Hawaiian volcanoes belong to two geographically and geochemically distinct trends, the Loa and Kea trends. The cause of this dichotomy is still strongly debated. One of the prevailing hypotheses is ...that the two trends originate in the deep mantle where the Hawaiian mantle plume straddles two geophysically and geochemically distinct domains at the core‐mantle boundary (CMB). New high‐precision multi‐isotopic (Pb, Hf, Nd, and Sr) compositions of lavas from three key volcanoes, Lō‘ihi, Kohala, and Haleakalā, show transitional signatures between Loa and Kea compositions that call into question the degree of physical independence between the two trends. Statistical analysis of multi‐collector inductively coupled plasma mass spectrometer or triple‐spike Pb (n > 800) and Sr, Nd, and Hf data (n > 400) for shield tholeiites from the entire Hawaiian Islands (<5.5 Ma) identifies six unique geochemical groups, and for the first time, documents large‐scale heterogeneities in the Kea trend. The spatial orientation of the six geochemical groups shows that the bilateral zonation of the plume source at the CMB is gradational, and that the Hawaiian mantle plume periodically entrains large‐scale ephemeral geochemical heterogeneities on million‐year, regional timescales. These geochemical heterogeneities are stretched vertically during transit of the plume to the surface and are observed in the lavas from the Hawaiian Islands. These results provide evidence that the large low shear velocity province in the deep Pacific is thermochemical and highly heterogeneous.
Key Points
Six unique geochemical groups are identified by statistical analysis of isotopic data of Hawaii shield basalts
The spatial orientation of the six geochemical groups shows that the bilateral zonation of the plume source at the core‐mantle boundary is gradational
The large low shear velocity province in the deep Pacific is thermochemical and highly heterogeneous
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The Color Alteration Index (CAI) of conodont specimens is commonly used for identifying the maximum temperature to which units of sedimentary rock, particularly carbonates, have been heated. ...Observable color variations in these fossils are thought to be a result of the thermally-induced structural evolution of organic carbonaceous matter (CM). Such temperature history information is extremely valuable for applications in hydrocarbon exploration as well as for constraining other temperature-related geological processes in sedimentary systems. However, the identification of CAI depends on the qualitative visual assessment of color, which, along with a host of other potential complications, may yield inaccurate determinations of maximum temperature. Raman spectroscopy allows thermally-induced structural changes in CM to be quantified, and it has been used to estimate the thermal maturity in metasedimentary rocks for almost two decades. Here, we use Raman spectroscopy of carbonaceous material (RSCM) in conodont specimens and their Mississippian to Upper Triassic host rocks from British Columbia, Canada, to estimate maximum temperatures based on the transformation (structural reorganization) of disordered carbon to graphite. This study demonstrates that the maximum temperatures experienced by conodont specimens, as calculated from RSCM using the Iterative Fitting of Raman Spectra (IFORS) technique, correlate well with CAI but lie outside the suggested ranges in some instances. This may be due to complex thermal histories of these conodont specimens or the influence of diagenetic alteration, not thermal histories, on conodont color. We recommend the application of Raman spectroscopic analyses of CM in conodonts and their host rocks to obtain more confident, accurate, and precise estimations of maximum temperature that are independent of CAI.
•Raman response of carbonaceous material (CM) in conodonts allows calculation of max. temperature.•Raman temperature calculations are more precise and likely more accurate than if estimated with CAI.•Diagenetic alteration may cause discrepancies between CAI and Raman temperature estimates.•Higher variance in temperature estimates for high CAI conodonts may be due to degradation of CM.•Combining CAI and Raman provides more robust determinations of max. temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Archaeologists' access to analytical infrastructure has grown exponentially over the last two decades. This is especially the case for benchtop X-ray fluorescence (XRF) and portable XRF (pXRF) ...instruments, which are now practically commonplace in archaeological laboratories and provide users with a non-destructive and rapid means to analyze the elemental compositions of archaeological specimens. As XRF has become more accessible, the volume of analytical measurements available in archaeological datasets as well as the number and diversity of researchers participating in data collection have inherently increased. Those researchers, who have various levels of experience with the nuances of lithic sourcing procedures, are also often the ones attempting to interpret the elemental data they produce. While standardized analytical procedures have enabled inexperienced analysts to take accurate and reproducible XRF measurements, interpreting the resulting data is more difficult to convert and standardize with the same degree of user-friendliness. To address this challenge, we have bundled a series of statistical approaches and data exploration tools into an intuitive open-source graphical user interface designed to facilitate reproducible and robust outcomes during lithic sourcing studies. Our application, SourceXplorer, permits easy access to and exploration of numeric baseline data using a map interface while facilitating a guided interpretation of source affiliations for archaeological specimens (e.g., lithics) within any natural context using multivariate statistical analyses. We demonstrate SourceXplorer's functionality in relation to a complex archaeological challenge by examining evidence for the procurement and use of lithic material from previously undocumented toolstone source locations in southwestern British Columbia, Canada. We also provide open access to SourceXplorer, including both a deployed version of the application that can be used with any Internet browser and the packaged script, which can be run locally in the open-source R statistical programming environment.
