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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2008.10.003 Byline: Ronald E. Thresher (a), Colin M. MacRae (b), Nick C. Wilson (b), Stewart Fallon (c) Keywords: Calcium; Environmental effects; Gorgonian; Growth rate; Isidella; Lepidisis; Keratoisis; Magnesium; Phosphorous; Radiocarbon; Strontium; Sulphur Abstract: We test two hypotheses, that annual environmental cycles produce periodic variability in the skeletal composition of deep-water gorgonians, and that these cycles can be counted to determine the coral's age. Annual periodicity of deposition was tested by comparing the internode composition of bamboo corals live-collected 10 years apart in the Southern Ocean. The validity of the comparison was substantiated by growth rates for the 10-year interval (77-121[mu]m/yr) that were confirmed by radiocarbon analysis. Variability in Mg/Ca and possibly S/Ca, but not Sr/Ca or P/Ca, was consistent with annual cycles of deposition. However, spectral analysis of Mg/Ca data for a larger coral showed little or no spectral peak associated with an annual cycle of deposition (though there were peaks at periods of 4-5 and 11-15 years). The absence of an annual peak is likely to reflect growth rates that vary over time, coral cross-sections that change shape over time, and interannual differences in the seasonal range of environmental variability. The resulting subjectivity in what defines an annulus, along with evidence that the nature and extent of annual periodicity differs among sites, means that the technique is likely to be inherently imprecise and to require independent validation for each site and taxon before it can be applied. Author Affiliation: (a) CSIRO Marine and Atmospheric Research and Wealth from Oceans Flagship, GPO Box 1538, Hobart, Tasmania, Australia (b) CSIRO Minerals, Clayton, Victoria, Australia (c) Research School of Earth Sciences, Australian National University, Canberra, Australia Article History: Received 28 March 2008; Revised 12 October 2008; Accepted 21 October 2008

Investigations of flow-stimulated bioluminescence have been recorded throughout the world's ocean for centuries. The use of naturally occurring bioluminescence is explored, within a laboratory context, as a strategy towards visualizing oceanic flow fields.

Highlights • XRD, SEM and C isotope data were used to investigate carbonate mineral and hydrotalcite formation within mine tailings. • CO 2 availability controls carbonate with depth in the tailings at Woodsreef. • Pyroaurite and coalingite are sequestering atmospheric CO 2 at the Woodsreef chrysotile mine. • Isotope fractionation in hydrotalcites depends on carbon availability. • Detailed carbon accounting requires quantitative XRD and elemental C analysis. Abstract Carbon mineralisation of ultramafic mine tailings can reduce net emissions of anthropogenic carbon dioxide by reacting Mg-silicate and hydroxide minerals with atmospheric CO 2 to produce carbonate minerals. We investigate the controls on carbonate mineral formation at the derelict Woodsreef chrysotile mine (New South Wales, Australia). Quantitative XRD was used to understand how mineralogy changes with depth into the tailings pile, and shows that hydromagnesite [Mg 5 (CO 3) 4 (OH) 2 ·4H 2 O], is present in shallow tailings material (<40 cm), while coalingite [Mg 10 Fe3+ 2 (CO 3)(OH) 24 ·2H 2 O] and pyroaurite [Mg 6 Fe3+ 2 (CO 3)(OH) 16 ·4H 2 O] are forming deeper in the tailings material. This indicates that there may be two geochemical environments within the upper ∼1 m of the tailings, with hydromagnesite forming within the shallow tailings via carbonation of brucite in CO 2 -rich conditions, and pyroaurite and coalingite forming under more carbon limited conditions at depth. Radiogenic isotope results indicate hydromagnesite and pyroaurite have a modern (F14C > 0.8) atmospheric CO 2 source. Laboratory-based anion exchange experiments, conducted to explore stable C isotope fractionation in pyroaurite, shows that pyroaurite δ13C values change with carbon availability, and 13C-depleted signatures are typical of hydrotalcites in C-limited environments, such as the deep tailings at Woodsreef. Quantitative XRD and elemental C data estimates that Woodsreef absorbs between of 229.0–405.1 g CO 2 m−2 y−1. [ABSTRACT FROM AUTHOR]

