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Abstract We conducted inter-laboratory AMS 14C dating of bones of the Miesenheim IV elk (Rhineland, Germany), buried under Laacher See tephra dated to ca. 11,060 BP (13,000 cal BP). The weighted mean of the new dates, which range from 10,920 to 11,270 BP, is 11,092 ± 19 BP. The consistent results from five AMS laboratories are important in two respects. First, they demonstrate that collagen processed by traditional methods can yield accurate ages; the newly obtained 14C dates are in accord with previous hydroxyproline 14C value generated at the Oxford AMS laboratory within the first round of inter-comparison (Fiedel et al., 2013). The results of the first inter-comparison are clearly flawed, except for hydroxyproline 14C date (see Fiedel et al., 2013), and must be affected by the waxy/dark, presumably humic/organic-based contaminant. Second, they provide a new suite of radiocarbon dates for the Laacher See volcanic eruption, a crucial anchor point for Late Glacial chronology in central Europe. [ABSTRACT FROM AUTHOR]

Abstract: This research investigates plaster and mortar samples from different structures at Petra, Southern Jordan. It aims at radiocarbon dating organic inclusions uncovered from these samples in order to refine the chronology of the structures sampled. One of the structures has a Latin inscription so it was used to crossdate its radiocarbon date. The radiocarbon dates of most of the samples synchronize the archaeological records and dates of the structures. [ABSTRACT FROM AUTHOR]

Abstract: We summarize how radiocarbon measurements are made using accelerator mass spectrometry. We also discuss some complications inherent in the radiocarbon-dating method when calibrating radiocarbon dates to calendar dates. For example, measurements of radiocarbon (14C) in some types of materials are complicated by a “reservoir effect”, caused by an apparent age of the source reservoir that differs from the contemporary atmospheric surface 14C value. In other cases, mobile carbon sources in nature can produce mixed sources of carbon. We explore these effects and discuss their possible implications for 14C measurements and how we can deal with them. [Copyright &y& Elsevier]

Two Donax obesulus and two Protothaca asperrima shells collected prior to the nuclear testing of the 1950's were micromilled at sub-seasonal resolution to yield new reservoir effect (ΔR) estimates for the coast of Peru. Shells from northern (4°40′S to 8°14′S) and central (13°52′S) Peru produced ΔR values of 123 ± 50 and 110 ± 49 years respectively. We found such values statistically indistinguishable from each other while reporting intra-annual ΔR variability along shells ontogeny in agreement with previously published regional ΔR values. This similarity suggests radiocarbon dating of short-lived (<1.5 years) mollusks shells is a useful tool for comparing marine radiocarbon signals. Additionally, our analysis of ΔR and δ18O changes along shells' ontogeny found a tenuous relationship between them. We are not the first one to report these phenomena in Peruvian upwelling, but we are the first to suggest that fast Lagrangian water mixing as a mechanism behind it. [ABSTRACT FROM AUTHOR]