•R Shiny application and package developed for guided and automated lithic sourcing.•Statistical tests and data exploration tools bundled into convenient map-based GUI.•Post-hoc tests facilitate the use of an exclusionary approach to sourcing studies.•Use any numeric data in any geographical context that has adequate baseline data.•Functionality shown via complex case study in Sts'ailes Coast Salish Territory.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The impacts of diagenesis on archaeological and palaeontological bone complicate investigations of in-vivo chemical and isotopic characteristics. Such bone is often pre-treated in an attempt to ...remove diagenetic alteration prior to trace element or isotopic analyses, although very few standardized approaches exist for evaluating pre-treatment effectiveness. In this pilot study, we characterize the diagenetic alteration and assess the impact of acetic acid chemical pre-treatment on the trace element and structural characteristics of four bones from Belgium, including an Early Medieval cremated bone from Broechem and three representative ‘old’ bones of different ages (ca. 40–130 ka) from the Late Pleistocene sedimentary sequence of Scladina Cave. Each bone was analyzed before and after acetic acid pre-treatment using the ‘Perio-spot’ technique and ‘Perios-endos’ profiles. We measured trace element concentrations with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and micro X-ray fluorescence spectroscopy (μXRF). Structural characteristics were investigated with Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). Our results indicate that chemical pre-treatment had little to no significant impact on the trace element content of the Early Medieval cremated bone, had the most impact on the youngest bone from Scladina Cave, and had less impact on the trace element content of two older bones from Scladina Cave. This suggests that the effectiveness of acetic acid chemical pre-treatment is greater for bones undergoing early diagenetic processes, has minimal impact on highly crystalline cremated bone, and may preferentially leach in-vivo signatures from bones undergoing later diagenesis. The weights of leachates removed from each bone also correspond well with their hypothetical diagenetic states, indicating that researchers could potentially assess the diagenetic state of bones by weighing the leachates produced during acetic acid pre-treatment. Therefore, our new approach may provide a valuable step toward effectively and consistently differentiating among in- and ex-vivo trace element signatures, and, by proxy, those of their isotopes, in archaeological and palaeontological bone.
•Diagenesis and impact of acetic acid pre-treatment investigated in ‘old’ and cremated bone•Acetic acid pre-treatment has little to no impact on trace element and structural characteristics of cremated bone•Impact of acetic acid pre-treatment is greatest for reactive ‘old’ bones undergoing early diagenetic processes•Acetic acid pretreatment may preferentially leach in-vivo signatures from recrystallized ‘old’ bone•Weights of dried-down leachates correspond with diagenetic state of ‘old’ bones
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study's aim was to compare biochar and steam activated biochar functionalized with iron for removal of selenium as selenate from solutions also containing nitrate and sulfate. The Fe-biochar ...composites were made impregnating iron (ferric nitrate) onto regular biochar (RB) and steam activated biochar (SAB), forming the Fe-biochar composites FeRB and FeSAB. Iron oxyhydroxide deposits were observed on the surface of FeRB using Raman spectroscopy analysis, but not on the FeSAB surface. Unmodified biochar samples did not remove selenium, as Se(VI), from solution, whereas FeRB and FeSAB recovered 8.3 mg-Se⋅g-composite−1 and 5.9 mg-Se⋅g-composite−1, respectively. Higher Se uptake was achieved at higher Fe-loads and lower acetone:biochar ratio, to a maximum of 17.3 mg-Se⋅g-composite−1 (FeRB). Washing after Fe-impregnation using deionized water diminished nitrate and Fe-leaching from the Fe-biochar composites while removing selenium. Se(VI) and sulfate uptake were observed when washed composites were tested in the presence of possible competing ions at environmentally relevant concentrations (Set=0 = 1.01 ± 0.03 mg⋅L−1; N–NO3-t=0 = 40.2 ± 0.2 mg⋅L−1; and SO42−t=0 = 496 ± 25 mg⋅L−1). One of the possible mechanisms of removal might be the complexation of Se with the iron oxyhydroxide deposits (goethite and hematite) found on the FeRB surface.
