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Lithological heterogeneity is a widely accepted feature of the Earth’s mantle, with recycled crustal material accounting for a significant part of heterogeneity in ocean island basalt (OIB) geochemistry. Fe isotopes have been used to link geochemical heterogeneity in OIB sources to distinct mantle lithologies due to their mineral-specific equilibrium fractionation effects, or their composition, such as incorporation of kinetically-fractionated core liquids entrained from the core-mantle boundary. Here we present Fe isotope data for Samoan shield, and Azores volcanoes, together with a combined phase-equilibria and equilibrium mineral-melt isotope fractionation model. These OIB lavas allow us to study the roles of core-derived and recycled mantle components in generating heavy δ57Fe melts. Heavy δ57Fe correlates with radiogenic isotope signatures of enrichment by a crustal component and not with Fe/Mn or any indicator of core involvement. However, single-stage melting of a MORB-like eclogitic pyroxenite cannot generate the heavy δ57Fe seen in Pitcairn, Azores, and rejuvenated Samoa lavas. Melts of a reaction-zone pyroxenite (commonly suggested to form part of the OIB source), derived from eclogite melts hybridised with peridotite, also fail to generate the heaviest Fe isotopic compositions seen in OIB. Instead, the generation of heavy δ57Fe melts in OIB requires: (1) processes that make subducted eclogite isotopically heavier than its pristine precursor MORB (e.g., hydrothermal alteration, metamorphism, sediment input); (2) lithospheric processing, such as remobilisation of previously frozen small-degree melts, or a contribution from lithospheric material metasomatised by silicate melts; and/or (3) melting conditions that limit the dilution of melts with heavy δ57Fe by ambient lower δ57Fe materials. No single process we consider can generate the heavy δ57Fe seen in the Azores, Pitcairn, and rejuvenated Samoan lavas. Therefore, it cannot be assumed that a pyroxenite lithology derived from recycled crustal material is the sole producer of heavy δ57Fe melts in OIB, nor can these signatures be related to contributions from the Earth’s core. Instead, the observation of heavy δ57Fe OIB melts cannot be ascribed to a unique source or process. This ambiguity reflects the multitude of processes operating from the generation of recycled lithologies through to their mantle melting: from MORB generation, its low temperature alteration, through mantle heterogeneity development and lithospheric processing, to eruption at ocean islands.

We present a new procedure for the separation and purification of Cu and Zn from geological samples. Our procedure employs a single pass, triple-stack column setup. The first column, filled with TRU resin (TrisKem International), quantitatively removes Fe and Ti from sample matrices. A second column, filled with Pre-filter resin (TrisKem International), removes organic compounds. Finally, a third column, filled with anion exchange resin (AG1-X8, 200-400 mesh, Bio-Rad), is used to separate Cu and Zn from the remaining matrix. Our procedure requires about 50% less acid volume than previously reported methods for Cu and Zn separation, thereby minimising analytical blanks and column running times. Copper and Zn stable isotope ratios were determined by a Thermo Neptune Plus MC-ICP-MS using Zn and Cu external normalisation, respectively, in addition to sample-standard bracketing (SSB) to correct for instrumental mass bias. We explore the inter-calibration of Cu and Zn isotope fractionation coefficients during analysis by measuring mixed Cu-Zn solutions with enhanced mass bias variation generated by varying sample gas flow rates. Our results demonstrate that this procedure is useful when variation in instrumental mass bias throughout analytical sequences is insufficient to inter-calibrate Cu and Zn fractionation coefficients.

