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Dental enamel represents an important mineralized archive of an individual's early life. Previously, isotopic (Ca) or trace element ratios (Sr/Ca, Ba/Ca) have been used to reveal dietary and weaning histories, although few studies have utilized both proxies to evaluate the respective results. Here we report histologically-defined, spatially-resolved Ca-isotope (laser-cut & TIMS) and trace element ratio (Sr/Ca, Ba/Ca; LA-ICPMS) profiles along the enamel-dentine-junction in three deciduous dental crowns of three early twentieth century Italian infants (Modern-22, 27, 29). Modern-27 and Modern-29 display overall similar patterns of Ca-isotope variation and reflect an overall increase of >1.0‰ in δ44/40Ca across and after birth. Whilst the Sr/Ca and Ba/Ca signals of Modern-27 suggest a mixed breast-formula feeding, the two elemental proxies in Modern-29 hint at nearly exclusive breastfeeding until ∼4 months, followed by introduction of formula. A ∼0.5‰ δ44/40Ca decrease across and after birth together with Sr/Ca ratios in Modern-22 suggest a dominant breastfeeding history for the first ∼5–8 months. Enamel Ca-isotope data alone are not sufficient to distinguish between breastfed or formula-fed infants. In addition, Ca-isotope profiles in deciduous enamel suggest a connection between prominent physiological stress like birth and negative Ca-isotope excursions, underlining the physiological overprint of Ca-isotope signatures. [ABSTRACT FROM AUTHOR]

The ratio of sodium to calcium in the shells of foraminifera (Na/Cashell) has been experimentally calibrated as a proxy for past ocean Ca concentrations (Hauzer et al., 2018, https://doi.org/10.1016/j.epsl.2018.06.004). In parallel, it has been suggested that Na/Cashell could be used as a proxy for paleo‐salinity. In this study, we determined the extent to which foraminiferal Na/Ca (and other elements) change with salinity for the shallow‐dwelling large benthic foraminifer Operculina ammonoides, an extant relative of the abundant Eocene Nummulites. The culture experiment was conducted under four salinities between 33 and 43 psu. Shell chemistry was measured by LA‐ICPMS with the newly precipitated CaCO3 identified by a 135Ba‐spike added to the experimental seawater. Na/Cashell, Mg/Cashell and Li/Cashell in O. ammonoides increased slightly with salinity, while Sr/Cashell showed no resolvable change. The change in Na/Cashell due to salinity was small (∼1.4%/psu) compared to the changes in this ratio caused by varying seawater calcium concentrations (Casw) with a sensitivity of ∼5%/(mmol kg−1) Casw. Moreover, the change in salinity in most regions of the past open oceans is minor compared to the large secular variations in Casw during the Phanerozoic (10–40 mmol kg−1). Thus, if at all, paleo‐salinity may be reconstructed based on Na/Cashell only for samples younger than Casw residence time (∼1 Myr). Furthermore, both regional and global changes in ocean salinity over geological time do not pose a significant complication for the use of Na/Cashell as a proxy for past changes in seawater calcium concentrations. Plain Language Summary: The ratio of sodium to calcium (Na/Ca) in the shells of foraminifera (single‐celled marine organisms) was previously shown to be a reliable proxy for calcium concentrations in the past oceans (Hauzer et al., 2018, https://doi.org/10.1016/j.epsl.2018.06.004). In this study, we examined experimentally the variations in Na/Ca under a range of seawater salinities. We find that there is a weak correlation between Na/Ca and salinity, but this variation is very small compared to the effect of varying seawater calcium concentrations. Therefore, Na/Ca can be used to reconstruct past seawater Ca concentrations and with it that of other conservative elements in the past ocean, as well as improving the accuracy of trace element paleothermometry. Key Points: Variations in foraminiferal sodium to calcium (Na/Ca) with salinity do not compromise the use of this ratio as a proxy for past seawater calcium concentrationsSalinity over the range ∼10 psu slightly affects the incorporation of Mg and to a lesser degree, of NaNa/Cashell in benthic foraminifera may be used as a salinity proxy within timescales shorter than ∼1 Myr [ABSTRACT FROM AUTHOR]