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•Iron oxide deposits were found on the surface of the Fe-biochar composites.•Modifying the biochar surface by steam activation results in less Fe-leaching.•Fe-biochar composites using non-activated biochar have higher Se uptake.•Leaching of N–NO3 and Fe can be eliminated by continuous washing the composites prior use.•Washed composites removed simultaneously Se and SO4 at environmental conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The chemical compositions of toolstones composed of clastic and chemical sedimentary rock are often not distinct among procurement locations. However, sedimentary toolstone sources may show ...variations in the structural characteristics of the included carbonaceous material (CM) related to differences in their postdepositional histories, providing a potential proxy by which procurement locations, rather than individual rock units, can be assessed as raw material sources for archaeological lithics. Here, we apply a well‐established method for investigating the nature of CM in sedimentary rocks, Raman spectroscopy of carbonaceous material (RSCM), to an archaeological case study. We test if the technique can be used to differentiate among toolstones from two procurement areas along the eastern slopes of the Canadian Rocky Mountains potentially used by pre‐European contact Indigenous inhabitants of the Hummingbird Creek Site (FaPx‐1). Artifacts found during excavations at Hummingbird Creek visually appear to match toolstone‐grade rocks in the site's vicinity. We analyzed source material from two localities: (1) the local toolstone around FaPx‐1 and (2) a toolstone procurement area ~45 km away associated with many precontact workshop sites. To test if the artifacts have compositions consistent with the local toolstones, we analyzed artifacts and potential source materials with RSCM as well as their major, minor, and trace element composition using X‐ray fluorescence (XRF). Our work is guided by the elimination of source locations using indirect geochemical proxies in accordance with the exclusionary Provenance Hypothesis. Both the structural and the chemical characteristics of the artifacts are similar to those of geologic samples from the nonlocal source location and are not consistent with samples collected locally, permitting the exclusion of local materials and suggesting that the inhabitants of FaPx‐1 used a variety of toolstones to manufacture the artifacts from materials that do not appear to be readily available near the site.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Erosional processes often rework materials of different ages into the same sedimentary facies, producing time-averaged deposits. Such reworking is common at archaeological sites, and researchers must ...consider the resulting time-averaging effects when using natural stratigraphy to situate artifacts and remains in time. At Scladina Cave, a Neandertal site in Belgium, we developed a method for identifying reworked facies and the stratigraphic provenance of mammal bones based on their post-mortem trace element characteristics and crystallinity. We collected sixty-two faunal remains from throughout the site's sedimentary sequence and analyzed them for trace element concentrations and crystallinity with laser ablation inductively coupled plasma mass spectrometry and Raman spectroscopy. Our novel approach, the ‘Perio-spot’ technique, quantifies the trace element characteristics and crystallinity from the most diagenetically altered part of a bone with high spatial resolution. Trace element concentrations, rare earth element patterns, and crystallinity of ‘Perio-spots' correlate throughout the Scladina sedimentary sequence. Based on stratigraphic trends in bone chemistry and crystallinity, we subdivide the Scladina sequence into two successive periods of early diagenesis, a period of later diagenesis, and a transitional period between the early and later diagenesis periods. The period boundaries also correspond to major climatic fluctuations identified in the site's stratigraphy by other means (e.g., palynology and heavy mineralogy). The stratigraphic provenance of nine cave bear femora support the confinement of reworking to within each of the diagenetic periods; the provenance of two indeterminate faunal remains that visually resemble the taphonomic alteration of the Scladina Neandertal (taphonomic proxies) suggest that the individual may be significantly older than previously hypothesized. Evaluating the temporal integrity of exhumed assemblages and the original sedimentary context of bones with our method is thus a valuable addition to archaeological analyses, especially beyond the temporal range of radiocarbon dating or in contexts with very low preservation potential of organic materials.
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•Taphonomic alteration of bone evaluated with the ‘Perio-spot’ technique.•Reworking and stratigraphic provenance identified by observing taphonomic alteration.•Taphonomic alteration of bone correlates with major climatic variations.•Reworking is confined to diagenetic periods we identified in sedimentary sequence.•Taphonomic proxies suggest the Scladina Child may be older than hypothesized.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Trace element concs., structure, and Pb isotope ratios investigated in BC obsidian.•Step-wise multiproxy provenancing procedure described and applied to case study.•14 artifacts analyzed with ...non-destructive and minimally-invasive techniques.•Pb isotope ratios of sources trend systematically north-south in the province.•Source affiliations showed a vector of ancient landscape use of over 600 km long.