Subduction zone systems are central to a multitude of processes from the evolution of the continental crust to the concentration of metals into economically viable deposits. The interplay between oxygen fugacity, sulfur saturation, fluid exsolution and fractionating mineral assemblages that gives rise to typical arc magma chemical signatures is, however, still poorly understood and novel geochemical approaches are required to make further progress. Here we examine a well-characterized suite of arc lavas from the Marianas (W. Pacific) for their stable Fe isotope composition. In agreement with previous work and mass balance considerations, contributions from sediments and/or fluids are shown to have negligible effect on Fe isotopes. Instead, we focus on disentangling processes occurring during basalt through dacite differentiation using a sample suite from the island of Anatahan. Anatahan whole rock Fe isotope compositions (δ57Fe) range from −0.05 ± 0.05 to 0.17 ± 0.03 (2 S.D.)‰. A fractionation model is constructed, where three distinct stages of differentiation are required to satisfy the combined major and trace element and isotopic observations. In particular, the sequestration of isotopically heavy Fe into magnetite and isotopically light Fe into sulfide melts yields important constraints. The data require that lavas are first undersaturated with respect to crystalline or molten sulfide, followed by the crystallisation of magnetite, which then triggers late sulfide saturation. The model demonstrates that the final stage of removal of liquid or crystalline sulfide can effectively sequester Cu (and presumably other chalcophiles) and that late stage exsolution of magmatic fluids or brines may not be required to do this, although these processes are not mutually exclusive. Finally, the new Fe isotope data are combined with previous Tl-Mo-V stable isotope determinations on the same samples. Importantly, the multi-valent transition metal stable isotope systems of Fe and V are decoupled by sulfide saturation, thus providing a potential tool to constrain its somewhat intractable timing. The observed decoupling of notionally redox-sensitive tracers underlines the caution required in the application of transition metal isotopes as direct redox proxies.

Iron formations (IFs) are important geochemical repositories that provide constraints on atmospheric and ocean chemistry, prior to and during the onset of the Great Oxidation Event. Trace metal abundances and their Mo-Cr-U isotopic ratios have been widely used for investigating ocean redox processes through the Archean and Paleoproterozoic. Mineralogically, IFs consist of three main Fe-bearing fractions: (1) Fe-Ca-Mg-Mn carbonates, (2) magnetite and/or hematite and (3) Fe-silicates. These fractions are typically fine-grained on a sub-μm scale and their co-occurrence in varying amounts means that bulk-rock or microanalytical geochemical and stable isotope data can be influenced by cryptic changes in mineralogy. Fraction specific geochemical analysis has the potential to resolve mineralogical controls and reveal diagenetic versus primary precipitative controls on IF mineralogy. Here we adapt an existing sequential extraction scheme for Fe-phases (Poulton and Canfield, 2005) to the high Fe-content in IF and the specific three-fraction mineralogy. We optimized the scheme for magnetite-dominated Archean IFs using samples from the hematite-poor Asbestos Hills Subgroup IF, Transvaal Supergroup, South Africa. Previously commonly-used hydroxylamine-HCl and dithionite leaches were omitted since ferric oxides are quantitatively insignificant in these IF samples. The acetate leach was tested at variable temperatures, reaction times and under different atmospheres in order to ensure that all micro-crystalline Fe-carbonates were effectively dissolved, resulting in an optimum extraction for 48 h at 50 °C under anoxic conditions. The dissolution of magnetite by NH4-oxalate was also tested, resulting in an optimum extraction for 24 h under an ambient atmosphere. Finally, a HF-HClO4-HNO3 leach was used to dissolve the residual silicate fraction which has to date not been considered in detail in IF. Accuracy of the extraction technique was generally excellent, as verified using 1) elemental recoveries, 2) comparison of major and trace element distributions against mineralogy and 3) comparison to results from microanalytical techniques. This study focuses on the distribution of three frequently used geochemical proxies in IF; U, Mo and Cr. Molybdenum abundances in the Kuruman and Griquatown IF are low and show an apparent correlation with mineralogical variability, as determined by the sequential extraction. This suggests that changes in bulk-rock mineralogy, rather than redox chemistry might significantly affect Mo stable isotopes. For Cr, a minor bulk-rock stratigraphic increase can be related to the oxide and silicate fraction. However, a positive relationship with Zr indicates that this was also controlled by detrital or volcanic ash input. Uranium is predominantly bound to the silicate fraction and shows clear correlations with Zr and Sc implying detrital reworking under anoxic conditions. The discrepant behaviour of these three proxies indicate that mineralogy should be taken into account when interpreting heterogeneous bulk-rock samples and that fraction specific techniques will provide new insights into the evolution of atmosphere and ocean chemistry.

