeo-environmental records from the same latitude (20°S) offshore Chile and offshore Namibia, the Australian aridity record does not show the typical southern hemisphere climate variability of humid glacials and dry interglacials, which we interpret to be the result of the relatively large land mass of the Australian continent, which emphasises a strong monsoonal climatic system.

Analyses of the Mg/Ca and Sr/Ca ratios of the modern benthic foraminifera, Cibicides wuellerstorfi (epifaunal) and Uvigerina species (infaunal) from the Coral Sea, and Cibicides refulgens (epifaunal) and Trifarina angulosa (infaunal) from Prydz Bay, Antarctica revealed relationships with temperature that have possible applications for reconstructions of bottom-water paleotemperatures. A positive relationship exists between the Mg/Ca and Sr/Ca ratios of Cibicides wuellerstorfi and Cibicides refulgens and ambient temperatures, at least within the range of -2 and 6°C. For the correlation between Mg/Ca compositions and temperature the r2 values range from 0.78 (C. wuellerstorfi alone) to 0.88 (C. wuellerstorfi and C. refulgens together). At present, the Mg/Ca-temperature relationship must be regarded as tentative because of significant overlap of standard error values. The relationship between the Sr/Ca compositions of C. wuellerstorfi and bottom-water temperature yields an r2 value of 0.95. These results indicate that Sr/Ca and possibly Mg/Ca ratios of Cibicides wuellerstorfi may provide useful information for the assessment of paleotemperature. Single-species data are presently insufficient to assess the influence of ambient temperature on trace-element compositions of Uvigerina species. Trifarina angulosa may have Mg/Ca compositions which are positively related to temperature, but Sr/Ca values seem unaffected by temperature. This may be due to pore-water influences on infaunal tests or to vital effects. Although more modern data are needed, our present results suggest that Sr/Ca ratios and possibly Mg/Ca ratios of some benthic foraminifera have the potential to be useful paleothermometers, at least within a temperature range of −2 to 6°C.

The composition of the late Quaternary calcareous nannoplankton in three deep-sea cores RC12-113, Z-2108 and GC-3, located along a N-S transect at three different latitudes (25°, 33°, 44°S) in the Tasman Sea, has been investigated. The shift in floral dominance from small Gephyrocapsa to small placoliths (labelled here “Small Placolith”), and then to Emiliania huxleyi is recognized at stage 5 and stage 4, respectively, in cores RC12-113 and Z-2108. However, the occurrence of small Gephyrocapsa and Small Placolith displays a seesaw relationship in core GC-3 which is located today just north of the Subtropical Convergence, east of Tasmania. Gephyrocapsa muellerae and Coccolithus pelagicus increase their abundance geographically southwards and stratigraphically during glacial periods, whereas the percentage abundances of Florisphaera profunda and Umbilicosphaera sibogae demonstrate reverse patterns. The relationships between the percentage abundance of each nannoplankton species and the δ 18 O record for three cores are discussed in detail. A transfer function for estimating past sea-surface temperatures (= TN) is attempted here; it is based on core-top data from the Tasman Sea and provides a good relationship between some calcareous nannoplankton assemblages and modern mean summer sea-surface temperatures. The TN value shows a good correspondence with the δ 18 O record in all three cores. Core GC-3 is much affected by CaCO 3 dissolution in comparison with cores RC12-113 and Z-2108. The calcareous nannoplankton dissolution patterns recognized in the three cores do not show a systematic correspondence with the δ 18 O record. Of interest, however, is the good preservation peaks that are recognized in all three cores at the transitions from glacial to interglacial events.

Over 180 surface sediment samples from the Southwest Pacific Ocean were investigated for their planktonic foraminiferal (> 149 μm), opaline and terrigenous sediment content, with the aim to determine the oceanic conditions at the sea surface above the sampling sites. High concentrations of biogenic opal are related to high productivity levels recognised in tropical surface waters. The abundance of this biogenic opal found within the sediments on the ocean floor shows a slight decrease as one approaches the Australian landmass, and also poleward from the equatorial belt. The distribution of major species of planktonic formainifers reflects different surface water masses. Q-mode factor analysis of planktonic foraminiferal percentage data from 63 core tops permits identification of several characteristic formainiferal assemblages for the Southwest Pacific Ocean. Four factors explain up to 95.5% of the total variance. Factor 1 (66%) is dominated by the tropical-subtropical species Globigerinoides sacculifer and Globigerinoides ruber. The transitional to subpolar species Globorotalia inflata is important in factor 2 (12%). The temperate-cool factor 3 (13%) is characterised by Turborotalia quinqueloba and Globigerinita glutinata. Factor 4, which explains 3% of the total variance and which is represented by several species, is assigned to the high productive equatorial and coastal waters off the Australian continental margin. Palaeoecological equations permitting an estimate of sea-surface temperatures and salinities are presented. The correlation coefficients between modern data adapted from literature and estimated by transfer function FP 4 (transfer function for planktonic formainifers) are 0.95 (for temperature) and 0.77 (for salinity).