The process by which foraminifera precipitate calcite from seawater has received much attention, in part because a mechanistic basis for empirical calibrations between shell chemistry and environmental parameters is desirable given their widespread application in palaeoceanography. The incorporation of fluorescent membrane-impermeable molecules into the shell demonstrates that seawater, transported by vacuolisation, is present at the site of calcification. However, recent discussion has focused on whether the calcium required for chamber formation is sourced predominantly by transmembrane Ca transport (TMT), with seawater vacuolisation playing a passive role, or vice versa. This debate has arisen in part because of the need to explain the low Mg/Ca ratio of most foraminifera compared to inorganic calcite. Here, we present trace element data of Operculina ammonoides and Globigerinoides ruber , a high-Mg shallow benthic, and low-Mg planktonic species respectively, cultured under variable seawater carbonate and elemental chemistries. We find that Mg incorporation in high and low-Mg species is characterised by an opposite response to the carbonate system, demonstrating that the negative relationship between Mg/Ca and pH or CO 3 2 - in several low-Mg foraminifera is not an intrinsic feature of calcite precipitation. Therefore, any biomineralisation model must be able to explain why the mechanism by which seawater Mg/Ca is reduced is impacted by the carbonate system. Moreover, we show that trace element incorporation in G. ruber is consistent with Rayleigh fractionation from unmodified seawater except for Mg-removal, but in very poor agreement with a biomineralisation site [Ca] substantially elevated above that of seawater as required by the TMT hypothesis. In addition, any biomineralisation model must explain the nonlinear relationship between seawater and shell Mg/Ca, and the large number of seawater vacuoles observed in some species. Although there are important inter-species differences in biomineralisation, evident from the observed range of shell Mg/Ca ratios, we argue that these differences are mechanistically related to the degree of Mg exclusion prior to chamber formation. Indeed, whilst our data for both low-Mg and high-Mg species are consistent with biomineralisation via ions sourced through seawater vacuolisation, it is difficult to reconcile many of these observations with a model based on significant transmembrane Ca transport. [ABSTRACT FROM AUTHOR]

Abstract: A new add-on package (LAICPMS) for the R language for statistical computing is presented, which greatly facilitates data reduction and visualisation (single tracks and 2D element maps) of laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) data. The package determines many input parameters automatically and is easy to use. We present major and trace element distribution maps of natural calcite samples, processed using LAICPMS. Data processing from raw data to presented graphics takes only a few minutes. The empirical cumulative density function (ECDF) is used for optimised colour coding of the maps rather than linear or logarithmic scale, making a maximum of element-specific detail visible. For preprocessing, several different smoothing algorithms were evaluated and can be chosen by the user; for the presented data, a simple running median/running average was chosen. Typical data analysis is performed via short, easy-to-understand script files, and results can be used for further analyses within R. Owing to other R add-on packages utilised, the results can be output either numerically or as high-quality graphics in a wide range of file formats. Inheriting from its host environment R, the package is open-source software and freely available for all major computer platforms. [Copyright &y& Elsevier]