Archaeology and geology inherently intersect when attempting to determine the geographic origin of lithic materials manufactured into artifacts by ancient people. Obsidian, or volcanic glass, is frequently found in archaeological sites, and researchers commonly use the trace element characteristics of obsidian artifacts to identify their source. However, the trace element concentrations of obsidian flows are not necessarily unique, potentially leading to inaccurate conclusions when used in isolation, especially if all possible sources have not been identified and systematically characterized. In this pilot study, we assess variations among the trace element, structural, and isotopic characteristics of obsidian sources in British Columbia and describe a multiproxy approach for provenancing obsidian artifacts. Our approach combines the survey of an artifact assemblage using non-destructive techniques with further analysis of a pre-selected subset of representative artifacts using minimally-invasive analytical methods. The initial non-destructive survey step includes determination of trace element concentrations by portable X-ray fluorescence and structural characteristics by Raman spectroscopy. The minimally-invasive step includes the measurement of lead isotope ratios and more precise trace element concentrations with split stream-laser ablation-inductively coupled plasma-mass spectrometry (SS-LA-ICP-MS) on only a select few representative artifacts. We tested this approach on 14 obsidian artifacts from an archaeological site in British Columbia. Our results provide multiple lines of evidence which indicate that two of the analysed artifacts likely originated from Mount Edziza, ~360 km north of the site, and all others likely originated from Anahim Peak, ~275 km south of the site. The combined use of multiple proxies significantly enhances confidence during sourcing studies and highlights the strength of multidisciplinary and multivariate geochemical approaches to archaeological challenges.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although conservation practices facilitate the preservation of museum collections, procedures used to stabilize ancient materials can alter their chemical and isotopic compositions, impacting the ...viability of such specimens for life history investigations. In this study, we applied two common consolidants – polyvinyl acetate (PVAc) and acrylic resin (Paraloid B-72™) – followed by two consolidant removal procedures to assess the impacts of these processes on the stable isotope compositions and structural characteristics of a series of subsamples taken from a representative archaeological faunal bone. We examined the collagen (δ13Ccol and δ15Ncol), structural carbonate (δ13Csc and δ18Osc), and phosphate (δ18Op) isotopic compositions of the bone sample before and after consolidation to evaluate consolidant removal procedures. We also measured δ13Csc, δ18Osc, and structural characteristics before and after the pre-treatment commonly used to remove organic matter and secondary carbonate prior to isotopic analyses.
Our results produced five main outcomes. First, an acetone treatment shorter than 48 h was sufficient to remove PVAc and acrylic resin from archaeological bone without altering the original δ13Ccol and δ15Ncol. Second, prolonged exposure (>48 h) to polar solvents during the consolidant removal procedure and collagen extraction modified collagen isotopic compositions, lowering its original δ13Ccol by 0.3–0.4 ‰ and increasing its original δ15Ncol by up to 0.9 ‰. Third, the consolidant application and removal procedures altered the original δ13Csc and δ18Osc. Fourth, the change in δ18Osc was likely caused by the bleach (2% NaClO at 20 °C for 72 h)/acetic acid (0.1 M for 4 h at 20 °C) pre-treatment applied prior to isotopic analyses. Fifth, our results confirm and expand on previous studies reporting that δ18Op remains unaltered after consolidant and solvent procedures. These outcomes provide a framework for obtaining reliable stable isotope compositions from archaeological bones that have been stabilized using consolidants.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
A biface workspace dating to ca. cal a.d. 100-400 was identified during recent excavation at the Sts'ailes-Coast Salish village of YāçkEtEl, on the Harrison River on the Northwest Coast of North ...America. Based on a range of analyses, we suggest that a specialist crafted large bifaces produced as prestigious objects for exchange within a ceremonial interaction sphere and smaller, more functional bifaces for household and local purposes. The workspace was a shed-like structure adjacent to their house, and the toolstone was acquired nearby from previously undocumented quarries within the territory. This is the only documented evidence for the manufacture of large prestigious bifaces in the region and consequently provides insights into the social relations of lithic acquisition, production, exchange, and consumption. In particular, we examine the social and economic roles and contributions of lithic specialists embedded within households.
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BFBNIB, NUK, PILJ, SAZU, UL, UM, UPUK
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