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Radiocarbon (¹⁴C) provides a way to date material that contains carbon with an age up to ~50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric ¹⁴C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report ¹⁴C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the ¹⁴C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.

Radiocarbon dating Pacific archaeological sites is fraught with difficulties. Often situated in coastal beach ridges or sand dunes, these sites exhibit horizontal and vertical disturbances, datable materials such as wood charcoal are typically highly degraded, may be derived from old trees or driftwood unless specifically identified to short-lived material, while bone collagen rarely survives in tropical conditions. Shell, therefore, is the most logical material for dating Pacific sites since it is resistant to alteration, can be sampled to ensure only the last few seasons of growth are represented and is often closely tied to human economic activities. However, shell radiocarbon (14C) dating has been plagued by interpretive problems largely due to our limited knowledge of the 14C cycle in nearshore marine and estuarine environments. Consequently, shell dates are typically ignored in regional chronometric evaluations and in recent years shell is often avoided for dating altogether. Recent advances in our understanding of the source of shell 14C as well as the development of the first South Pacific Gyre model of changing marine 14C over time, combined with Bayesian statistical modelling, now provide us with insight into the value of these shell radiocarbon dates. Here we present a revision of the age of the To'aga site on Ofu Island-an early occupation site associated with the initial Polynesian Plainware period in Sāmoa, the earliest use of which we date to between 2785 and 2607 cal BP (68% probability).

We present successful ⁸¹Kr-Kr radiometric dating of ancient polar ice. Krypton was extracted from the air bubbles in four ∼350-kg polar ice samples from Taylor Glacier in the McMurdo Dry Valleys, Antarctica, and dated using Atom Trap Trace Analysis (ATTA). The ⁸¹Kr radiometric ages agree with independent age estimates obtained from stratigraphic dating techniques with a mean absolute age offset of 6 ± 2.5 ka. Our experimental methods and sampling strategy are validated by (i) ⁸⁵Kr and ³⁹Ar analyses that show the samples to be free of modern air contamination and (ii) air content measurements that show the ice did not experience gas loss. We estimate the error in the ⁸¹Kr ages due to past geomagnetic variability to be below 3 ka. We show that ice from the previous interglacial period (Marine Isotope Stage 5e, 130–115 ka before present) can be found in abundance near the surface of Taylor Glacier. Our study paves the way for reliable radiometric dating of ancient ice in blue ice areas and margin sites where large samples are available, greatly enhancing their scientific value as archives of old ice and meteorites. At present, ATTA ⁸¹Kr analysis requires a 40–80-kg ice sample; as sample requirements continue to decrease, ⁸¹Kr dating of ice cores is a future possibility.

Pottery is one of the most commonly recovered artefacts from archaeological sites. Despite more than a century of relative dating based on typology and seriation , accurate dating of pottery using the radiocarbon dating method has proven extremely challenging owing to the limited survival of organic temper and unreliability of visible residues . Here we report a method to directly date archaeological pottery based on accelerator mass spectrometry analysis of C in absorbed food residues using palmitic (C ) and stearic (C ) fatty acids purified by preparative gas chromatography . We present accurate compound-specific radiocarbon determinations of lipids extracted from pottery vessels, which were rigorously evaluated by comparison with dendrochronological dates and inclusion in site and regional chronologies that contained previously determined radiocarbon dates on other materials . Notably, the compound-specific dates from each of the C and C fatty acids in pottery vessels provide an internal quality control of the results and are entirely compatible with dates for other commonly dated materials. Accurate radiocarbon dating of pottery vessels can reveal: (1) the period of use of pottery; (2) the antiquity of organic residues, including when specific foodstuffs were exploited; (3) the chronology of sites in the absence of traditionally datable materials; and (4) direct verification of pottery typochronologies. Here we used the method to date the exploitation of dairy and carcass products in Neolithic vessels from Britain, Anatolia, central and western Europe, and Saharan Africa.