We test for trace element proxies in the high-magnesium calcite fraction of bamboo coral internodes by comparing environmental conditions and growth rates to the specimen-mean compositions of 73 corals that were live-caught at depths ranging from 3 to 3950 m and collected from habitats ranging from tropical coral reefs to the Antarctic slope. Comparisons were done at a large geographic scale (LGS) and for a well sampled area south of Australia, across depths at a single site, in order to help separate the effects of environmental variables that co-vary at one spatial scale, but not the other. Thirty-seven trace elements were measured using solution-based Sector Field ICP-MS, of which seventeen were significantly detected in more than a third of the specimens. Only eight element/calcium ratios correlated significantly with any environmental variable at the large geographic scale, and only four did so at the local level. At the LGS, the highest correlation was between ambient temperature and Mg/Ca, which accounted for 89% of the variance across specimens, spanned all four Isidid sub-families and was independently significant in the two best sampled sub-families. The predictive (geometric mean) relationship is T ( ° C ) = - 23.9 ( ± 2.46 ) + 0.34 ( ± 0.25 ) Mg / Ca ( mmol / mol ) spanning a temperature range of −1.9 to 26.8 °C, Mg/Ca ratios from 58.6 to 155.1 mmol/mol, and an uncertainty (RMS) of 2.78 °C. The numbers in parentheses are 95% CIs. The slope of the regression does not differ significantly from that of abiotic high-Mg calcites, which suggests that the temperature-dependent incorporation of Mg into the carbonate results from kinetic reactions at the crystal surface. Analysis at the SH scale for the sub-set of specimens for which we had data suggests is also affected by growth rates. There were no obvious trace element correlates at either spatial scale of salinity or oxygen levels that could not be accounted for by covariance between these environmental parameters and, in most cases, temperature. Single and multiple correlation analyses also confirm previous suggestions that Ba/Ca in bamboo coral calcite is a proxy for seawater barium and hence refractory nutrients, suggest that Sr/Ca is influenced by specimen-mean Mg/Ca ratios and water temperature as well as possibly seawater Sr/Ca, and falsify for bamboo corals P/Ca (as well as P/Cd and Cd/Ca) as a proxy for seawater phosphate levels. The predictive relationship between Isidid skeletal-mean Ba/Ca and seawater silicate concentrations appears to be linear, and is given by silicate ( μ mol kg - 1 ) = - 56.7 ( ± 20.8 ) + 9217 ( ± 1632 ) Ba / Ca ( mmol / mol ) spanning a silicate range of 0.5 to 120 μmol kg −1 , a Ba/Ca range of 0.0042 to 0.0195 mmol/mol, and with an uncertainty (RMS) of 33.1 μmol kg −1 . Mn/Ca differences among specimens and sites are highly significant and appear to reflect seawater Mn, suggesting a proxy for this micronutrient. The compilation of growth rate data across 34 specimens indicates a wide range of growth rates even among con-familial specimens from within a single habitat, and suggests both ambient temperature and food availability underlie at least part of this variability. [ABSTRACT FROM AUTHOR]

Highlights: [•] Passive uptake of atmospheric CO2 offsets 11% of annual emissions at Mount Keith. [•] Carbon mineralization in mine tailings is limited by CO2 supply. [•] The rate of brucite carbonation is a major control on carbon mineralization. [•] Recommendations are made for tailings management practices that enhance carbonation. [Copyright &y& Elsevier]

Marine reservoir ages are a key element in calculating and constraining uncertainty in radiocarbon age estimates and are also essential to better understand regional ocean circulation. In this study, we present a new method to reconstruct long-term, high-resolution sea surface reservoir ages based on analysis of the organic skeleton of deep-sea (560 m) black coral (Anthozoa, Antipatharia). Our results confirm that antipatharians are extremely slow growing (typical radial growth rate for a South Pacific specimen around 0.03 mm/yr). Coupled uranium series and radiocarbon measurements were made on black coral collected live from the Norfolk Ridge (north Tasman Sea) to provide the first modern reservoir ages for this region. At the Norfolk Ridge, the average reservoir age between 1790 AD and 1900 AD was ∼330 years. This was followed by a steep decrease over time of about 70 years to 1950 AD (our most modern value). This indicates an increase in surface ocean ventilation of water masses in this region. These results are consistent with observational studies for the early twentieth century, which suggest significant changes in regional circulation of the southwest pacific. [ABSTRACT FROM AUTHOR]