Recent advances in spatially-resolved in-situ geochemical analysis enabled recognizing daily variability in B, Mg, Sr and Ba within bivalve shells of the genus Tridacna (e.g. Sano et al., 2012; Warter and Müller, 2017). However, the causes for such daily chemical variations are not fully understood. We carried out laboratory culture experiments to investigate the effect of varying temperatures and light levels on organism physiology and shell geochemistry of the giant clam Tridacna crocea at daily time-resolution. We find that both temperature and light strongly influence shell growth rates. Besides demonstrating light enhanced calcification, we also observe growth inhibition during culture in continuous darkness. ‘Ultra-high resolution’ LA-ICP-MS analysis (Warter and Müller, 2017) in tandem with 135 Ba-labelling allows both to identify newly secreted, cultured aragonite and investigate its trace elemental composition at (sub)daily resolution (B/Ca, Mg/Ca, Sr/Ca, Ba/Ca). Overall, average Element/Calcium (El/Ca) ratios reveal an inverse relation with temperature and light. Strikingly, an increasing trend in all El/Ca ratios is observed in the direction of shell growth, which is interpreted to be metabolically-controlled, possibly related to organism ‘stress’. Daily, cyclic trace element variability can be clearly resolved at ~ 5–15 μm in relatively fast growing shells, which experienced a diurnal light cycle but constant temperatures. We conclude that light (but not temperature) is the primary controlling factor responsible for daily trace element variability. We further demonstrate that high El/Ca ratios correspond to growth during night time, i.e. low light intensities, corroborating field observations by Sano et al. (2012). Yet, because light levels were kept constant during night and day, respectively, light intensity cannot account for the entire range of the El/Ca variability. We hypothesize that Tridacna physiology and biochemistry is controlled by a circadian rhythm, initiated by the external factor light, but endogenously mediated by the giant clam and/or its photosynthetic symbionts. [ABSTRACT FROM AUTHOR]

We investigated the mobility pattern of an Upper Palaeolithic woolly mammoth (Mammuthus primigenius) from the Kraków Spadzista site in southern Poland, one of the largest mammoth bone accumulations in Europe. We conducted in situ laser ablation (MC-) ICPMS Sr isotopic and trace element concentration measurements accompanied by spatially-resolved oxygen isotope measurements of dental enamel on a last upper molar tooth (M6). Our study documents excellent preservation of in vivo geochemical and isotopic records and reveals recurring changes in 87Sr/86Sr that oscillate between two endmembers and correlate with analogous variations in δ18O, as well as U and Sr concentrations. The observed periodicity corresponds to annual cycles of enamel mineralization as revealed by enamel histology and documents up to 11 years of woolly mammoths' life in a single dental plate. The high degree of correlation between the duration of enamel mineralization and the Sr and O isotopic records suggests that the mammoth migrated between two areas of distinct Sr isotopic composition as well as characteristic U and Sr concentrations, presumably forced by seasonal food availability. The mammoth grazed in southern Poland in winter time as indicated by lower δ18O values and likely moved 250–400 km northwards to the Polish midlands during summer. This migration pattern remained stable for at least 12–13 years of the animal's adult life as archived in this molar tooth. Our study documents a fixed mobility behaviour of an adult mammoth some 10,000 years before the Last Glacial Maximum. • Histology of woolly mammoth molar indicates enamel mineralization over 12–13 years. • High resolution Sr and O isotopes record repetitive, annual composition changes. • Woolly mammoth from Kraków-Spadzista site migrated seasonally for 250–400 km. [ABSTRACT FROM AUTHOR]