© 2017 The Authors. Health Promotion Journal of Australia published by John Wiley & Sons Australia, Ltd on behalf of Australian Health Promotion Association Issue addressed: Foetal Alcohol Spectrum Disorder (FASD) includes a range of life-long impairments caused by alcohol exposure in utero. Health professionals are vital to preventing FASD but many are hesitant to discuss FASD with clients due to their need for additional resources to aid the conversation. This scan sought to identify the scope and gaps in publicly available FASD prevention and health promotion resources, and assess their cultural appropriateness for use among five key groups of Indigenous Australian people including: (i) pregnant women, (ii) women of childbearing age, (iii) grandmothers and aunties, (iv) men, and (v) health professionals. Methods: Relevant resources published 1995-2017 were identified through the Australian Indigenous HealthInfoNet, FASD organisation websites, grey literature, Google searches, and field experts. Results were screened by inclusion and cultural appropriateness criteria developed and piloted by the research team, and further screened by health professionals attending FASD training workshops. Results: 115 of the 2146 identified resources were eligible. Relevant resources were found for all five key groups; however, no resources were specifically designed for men, grandmothers or aunties. Conclusions: A range of high-quality, culturally appropriate resources were identified, however, health professionals attending the training workshops were not aware of their availability. Further resource development is suggested for men, grandmothers and aunties. So what?: Prioritisation of active dissemination and implementation strategies is suggested to increase awareness and use of future resource developments. The inclusion of a resource trial among health professionals is a recommended strategy to increase awareness and use of newly developed resources.

© 2016 John Wiley & Sons Ltd. To investigate health professionals' perspectives about factors that impede or facilitate cancer care for Indigenous people. Semi-structured interviews with 22 health professionals involved in Indigenous cancer care. Data were interpreted using an inductive thematic analysis approach. Participants presented their perspectives on a number of barriers and enablers to Indigenous cancer care. Barriers were related to challenges with communication, the health system and coordination of care, issues around individual and community priorities and views of cancer treatment and health professional judgement. Enablers to cancer care were related to the importance of trust and rapport as well as health care system and support factors. The findings highlighted the need for recording of Indigenous status in medical records and a coordinated approach to the provision of evidence-based and culturally appropriate cancer care. This could go some way to improving Indigenous patient's engagement with tertiary cancer care services.

From January to April 1986 all 21 Clinical Microbiology Laboratories in Wales took part in a survey to determine the prevalence of antibiotic resistance in Haemophilus influenzae. All isolates were collected and despatched to a central laboratory where identification was confirmed and antibiotic sensitivity tests repeated. One thousand four hundred and forty strains were available for analysis. Resistance was present in 128 (8.9%) to ampicillin, 23 (1.6%) to cefaclor, 28 (1.7%) to chloramphenicol, 282 (19.6%) to erythromycin, 43 (3.0%) to tetracycline, 90 (6.2%) to sulphonamide and 66 (4.6%) to trimethoprim. One hundred and twenty-one strains (8.4%) were beta-lactamase producers. Thirteen (0.9%) were resistant to four or more antibiotics and included one type b strain isolated from cerebrospinal fluid resistant to ampicillin, chloramphenicol, tetracycline, trimethoprim and sulphonamide. The prevalence of resistance to ampicillin and trimethoprim was higher than that recorded previously in two large studies elsewhere in the United Kingdom. Ampicillin resistance was more common in strains from hospital inpatients than those from general practice.

Mantle plume-related magmas typically have higher chalcophile and siderophile element (CSE) contents than mid-ocean ridge basalts (MORB). These differences are often attributed to sulfide-under-saturation of plume-related melts. However, because of eruption-related degassing of sulfur (S) and the compositional, pressure, temperature and redox effects on S-solubility, understanding the magmatic behavior of S is challenging. Using CSE data for oceanic plateau basalts (OPB), which rarely degas S, we show that many OPB are sulfide-saturated. Differences in the timing of sulfide-saturation between individual OPB suites can be explained by pressure effects on sulfur solubility associated with ascent through over-thickened crust. Importantly, where S-degassing does occur, OPB have higher CSE contents than S-undegassed melts at similar stages of differentiation. This can be explained by resorption of earlier-formed sulfides, which might play an important role in enriching degassed melts in sulfide-compatible CSE and potentially contributes to anomalous enrichments of CSE in the crust.