The study of the paleoenvironment depends upon proxies of palaeovegetation associated with chronological records. Carbon stable isotopes in soil samples provide information on the past vegetation type due to differences in mass fractionation during photosynthesis. Radiocarbon measurements on soil organic matter may also have different behaviors, given the complexity of soils as mixtures of multiple sources. With the aim of investigating how different soils, under different vegetation coverages, may affect paleoenvironmental reconstructions, we have analyzed four soil profiles collected at the Itatiaia National Park, between Rio de Janeiro and Minas Gerais states in Brazil, in the context of the Atlantic Forest biome, at altitudes between 1898m and 2457m. Different chemical fractions of the bulk soil were separately 14C dated for each sample depth. For the total soil and the non-hydrolyzable carbon, discrepancies in pMC values were mostly within 5% from the humin fraction values. Two Histosol profiles collected under forest vegetation on a hillside presented very different morphologies and chronologies, possibly related to colluvium effect, indicated by the deposition of originally older material. The results for a Histosol profile under grassland indicates that C3 plants were the dominant vegetation over most of the last 8000 years at the most distant location while a Cambisol profile under transitional vegetation shows variations, with C3 plants at ca. 2 kyr BP, switching to C4 before ca. 700 yr BP, suggesting anthropic influence. [ABSTRACT FROM AUTHOR]

Radiocarbon measurements reveal that soil carbon is often hundreds to thousands of years old; significantly older than the annual flux of carbon through the soil would suggest. Models deal with this discrepancy by conceptualizing soil carbon as having fast and slow cycling pools. The Rothamsted Soil Carbon Model contains an inert pool for this reason. Here we use a unique record of time-series radiocarbon measurements from long-term trials to demonstrate that the inert pool is hardly inert, and that its mean age varies from 2000 to as little as 90 years depending on carbon flow through the soil. This finding suggests that the concept of truly inert organic matter requires redefinition to account for the enhanced probability that microorganisms will overcome barriers to previously inaccessible organic matter as their activity increases. [ABSTRACT FROM AUTHOR]

In this study we have used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to produce a high resolution coral record of rare earth elements (REE), Mn and Ba from coastal Porites corals from the Great Barrier Reef of Australia. Validation of the LA-ICP-MS technique indicated that the method provides accurate and reproducible (RSD = 13–18%) analysis of low concentration REE in corals (∼1 to 100 ppb). The REE composition in coral samples was found to closely reflect that of the surrounding seawater and distribution coefficients of ∼1–2 indicated minimal fractionation of the series during incorporation into coral carbonate. To explore the idea that coral records of REE can be used to investigate dissolved seawater composition, we analyzed two coastal corals representing a total of ∼30 yr of growth, including a 10-yr overlapping period. Comparable results were obtained from the two samples, particularly in terms of elemental ratios (Nd/Yb) and the Ce anomaly. Based on this evidence and results from the determination of distribution coefficients, we suggest that useful records of seawater REE composition can be obtained from coral carbonates. When compared to the REE composition of a mid shelf coral, coastal corals showed a significant terrestrial influence, characterized by higher REE concentrations (greater than 10 times) and light REE enrichment. The REE composition of coastal seawater inferred from the coral record was dependent on seasonal factors and the influence of flood waters. REE fractionation displayed a strong seasonal cycle that correlated closely with Mn concentration. We suggest that higher Nd/Yb ratios and higher Mn concentrations in summer result from scavenging of heavy REE by particulate organic ligands and Mn reductive dissolution respectively, both processes displaying higher rates during periods of high primary productivity. The Ce anomaly also displayed a strong seasonal cycle showing an enhanced anomaly during summer and during flood events. This is consistent with the Ce anomaly being primarily controlled by the abundance of Ce oxidizing bacteria. Based on these arguments, we suggest that the coral record of dissolved REE and Mn may be regarded as a useful proxy for biological activity in coastal seawater. [Copyright &y& Elsevier]