New U-Pb zircon ages and geochemistry from the eastern Kédougou-Kéniéba Inlier are presented and integrated with published data to generate a revised tectonic framework for the westernmost Birimian terranes. The Falémé Volcanic Belt and Kofi Series are highly prospective, hosting several multi-million ounce gold deposits and a significant iron ore resource, but remain under-researched. It is therefore important to constrain the fundamental geological setting. The igneous rocks of the eastern Kédougou-Kéniéba Inlier are dominantly of high-K calc-alkaline affinity, with fractionated REE patterns and negative Nb-Ta anomalies. The plutonic rocks in the Falémé Belt are dioritic to granodioritic in composition, with moderately fractionated REE patterns and metaluminous A/CNK signatures. Felsic, peraluminous granite stocks, dykes and plutons with fractionated REE patterns and negative Eu, Ti and P anomalies intruded both the Falémé Belt and Kofi Series. Albitisation masks the affinity of some units, although use of the Th-Co diagram shows that prior to albitisation, all igneous units belonged to the high-K calc-alkaline series. New U-Pb age data for the Boboti and Balangouma plutons indicate crystallisation at 2088.5 ± 8.5 Ma and at 2112 ± 13 Ma, respectively. Inherited zircons in the Boboti pluton indicate magmatic activity in the Falémé Belt at 2218 ± 83 Ma coincided with the oldest dated units in the Mako Belt to the West. Systematic changes in Dy/Yb, Sm/La, Nb/Zr, Rb concentration, Eu-anomaly and ɛ Nd t over ∼200 Ma reveal that the tectonic setting in the KKI evolved from a volcanic island arc environment to an active continental margin. Crustal thickening, as a result of a shift to collisional tectonic setting, combined with magmatic differentiation, led to the generation of peraluminous, granitic melts with a significant crustal component. A small suite of more basic intrusive and extrusive rocks on the eastern margin of the Dialé-Daléma basin are highly metaluminous and display limited LILE enrichment, with normalised HREE values close to unity. The Daléma igneous rocks may have formed in an extensional back arc, related to the arc system. [ABSTRACT FROM AUTHOR]

Abstract: We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM–metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ∼11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7–8. We find that NOM–metal(aq) complexes on the boundary between colloidal and dissolved (∼1nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM–metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (K d) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (f m). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic K d values and field measurements for metal partitioning into calcite occur where [free metal]≪[total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where f m ≈0, apparent inorganic K d app values are also ≈0, but the true partition coefficient (K d actual) is significantly higher. Importantly, the K d of NOM–metal complexes [organic carbon–metal ratio) approaches 1 for the most stable aqueous complexes, as is shown here for Co, but has values of 24–150 for V, Ni and Cu. This implies that ternary surface complexation (metal–ligand co-adsorption) can occur (as for NOM–Co), but is the exception rather than the rule. We also demonstrate the potential for trace metals to record information on NOM composition as expressed through changing NOM–metal complexation patterns in dripwaters. Therefore, a suite of trace metals in stalagmites show variations clearly attributable to changes in organic ligand concentration and composition, and which potentially reflect the state of overlying surface ecosystems. [Copyright &y& Elsevier]

The isotopic composition and abundance of trace elements in skeletal remains are often used for paleobiological and paleoecological reconstructions. Increasing attention is being paid to dental enamel as the most resilient tissue, but its pristine biogenic signature is obscured to varying degrees by secondary mineralization and diagenesis. We investigated these effects combining histomorphometry with the Sr isotope and trace element distribution in an Upper Paleolithic woolly mammoth molar using laser ablation (MC) ICPMS. We document a 12-year continuous record of seasonal changes in 87Sr/86Sr, Li, Pb and U whose distribution pattern follows incremental enamel growth features of the secretion stage of amelogenesis. Other elements are affected by enamel maturation proceeding along the Retzius lines with a decrease in uptake of Rb, Sr, Ba and/or Mg, an increase in uptake of Mn, and considerable enrichment of Zn. The Sr/Ba ratio is consistent with the seasonal pattern of the secretion stage, indicating a short time gap between the two mineralization phases, estimated to be no more than a few months. The maturation front determined by multi-element 2D mapping penetrates, locally, as far as the inner enamel but generally does not affect the region nearest the enamel-dentine junction, making this the optimal zone for obtaining accurate biogenic data. This allowed the preservation of seasonal fluctuations in Zn and Mg, absent in the regions affected by maturation. We interpret the seasonality as the result of changes in diet and metabolism during cold and warm periods that likely accompanied mammoth migration, as suggested by the parallel changes in the Sr isotopic composition. Diagenesis affected K, Mg and Mn, but only in a narrow zone at the contact with the cementum. The dentine is diagenetically altered but still preserves relics of seasonal compositional cycles, while the cementum is completely equilibrated with the depositional environment. [Display omitted] • Histomorphometry of a woolly mammoth dental plate enamel documents 12 years record. • In situ Sr isotopes and trace element abundance measurements show seasonal changes. • Secretion stage 87Sr/86Sr, Li, Pb and U distribution is unaffected by maturation. • 2D Sr/Ba mapping reflects maturation process. Seasonal variations are due to changes in diet, probably linked to migration. [ABSTRACT FROM AUTHOR]