The geochemistry of global mantle melts suggests that both mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) sample lithological and temperature heterogeneities originating in both the upper and lower mantle. Recently, non-traditional stable isotopes have been suggested as a new tool to complement existing tracers of mantle heterogeneity (e.g., major and trace elements, radiogenic isotopes), because mineral- and redox-specific equilibrium stable isotope fractionation effects can link the stable isotope ratios of melts to their source mineralogy and melting degree. Here, we investigate five stable isotope systems (Mg-Ca-Fe-V-Cr) that have shown promise in models or natural samples as tracers of mantle temperature and/or lithological heterogeneity. We use a quantitative model, combining thermodynamically self-consistent mantle melting and equilibrium isotope fractionation models, to explore the behaviour of the isotope ratios of these elements during melting of three mantle lithologies (peridotite, and silica-excess and silica-deficient pyroxenites), responding to changes in mantle mineralogy, oxygen fugacity, temperature and pressure.We find that, given current analytical precision, the stable isotope systems examined here are not predicted to be sensitive to mantle potential temperature variations through equilibrium isotope fractionation processes. By contrast, source lithological heterogeneity is predicted to be detectable in some cases in the stable isotope ratios of erupted basalts, although generally only at proportions of > 10% MORB-like pyroxenite in the mantle source, given current analytical precision. Magnesium and Ca stable isotopes show most sensitivity to a garnet-bearing source lithology, and Fe and Cr stable isotopes are potentially sensitive to the presence of MORB-like pyroxenite in the mantle source, although the behaviour of Cr isotopes is comparatively under-constrained and requires further work to be applied with confidence to mantle melts. When comparing the magnitude and direction of predicted equilibrium isotopic fractionation of peridotite and pyroxenite melts to natural MORB and OIB data, we find that aspects of the natural data (including the mean Mg-Ca-Fe-V isotopic composition of MORB, the range of Mg-Ca isotopic compositions seen in MORB data, the mean Mg-Ca-Cr isotopic composition of OIB, and the range of Mg-V-Cr isotopic compositions in OIB data) can be matched by equilibrium isotope fractionation during partial melting of peridotite and pyroxenite sources -- with pyroxenite required even for some MORB data. However, even when considering analytical uncertainty on natural sample measurements, the range in stable isotope compositions seen across the global MORB and OIB datasets suggests that kinetic isotope fractionation, or processes modifying the isotopic composition of recycled crustal material such that it is distinct from MORB, may be required to explain all the natural data. We conclude that the five stable isotope systems considered here have potential to be powerful complementary tracers to other geochemical tracers of the source lithology of erupted basalts. However, continued improvements in analytical precision in conjunction with experimental and theoretical predictions of isotopic fractionation between mantle minerals and melts are required before these novel stable isotopes can be unambiguously used to understand source heterogeneity in erupted basalts.

The extent of lithological heterogeneity in the Earth’s convecting mantle is highly debated. Whilst the presence of pyroxenite in the mantle source regions of Ocean Island Basalts (OIBs) has traditionally been constrained using the minor-element chemistry of olivine phenocrysts, recent studies have shown that the Ni and Mn contents of primitive olivines are influenced by the conditions of mantle melting, as well as magma chamber processes. Nevertheless, constraining the lithological properties of the mantle is important due to it’s influence on the P-T path followed by solid mantle material during adiabatic ascent, as well as the density of upwelling mantle plumes. We have therefore explored the use of Fe-isotopes as a novel method of tracing lithological heterogeneity in the mantle source regions beneath plume-influenced segments of the global Mid-Ocean Ridge system as well as OIBs. We present new Fe-isotope (δ56Fe) and trace-element data for 26 basaltic glasses from the plume-influenced Galápagos Spreading Centre to investigate the relative roles of pyroxenite and peridotite in the mantle source region of oceanic basalts. Our data reveals significant heterogeneity in the Fe-isotope composition of the Galápagos Spreading Centre basalts (+0.05 - +0.25‰ δ56Fe), which correlates with key major- and trace-element parameters (e.g. CaO(8)/Al2O3(8), [La/Sm]n). Application of new models developed to calculate Fe-isotope fractionation during mantle melting, alongside Monte Carlo simulations for melting of a 2-component peridotite mantle, show that this variation cannot be caused by changes in melting processes and/or oxygen fugacity of a peridotitic mantle. Instead, our new δ56Fe data is best explained by variations in the proportion of isotopically-heavy pyroxenite-derived melt that contributes to the GSC basalts, and conclusively shows that lithological heterogeneity exists in the Galápagos mantle plume. Our findings have implications for the moderately-heavy δ56Fe compositions measured in plume-influenced basalts from the Society Islands, Rochambeau Ridges of the Lau back-arc basin, and the FAMOUS segment of the Mid-Atlantic Ridge, which we suggest may also represent contribution from pyroxenite-derived melts.