Massive corals in the Great Barrier Reef, analyzed at high-resolution for Sr/Ca (thermal ionization mass spectrometry) and trace elements such as Ba and Mn (laser ablation inductively coupled plasma mass spectrometry), can provide continuous proxy records of dissolved seawater concentrations, as well as sea surface temperature (SST). A 10-yr record (1989 to 1998) from Pandora Reef, an inshore reef regularly impacted by the freshwater plumes of the Burdekin River, is compared with an overlapping record from a midshelf reef, away from runoff influences. Surface seawater samples, taken away from river plumes, show little variability for Sr/Ca (8484 ± 10 μmol/mol) and Ba (33.7 ± 0.7 nmol/kg). Discrete Ba/Ca peaks in the inshore coral coincide with flood events. The magnitude of this Ba/Ca enrichment is most likely controlled by the amount of suspended sediments delivered to the estuary, which remains difficult to monitor. The maximum flow rate at peak river discharge is used here as a proxy for the sediment load and is shown to be strongly correlated with coral Ba/Ca (r = 0.97). After the wet summer of 1991, the coral Ba/Ca flood peak is followed by a plateau that lingers for several months after dissipation of plume waters, signifying an additional flux of Ba that may originate from submarine groundwater seeps and/or mangrove reservoirs. Both Mn and Y are enriched by a factor of ∼5 in inshore relative to midshelf corals. Mn/Ca ratios show a seasonal cycle that follows SST (r = 0.7), not river discharge, with an additional high variability in summer suggesting a link with biological activity. P and Cd show no significant seasonal variation and are at a low level at both inshore and midreef locations. However, leaching experiments suggest that part of the coral P is not lattice bound. [Copyright &y& Elsevier]

Several scientific expeditions surveyed the ocean during the 19th century, gathering a wealth of interdisciplinary data as well as samples of different kinds. The latter are currently held by museums worldwide, and are the subject of study in different sciences, offering a unique opportunity to access information which is not readily available elsewhere. This is the case for research involving the offset in 14C (or radiocarbon) activity between the ocean and the atmosphere, termed the Marine Reservoir Effect (MRE), which is responsible for apparent 14C ages in marine material. The quantification of this discrepancy is crucial for the 14C dating tool since corrections must be applied for the accurate calibration of marine 14C ages. Nevertheless, the difficulty of finding suitable material for assessing the MRE contributes to the current scenario of scarce and patchy data. Here we propose the use of samples collected during well-documented 19th-century scientific expeditions in order to overcome the lack of information that prevents the use of many museum specimens in MRE studies. Approximately 60 mollusk shells and a sea urchin, collected from the coast of Brazil, were analysed for their radiocarbon age, δ 13C and δ 18O. The MRE is variable, with considerably high values occurring at specific spots along the shoreline. The data indicate a rather large area of upwelling influence on the southeastern coast of Brazil and possible dissolution of 14C-free limestone in the northeast. The results shed light on processes affecting the 14C concentration of Brazilian coastal waters, bearing implications for palaeoenvironmental and archaeological studies performed in the region. Moreover, the data generated in this study will be useful for the validation of 14C simulations in numerical models. Finally, this paper offers a discussion of the importance of natural history collections which looks beyond the preservation of our biodiversity. [ABSTRACT FROM AUTHOR]

Deep-sea corals are an important component of benthic ecosystems, but are potentially very vulnerable to ecological disturbance due to their extreme longevity and slow growth rates. Among the slowest growing genera are the 'Black Corals' (Family Antipatharia), which can have lifespans of millennia. The waters around New Zealand contain a variety of black corals, including species that grow at shallow depths in the southern Fjords. However, while growth rates in black corals have been reported for many other parts of the world, New Zealand's black corals have received little attention. Here we present a series of high-resolution radiocarbon dates for coral colonies of the genera Antipathella , Leiopathes and Antipathes. Our results illustrate some corals have lifespans of up to 3000 years and slow but highly variable growth (averaging 10–100 μm/yr) for genera Leiopathes and Antipathes and fast growth (averaging 2–3 cm/yr) for genera Antipathella , with no obvious regional variability in growth rates over time. Our results are broadly consistent with other black coral growth rate studies, and reinforce that New Zealand's black corals likely have low resilience to any disturbance. • Deep-sea black corals show extreme longevity on the order of several millennia. • Slow growth suggests black corals are highly susceptible to any disturbances. • Growth rates do not exhibit regional patterns based on food availability. • Growth rate is intrinsic to species. [ABSTRACT FROM AUTHOR]