Large multivariate trace element datasets produced by LA-ICP-MS speleothem analysis can pose difficulties for analysis and interpretation. Processes acting on various timescales and magnitudes affect trace element concentrations, and deconvolving the most important controls is often complex. Here Principal Component Analysis (PCA) is applied to identify the modes and timings of variation which best explain the overall variability in an exceptionally high-resolution (10 μm vertical resolution) multivariate trace element record produced by LA-ICP-MS from a modern (1979–2001) Belizean stalagmite with excellent age control. Principal Component 1 (PC1) in this dataset is defined by a weak correlation between multiple elements, and may reflect non-carbonate material incorporated within the speleothem. Elevated PC1 scores in ATM-7 occur following regional volcanic eruptions with ash clouds extending over the cave site, as demonstrated using NASA remote sensing data from the Total Ozone Mapping Spectrometer and HYSPLIT trajectory modelling. Spikes in PC1 occur at the beginning of the wet season, and this may reflect a seasonal flushing event that transports volcanogenic material through the karst and incorporates it within the speleothem. Our results suggest that PCA can simplify exploration of large laser ablation datasets, and that PCA is a valuable tool for identifying the dominant controls on stalagmite trace element chemistry. Future studies should evaluate how transferable this technique is to other sites with different environmental conditions where volcanic ashfall has occurred. This research potentially adds tephrochronology to the stalagmite dating toolkit or, conversely, opens the door to using stalagmites to identify previously unknown or uncertainly dated eruptions. [ABSTRACT FROM AUTHOR]

Precisely-dated, high-resolution stable isotope and trace element data from a stalagmite from La Garma Cave, northern Spain, reveal several stages of distinct climatic variability along the northern Iberian Atlantic margin, and provide new constraints on the latitude of North Atlantic westerlies during the Younger Dryas Event (YD). Westerly wind position (reconstructed using sub-annually resolved Mg data as a proxy for sea spray contributions associated with wind strength at this coastal cave site) during the early YD (12.85–12.15 kyr) oscillated meridionally, resembling the decadal-scale component of the modern North Atlantic Oscillation (NAO). Northward repositioning of westerly storm tracks over northern Iberia began at ∼12.15 kyr, consistent with other high-resolution wind proxy reconstructions from central and northern Europe, but occurred more gradually nearer the Atlantic margin. From ∼12.15 kyr to the YD termination, atmospheric circulation resembled a persistently positive NAO, with westerlies reaching their maximum northward extent at 11.8 kyr (reflected by a Mg concentration minimum at this time). Air temperature (reflected by our δ 18 O data) and Iberian wind strength were predominantly coupled throughout the YD suggesting that temperature modulated sea-ice extent, and consequently controlled westerly wind latitude. However our data suggest that abrupt warming at 12.1 kyr was followed by much more gradual northward shifts in westerly position, and that a lag existed between the warming and sea-ice retreat. This gradual return of the westerlies to the north beginning at 12.1 kyr is consistent with inferred changes in wind strength at other European sites. Additionally, atmospheric circulation inferred from our northern Iberian wind strength proxy record generally tracked low-frequency meridional shifts in Intertropical Convergence Zone position, corroborating past research that suggested closely coupled low- and high-latitude atmospheric teleconnections over this period. [ABSTRACT FROM AUTHOR]