The huge volcanic eruption at Thera (Santorini), situated in the Aegean Sea, occurred within the Late Minoan IA archaeological period. However, its temporal association with Egyptian history has long been a controversial subject. Traditionally, the eruption was placed in the early 18 th Dynasty, associated with Pharaoh Thutmose III as the youngest option or with Pharaoh Nebpehtire Ahmose as the oldest possibility. We investigated museum objects from the 17 th and early 18 th Dynasty, at the transition from the Second Intermediate Period to the New Kingdom, a period hardly studied with radiocarbon dating. Our research facilitated the first-ever direct radiocarbon time comparison between this Dynastic transition period and the Minoan Thera eruption. Detailed results are presented of a mudbrick from the Ahmose Temple at Abydos (British Museum), a linen burial cloth associated with Satdjehuty (British Museum), and wooden stick shabtis from Thebes (Petrie Museum), evaluated within a comprehensive context of historical Egyptian chronology options. Since the above items cannot be arranged in a stratigraphic sequence, Bayesian analysis could not be used. We adopted an alternative strategy within radiocarbon time space. Comparing our uncalibrated dates of 17 th and early 18 th Dynasty objects with a robust series of uncalibrated radiocarbon dates for the Minoan Thera eruption, it becomes clear that the two data sets have a different time signature. The Minoan eruption is older than the reign of Nebpehtire Ahmose, the first king of the 18 th Dynasty, who reunited Upper and Lower Egypt. Our calibrated results support a low chronology for his reign and the beginning of the New Kingdom. Previous radiocarbon dates of king Senusert III support a high chronology for the Middle Kingdom. Therefore, the Second Intermediate Period, sandwiched in between these united Egyptian Kingdoms, embodies a significant time interval, as also indicated by Bennett’s genealogical studies of the El-Kab governors.

The Laboratoire de Mesure du Carbone 14 (LMC14) has operated a radiocarbon dating laboratory for almost twenty years with ARTEMIS, the Accelerator Mass Spectrometer (AMS) based on a NEC 9SDH-2 Pelletron tandem accelerator. A first status report describing the chemical pretreatment methods was published in 2017 (Dumoulin et al. 2017). This article summarizes updates of the routine procedures and presents new protocols. The quality checks in place at the LMC14 and results obtained for the GIRI international inter-comparison are reported. New protocols developed by the laboratory over the last five years are described with the preparation of iron, lead white, cellulose, calcium oxalate, and mortar. This report also provides a summary of practical information for sample preparation and can help the laboratory users who provide samples and publish results to better understand all the work behind a 14C dating.

The Belfast Ramped Pyroxidation/Combustion (RPO/RC) facility was established at the 14CHRONO Centre (Queen’s University Belfast). The facility was created to provide targeted analysis of bulk material for refined chronological analysis and carbon source attribution for a range of sample types. Here we report initial RPO results, principally on background material, but also including secondary standards that are routinely analyzed at 14CHRONO. A description of our setup, methodology, and background (blank) correction method for the system are provided. The backgrounds (anthracite, spar calcite, Pargas marble) reported by the system are in excess of 35,000 14C years BP with a mean age of 39,345 14C years BP (1σ = 36,497–43,800 years BP, N=44) with F14C = 0.0075 ± 0.0032. Initial results for standards are also in good agreement with consensus values: TIRI-B pine radiocarbon age = 4482 ± 47 years BP (N=13, consensus = 4508 years BP); IAEA-C6 ANU Sucrose F14C= 1.5036 ± 0.0034 (N=10, consensus F14C = 1.503). These initial tests have allowed problematic issues to be identified and improvements made for future analyses.

Radiocarbon (14C) measurements of foraminifera often provide the only absolute age constraints in marine sediments. However, they are often challenging as their reliability and accuracy can be compromised by reduced availability of adequate sample material. New analytical advances using the MIni CArbon DAting System (MICADAS) allow 14C dating of very small samples, circumventing size limitations inherent to conventional 14C measurements with accelerator mass spectrometry (AMS). Here we use foraminiferal samples and carbonate standard material to assess the reproducibility and precision of MICADAS 14C analyses, quantify contamination biases, and determine foraminiferal 14C blank levels. The reproducibility of conventional 14C ages for our planktic (benthic) foraminiferal samples from gas measurements is 200 (130) yr, and has good precision as illustrated by the agreement between both standards and their reference values as well as between small gas- and larger graphitized foraminiferal samples (within 100±60 yr). We observe a constant contamination bias and slightly higher 14C blanks for foraminifera than for carbonate reference materials, limiting gas (graphite) 14C age determinations for foraminifera from our study sites to ~38 (~42) kyr. Our findings underline the significance of MICADAS gas analyses for 14C on smaller-than-conventional sized foraminiferal samples for paleoclimate reconstructions and dating.