Over the last decade, two major calving events of the Petermann Ice Tongue in Northwest Greenland have led to speculation on its future stability and contribution to further Greenland Ice Sheet mass loss. However, it has been unclear if these events are anomalous or typical within the context of limited historical observations. We extend the historical record of the floating ice tongue using the stratigraphy of Petermann Fjord sediments to provide a longer-term perspective. Computed tomography (CT) scans, X-Ray Fluorescence (XRF) scans, Ice-Rafted Debris (IRD) counts, and the magnetic properties of specific particle size fractions constrain changes in depositional processes and sediment sources at our core sites, allowing for reconstructions of past behavior of the Petermann Ice Tongue. Radiocarbon dating of foraminifera, 210Pb, and paleomagnetic secular variation (PSV) provide age control and help to address uncertainties in radiocarbon reservoir ages. A floating ice tongue in Petermann Fjord formed in late glacial time as Petermann Glacier retreated from an advanced grounded position. This paleo-ice tongue broke-up during the early Holocene when high northern latitude summer insolation was higher than present. After gradual regrowth of the ice tongue associated with regional cooling, the ice tongue reached its historical extent only within the last millennium. Little or no ice tongue was present for nearly 5000 years during the middle Holocene, when decadal mean regional temperatures are estimated to be 0.8–2.9 °C higher than preindustrial (1750 CE) and seasonal sea-ice in the Lincoln Sea was reduced. This pre-historical behavior shows that recent anthropogenic warming may already be in the range of ice tongue instability and future projected warming increases the risk of ice tongue break-up by the mid-21st Century. • A transect of sediment cores constrain past retreat and advance of Petermann Glacier's floating ice tongue. • Particle-size specific properties disentangle sedimentary source and transport signals. • Multi-proxy age-depth modeling constrains the timing of glacial changes. • Petermann Ice Tongue broke-up during early Holocene warming and was absent for nearly five of the last seven thousand years. • Historically observed ice tongue extents of Petermann Glacier are only characteristic of the latest Holocene. [ABSTRACT FROM AUTHOR]

The Holocene epoch offers a potential analogue for understanding future sea-level variability as both SST's and Global Mean Sea Levels (GMSL) were at times higher than observed today. However, GMSL can differ significantly from Relative Sea Level (RSL), even at far-field sites remote from margins of former ice sheets. Much of this spatial variability has been shown to be consistent with the predictions of glacial isostatic adjustment (GIA) models. Whilst it is generally accepted that RSL at far-field sites reached its maximum during the mid-Holocene, there have been many interpretations of sea level fall following the highstand from ∼6 ka. Here, we present a RSL history from several tectonically stable, far-field sites in eastern Brazil, derived from 17 microatoll and 45 fossil reef flat ages. Our results show evidence for two periods of RSL instability during the Holocene which differ from GIA predictions, including a hiatus in reef growth ∼3.7–2.5 ka. These results are broadly synchronous with several other locations in the Southern Hemisphere suggesting global rather than regional climatic forcing mechanisms are responsible. Variations in SST and southern hemisphere ice sheet dynamics are proposed as possible controlling mechanisms for the observed RSL oscillations beginning at ∼3.7 ka and 2 ka respectively. We suggest that these global processes combined with increased precipitation (and higher sediment flux) from several regional climatic forces created inhospitable conditions for reef growth, contributing to the observed hiatus and reduced reef flat accretion during the late Holocene (∼2 ka to present). • We report the lowest Holocene sea level highstand for the south eastern Brazilian region. • Two relative sea level oscillations identified at ∼3.7 ka and 2 ka respectively. • Hiatus in reef flat growth identified from 3.7 to 2.5 ka. [ABSTRACT FROM AUTHOR]