Abstract: The Sólheimar ignimbrite was one of the largest eruptions from the Katla caldera (Iceland) and is important for tephra studies in the North Atlantic because of its possible linkage with the Vedde Ash, a compositionally bimodal tephra layer used for correlation of sedimentary records in the North Atlantic and Northern Europe. The composition of the Sólheimar ignimbrite extends from rhyolite to basaltic-icelandite, a trend that defines a coherent magma mixing line. Mixing is evident both in mingled textures seen in hand specimens and thin sections and as binary mixing trends in major and trace element and 87Sr/86Sr isotopes of the volcanic glasses. The Sólheimar rhyolite is slightly more radiogenic than the basaltic-icelandite in terms of Sr isotopes, which is inconsistent with generation of the rhyolite by fractionation of the basaltic-icelandite. Alternatively, the Sólheimar rhyolite may have been produced by partial melting of Icelandic crust. Major and trace element modelling indicates that partial melting of Icelandic tholeiite does not replicate the observed rhyolite composition, in particular K2O is significantly lower in the modelled melt. However, partial melting of Katla alkali basalt does produce a comparable melt. We suggest a two-stage model in which 30–40% melting of basalt generated a dacitic magma which underwent subsequent ∼30% fractionation of the observed phenocryst phases (feldspar, clinopyroxene, spinel and FeTi oxide) form rhyolite. The eruption of the Sólheimar ignimbrite was triggered by the intrusion of basaltic-icelandite magma, which mixed with resident rhyolite magma during eruption. The Sólheimar ignimbrite has been linked to the Vedde Ash (), a compositionally bimodal tephra layer used to link sedimentary records in the North Atlantic and Northern Europe. Despite the importance of the Vedde Ash in late Quaternary studies, its provenance remains equivocal. We demonstrate that Vedde rhyolite glasses share the same major and trace element chemistry as the Sólheimar rhyolite, carrying the implication that these deposits may be produced by the same eruption. However, the Sólheimar ignimbrite lacks the basaltic component that is sometimes associated with rhyolitic shards of the Vedde Ash at far distal locations, therefore this correlation cannot be confirmed. [Copyright &y& Elsevier]

Several stalagmite records have yielded important but discontinuous insights into northern Iberian climate since the Last Glacial. Here we present the first continuous Iberian stalagmite-based reconstruction of climate since the Bølling-Allerød interstadial, from a single stalagmite sample (GAR-01 from La Garma Cave, Cantabria). The ∼13.5 ka GAR-01 record provides the opportunity for replication, continuation, and aggregation of previously published records from northern Spain. The GAR-01 record reveals shifts in oxygen isotope ratios that are inexplicable by appealing to a single control (i.e., exclusively temperature, rainfall amount, etc.). Herein we explore the potential role of rainfall and temperature seasonality shifts on the new δ18O record using a simple Monte Carlo approach to estimate the seasonal distribution of rainfall and the annual temperature range at 100-year timeslices across the record. This model is corroborated by intervals of monthly-resolved laser ablation trace element data, providing glimpses into past Iberian seasonality shifts. The most salient features of the modelled results include extremely dry Younger Dryas winters (∼12.9–11.6 ka BP) and several intervals during the mid-Holocene with almost no summer rainfall (e.g., at 4.2 and 9.0 ka BP). By 1.6 ka BP, a near-modern rainfall seasonality was established. According to the modelling results, seasonal rainfall and temperature distribution variability can account for 95% of the record. The model presented here provides a new tool for extracting critical missing seasonality information from stalagmite δ18O records. Intervals where the model does not converge may represent transient climate anomalies with unusual origins that warrant further investigation. • First continuous stalagmite reconstruction of North Iberian palaeoclimate spanning the Younger Dryas and Holocene. • The ∼13.5 ka GAR-01 record provides replication, continuation, and aggregation of existing regional stalagmite records. • N. Iberian stalagmite δ18O records largely covary but with a δ18O offset that reflects cave altitude and inland position. • Using a simple Monte Carlo approach, shifts in GAR-01 δ18O are explained by changing temperature and rainfall seasonality. • Monthly-resolved LA-ICPMS data provide glimpses into past Iberian seasonality shifts and corroborate the model. [ABSTRACT FROM AUTHOR]