Young (61 Ma) unaltered picrites from Baffin Island, northwest Canada, possess some of the highest 3He/4He (up to 50 Ra) seen on Earth, and provide a unique opportunity to study primordial mantle that has escaped subsequent chemical modification. These high-degree partial melts also record anomalously high 182W/184W ratios, but their Sr-Nd-Hf-Pb isotopic compositons (including 142Nd) are indistinguishable from those of North Atlantic mid-ocean ridge basalts. New high precision Fe and Zn stable isotope analyses of Baffin Island picrites show limited variability with δ56Fe ranging from −0.03‰ to 0.13‰ and δ66Zn varying from 0.18‰ to 0.28‰. However, a clear inflection is seen in both sets of isotope data around the composition of the parental melt (MgO = 21 wt %; δ56Fe = 0.08 ± 0.04‰; and δ66Zn = 0.24 ± 0.03‰), with two diverging trends interpreted to reflect the crystallisation of olivine and spinel in low-MgO samples and the accumulation of olivine at higher MgO. Olivine mineral separates are significantly isotopically lighter than their corresponding whole rocks (δ56Fe ≥ −0.62‰ and δ66Zn ≥ −0.22‰), with analyses of individual olivine phenocrysts having extremely variable Fe isotope compositions (δ56Fe = −0.01‰ to −0.80‰). By carrying out modelling in three-isotope space, we show that the very negative Fe isotope compositions of olivine phenocryst are the result of kinetic isotope fractionation from disequilibrium diffusional processes. An excellent correlation is observed between δ56Fe and δ66Zn, demonstrating that Zn isotopes are fractionated by the same processes as Fe in simple systems dominated by magmatic olivine. The incompatible behaviour of Cu during magmatic evolution is consistent with the sulfide- undersaturated nature of these melts. Consequently Zn behaves as a purely lithophile element, and estimates of the bulk Earth Zn isotope composition based on Baffin Island should therefore be robust. The ancient undegassed lower mantle sampled at Baffin Island possesses a δ56Fe value that is within error of previous estimates of bulk mantle δ56Fe, however, our estimate of the Baffin mantle δ66Zn (0.20 ± 0.03‰) is significantly lower than some previous estimates. Comparison of our new data with those for Archean and Proterozoic komatiites is consistent with the Fe and Zn isotope composition of the mantle remaining constant from at least 3 Ga to the present day. By focusing on large-degree partial melts (e.g. komatiites and picrites) we are potenitally biasing our record to samples that will inevitably have interacted with, entrained and melted the ambient shallow mantle during ascent. For a major element such as Fe, that will continuosly participate in melting as it rises through the mantle, the final isotopic compositon of the magama will be a weighted average of the complete melting column. Thus it is unsuprising that minimal Fe isotope variation are seen between localities. In contrast, the unique geochemical signatures (e.g. He and W) displayed by the Baffin Island picrites are inferred to solely originate from the lowermost mantle and will be continuously diluted upon magma ascent.

A novel 76Se–78Se double spike allows for rapid and precise selenium isotope measurements in geological samples.

Phosphorus availability is considered a limiting factor in many scenarios for the origin of life. The concentration of P in environments of prebiotic interest will have been governed by the available mineral sources of P on the early Earth. A knowledge of early Earth P mineralogy and prevailing global and local environmental conditions is therefore needed to understand which scenarios for prebiotic chemistry are most plausible. Here, we review the plausible diversity of P-bearing phases at Earth’s surface during the emergence of life. We consider phases that were delivered by meteorites (exogenous phases), as well as those that developed solely as a result of Earth system processes (endogenous phases). We take into account the known formation conditions of individual phases, as well as the observed temporal distributions of P-bearing minerals found at Earth’s surface today. Our approach allows us to leverage what is known about changes in the Earth system in order to rule out the prebiotic relevance of many P-bearing phases. Meanwhile, we highlight a small number of phases that are of possible prebiotic relevance; specifically, exogenous schreibersite, merrillite, and apatite, and endogenous apatite, olivine, and glass. Prebiotic mineral-chemical scenarios can be formulated for each phase, with distinct requirements for the environmental and tectonic state of early Earth. We can therefore relate the plausibility of mineral-chemical scenarios to the nature of early Earth, bridging the fields of geoscience and prebiotic chemistry.