The hydromagnesite–magnesite playas near Atlin, British Columba, Canada are unique Mg-carbonate depositional environments that have formed at Earth's surface since the end of the last deglaciation. This study elucidates the mechanisms, pathways, and rates of magnesite (MgCO 3) formation in these near-surface environments, which are challenging to study in short-duration laboratory experiments because magnesite precipitation is extremely slow at low temperature. The Atlin playas, having formed over millennia, contain abundant magnesite as well as a suite of other Mg- and Ca-carbonate minerals. Mineralogical and textural evidence demonstrate that hydromagnesite [Mg 5 (CO 3) 4 (OH) 2 ·4H 2 O] forms at least in part through transformation of more hydrated phases, e.g., lansfordite (MgCO 3 ·5H 2 O). Deposition of these hydrated Mg-carbonate minerals is limited by the evaporative flux, and thus, is effectively transport-controlled at the scale of the playas. Magnesite is a spatially distinct phase from hydromagnesite and its crystal morphology varies with depth indicating variable crystal growth mechanisms and precipitation rates. Particle size distributions and mineral abundance data indicate that magnesite formation is nucleation-limited. Furthermore, mineralogical data as well as stable and radiogenic isotope data support magnesite formation starting after the majority of hydromagnesite had been deposited likely resulting from long induction times and slow precipitation rates. Hydrated Mg-carbonate minerals precipitate relatively rapidly and control pore water chemistry while magnesite remains highly supersaturated, and thus, is reaction-controlled. This difference in controlling regime allows for magnesite abundance to increase over time without the loss of hydromagnesite such as through its transformation, which the data also does not support. We estimate rates of magnesite formation (nucleation + crystal growth) in the range of 10−17 to 10−16 mol/cm2/s over approximately 8000 years. This study helps to elucidate the geochemical conditions needed to form Mg-carbonate minerals in ancient and modern sedimentary environments and provides insights into facilitating long-term storage of anthropogenic CO 2 within Mg-carbonate minerals. [ABSTRACT FROM AUTHOR]

Unambiguous identification of biosignatures on Mars requires access to well-characterized, long-lasting geochemical standards at the planet’s surface that can be modified by theoretical martian life. Ordinary chondrites, which are ancient meteorites that commonly fall to the surface of Mars and Earth, have well-characterized, narrow ranges in trace element and isotope geochemistry compared to martian rocks. Given that their mineralogy is more attractive to known chemolithotrophic life than the basaltic rocks that dominate the martian surface, exogenic rocks (e.g., chondritic meteorites) may be good places to look for signs of prior life endemic to Mars. In this study, we show that ordinary chondrites, collected from the arid Australian Nullarbor Plain, are commonly colonized and inhabited by terrestrial microorganisms that are endemic to this Mars analogue site. These terrestrial endolithic and chasmolithic microbial contaminants are commonly found in close association with hygroscopic veins of gypsum and Mg-calcite, which have formed within cracks penetrating deep into the meteorites. Terrestrial bacteria are observed within corrosion cavities, where troilite (FeS) oxidation has produced jarosite [KFe 3 (SO 4 ) 2 (OH) 6 ]. Where terrestrial microorganisms have colonized primary silicate minerals and secondary calcite, these mineral surfaces are heavily etched. Our results show that inhabitation of meteorites by terrestrial microorganisms in arid environments relies upon humidity and pH regulation by minerals. Furthermore, microbial colonization affects the weathering of meteorites and production of sulfate, carbonate, Fe-oxide and smectite minerals that can preserve chemical and isotopic biosignatures for thousands to millions of years on Earth. Meteorites are thus habitable by terrestrial microorganisms, even under highly desiccating environmental conditions of relevance to Mars. They may therefore be useful as chemical and isotopic “standards” that preserve evidence of life, thereby providing the possibility of universal context for recognition of microbial biosignatures on Earth, Mars and throughout the solar system. [ABSTRACT FROM AUTHOR]

Relative Sea Levels (RSLs) derived primarily from marine bivalves near Petermann Glacier, NW Greenland, constrain past regional ice-mass changes through glacial isostatic adjustment (GIA) modeling. Oxygen isotopes measured on bivalves corrected for shell-depth habitat and document changing meltwater input. Rapid RSL fall of up to 62 m/kyr indicates ice loss at or prior to ∼9 ka. Transition to an RSL stillstand starting at ∼6 ka reflects renewed ice-mass loading followed by further mass loss over the past few millennia. GIA simulations of rapid early RSL fall suggest a low regional upper-mantle viscosity. Early loss of grounded ice tracks atmospheric warming and pre-dates the eventual collapse of Petermann Glacier's floating ice tongue near ∼7 ka, suggesting grounding zone stabilization during early phases of deglaciation. We hypothesize mid-Holocene regrowth of regional ice caps in response to cooling and increased precipitation, following loss of the floating shelf ice. Remnants of these ice caps remain present but are now melting. • First use of stable isotopes in marine bivalves to correct subsurface habitat depths yielding sea-level index points. • Rapid RSL fall in NW Greenland indicates rapid loss of terrestrial ice at or prior to 9 ka, predating collapse of Petermann Glacier's floating ice tongue. • RSL stillstand in NW Greenland at ∼6 ka reflects renewed ice-mass loading in the neoglacial period. • Implications: o Upper mantle viscosities in NW Greenland are lower than currently assumed in GIA models. o GIA response in NW Greenland reflects complex ice history and models should include the evolution of local ice caps. [ABSTRACT FROM AUTHOR]