Ostracod assemblages and geochemical analyses of valves of specific ostracod taxa are used to reconstruct, both qualitatively and quantitatively, bottom-water temperatures (BWT) for the last 1000,000 years in the western Coral Sea. The investigated core (51GC21) is situated in the lower reaches of the Antarctic Intermediate Water, at 1630 m water depth. First, we ran a Principal Coordinate Analysis (PCoA) of 42 surfaces samples from the Coral Sea, and then compared fossil assemblages with results of the PCoA. In addition, we selected well preserved specimens of the two genera #Krithe$ and #Bythocypris$ for Mg/Ca analyses. The Mg/Ca is used to infer past changes in BWT for intermediate waters of the western Coral Sea ; results indicate large temperature fluctuations over the last 100,000 years. Of interest is the documentation that the BWT was similar to the present-day temperature during part of Isotope Stage 3. Comparison between our temperature record and the benthic foraminifer delta 18O record of core 51GC21, and with the delta 18O variations in seawater, as reconstructed by Labeyrie et al. (1987), allowed assesment of past changes in BWT salinity and density. Thus, we identify for the western Coral Sea three distinct periods on the basis of water mass density changes (i.e. for Isotope Stage 1, Stages 2, 3 and 4, and Stage 5). Our temperature record also indicates a good correlation with the 60°S summer insolation calculations for the period between 25,000 yr B.P. and 75,000 yr B.P. Comparison of our results from this study with other records from the western Pacific (the Ontong Java Plateau in particular) reveal the role of New Guinea as an oceanographic barrier. A wet phase recorded on continental Australia coincides with our high bottom-water temperature record for isotopic Stage 3. (Résumé d'auteur)

Several proxies have been developed to reconstruct past sea surface temperature (SST), but different proxies may reflect temperatures of different seasons and each proxy is characterized by certain uncertainties. Therefore, a multiproxy approach is preferred to precisely reconstruct SST. Here, we reconstruct SST of the ocean offshore southeastern Australia (Murray Canyons area) for the last ~135?ka using three independent organic proxies (TEXH86 based on glycerol dialkyl glycerol tetraethers (GDGTs), UK'37 based on alkenones, and LDI based on long-chain diols) in addition to foraminiferal faunal assemblages. The organic proxy records show similar trends, with the highest temperature (21°C for UK'37 and TEXH86, and 25°C for LDI) during the last interglacial and lowest temperature (8°C for TEXH86, 10°C for UK'37, and 12°C for LDI) during the Last Glacial Maximum. However, the differences in absolute SST estimates obtained by the organic proxies varied over time with differences of up to 9°C between LDI and TEXH86. The seasonal SST reconstructions based on the modern analogue of foraminiferal assemblages also show similar trends as the organic proxies with highest temperatures during the last interglacial (23°C for the warmest month SST, 20°C for mean annual, and 18°C for the coolest month) and lowest temperature during the Last Glacial Maximum (14°C for the warmest month, 11°C for mean annual, and 9°C for the coolest month). Down core comparison between the reconstructed SSTs of the organic and inorganic proxies shows that LDI-inferred temperatures compare well with the temperature of the warmest month, TEXH86 with the temperature of the coolest month, and UK'37 with mean annual temperature. An increase in TEXH86 SST estimates relative to those of other proxies during deglaciations and interglacials suggests that either winter temperatures rapidly warmed, possibly due to an invigoration of the Leeuwin Current over the core site, or there was a change in the growth season of the Thaumarchaeota, the source organism of GDGTs. Our study shows the benefits of a multiproxy approach in the interpretation of SST proxies, leading to a more robust knowledge of past ocean temperature changes.

The evolution of the Australian monsoon in relation to high-latitude temperature fluctuations over the last termination remains highly enigmatic. Here we integrate high-resolution riverine runoff and dust proxy data from X-ray fluorescence scanner measurements in four well-dated sediment cores, forming a NE-SW transect across the Timor Sea. Our records reveal that the development of the Australian monsoon closely followed the deglacial warming history of Antarctica. A minimum in riverine runoff documents dry conditions throughout the region during the Antarctic Cold Reversal (15-12.9 ka). Massive intensification of the monsoon coincided with Southern Hemisphere warming and intensified greenhouse forcing over Australia during the atmospheric CO2 rise at 12.9-10 ka. We relate the earlier onset of the monsoon in the Timor Strait (13.4 ka) to regional changes in landmass exposure during deglacial sea-level rise. A return to dryer conditions occurred between 8.1 and 7.3 ka following the early Holocene runoff maximum.

Ostracods belonging to the genus Bennelongia differ much in valve morphology between adults and juveniles. Adult valves are asymmetrical, characterised by a beak-like feature in the antero-ventral region of the left valve, and, with some notable exceptions, mostly have smooth or weakly-ornamented valves. Juvenile specimens, on the other hand, have valves that are almost symmetrical, with no beak-like feature and are often heavily ornamented. We have examined the last 3 - 4 juvenile stages of 6 Bennelongia species from 5 different lineages, in order to decipher the types of external valve ornamentation and their recurrences during ontogeny and across lineages. It is clear that ornamentation is more prevalent at the early instar stages compared to the last 2 pre-adult stages, and especially when compared to the adult stage itself. We also examined the surprising presence of a calcified inner lamella with a prominent inner list in the pre-adult stages of Bennelongia species, that is usually absent in juveniles of other ostracods, thus questioning if heterochronic processes have provided an intermediate valve morphology between the simple (normal) cypridinid juvenile state and the heavily derived and modified state of adult Bennelongia. We discuss the possible (speculative) functionality of the ornamentation in juveniles.