Abstract: Fish otoliths from the Willandra Lakes Region World Heritage Area (south-western New South Wales, Australia) have been analysed for oxygen isotopes and trace elements using in situ techniques, and dated by radiocarbon. The study focused on the lunettes of Lake Mungo, an overflow lake that only filled during flooding events and emptied by evaporation, and Lake Mulurulu, which was part of the running Willandra Creek system. Samples were collected from two different contexts: from hearths directly associated with human activity, and isolated surface finds. AMS radiocarbon dating constrains the human activity documented by five different hearths to a time span of less than 240 years around 19,350 cal. BP. These hearths were constructed in aeolian sediments with alternating clay and sand layers, indicative of fluctuating lake levels and occasional drying out. The geochemistry of the otoliths confirms this scenario, with shifts in Sr/Ca and Ba/Ca marking the entry of the fish into Lake Mungo several years before their death, and a subsequent increase in the δ18O by ∼4‰ indicating increasing evaporation of the lake. During sustained lake-full conditions there are considerably fewer traces of human presence. It seems that the evaporating Lake Mungo attracted people to harvest fish that might have become sluggish through oxygen starvation in an increasingly saline water body (easy prey hypothesis). In contrast, surface finds have a much wider range in radiocarbon age as a result of reworking, and do not necessarily indicate evaporative conditions, as shown by comparison with otoliths from upstream Lake Mulurulu. [Copyright &y& Elsevier]

Abstract: We provide geochemical analyses and grain size data for a clearly layered, 80cm thick sedimentary deposit close to a roof collapse in Blanche Cave near Naracoorte in SE South Australia. This deposit contains aeolian material deposited between ∼40ka and 14kacalBP and which yields airborne sediments spanning the Last Glacial Maximum, a period of time with little information for the Australian continent. The deposit also contains abundant vertebrate fossil material derived from owl pellets, accumulation and pitfall entrapment. Below the studied profile, large vertebrate remains are found but are not discussed here. No Holocene sedimentation occurred at the site examined in the cave, and the top of the sequence is capped with a layer that has been anthropologically disturbed and contains exotic Pinus pollen. Chronologies of the deposit were obtained using two dating techniques: single stage accelerator mass spectrometer (SSAMS) 14C analysis of 23 charcoal samples and optically stimulated luminescence (OSL) dating of quartz from 6 sediment samples. The 14C chronology is preferred to describe the history of the deposits since the OSL chronology, which consistently overestimates the associated radiocarbon dates, may be inaccurate due to complexities in calculating dose rates, and may in addition represent the timing of sediment deposition through the cave opening rather than sediment transport to the deposit site. Morphological analysis of single quartz grains and grain size analysis indicate different provenance that is confirmed through the geochemical analyses of bulk sediment. Major elements were measured by X-ray Fluorescence (XRF), trace and rare earth elements by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA ICP-MS), and Neodymium isotopic ratios were obtained using a Thermal Ionisation Mass Spectrometer (TIMS). Our results indicate that the aeolian material deposited in Blanche Cave over the 40–14kacalBP period originated from different sources across South Australia, although Nd isotopes clearly indicate a close association with sediments of the Kanmantoo Group outcropping along the eastern portion of the Mount Lofty Ranges and the Padthaway Ridge further south, both being located to the NW and NNW of the cave. During the latter part of Marine Isotope Stage 3, conditions were wetter and windblown sediment came from the coastal region just north and south of the Coorong Lagoon, with winds originating from the north-northwest. At that time, woody taxa appear to have vegetated the landscape. During the drier phases, especially the Last Glacial Maximum, sediment came from further inland, thus suggesting a different predominant wind direction, more from the northwest. The deglaciation saw material originating from a more northerly direction. [Copyright &y& Elsevier]