Radiocarbon measurements of iron girders from Aachen cathedral

This study was motivated by a desire to improve understanding of the sources contributing to the carbon that is an important component of airborne particulate matter (PM). The ultimate goal of this project was to lay a ground work for future tools that might be easily implemented with archived or routinely collected samples. A key feature of this study was application of radiocarbon measurement that can be interpreted to indicate the relative contributions from fossil and non-fossil carbon sources of atmospheric PM. Size-resolved PM and time-resolved PM{sub 10} collected from a site in Sacramento, CA in November 2007 (Phase I) and March 2008 (Phase II) were analyzed for radiocarbon and source markers such as levoglucosan, cholesterol, and elemental carbon. Radiocarbon data indicates that the contributions of non-fossil carbon sources were much greater than that from fossil carbon sources in all samples. Radiocarbon and source marker measurements confirm that a greater contribution of non-fossil carbon sources in Phase I samples was highly likely due to residential wood combustion. The present study proves that measurement of radiocarbon and source markers can be readily applied to archived or routinely collected samples for better characterization of PM sources. More accurate source apportionment will support ARB in developing more efficient control strategies.

Bayesiansk kronologisk modellering som redskab i den lovpligtige arkæologi

Much attention has focused recently on the lateglacial period in north-west Europe, especially on the problems of climatic subdivision and chronostratigraphic definition1–3. Correlation and classification of lateglacial stratigraphy relies heavily on radiocarbon dating, but because the lateglacial represents a relatively short interval of geological time (14,000–10,000 yr BP) with comparatively slow rates of sedimentation, the stratigraphic resolution achieved in radiocarbon dating may be questioned—a 5-cm thick sample may represent an age span significantly greater than the analytical uncertainty (± 1σ) associated with the radiocarbon measurement. Results are presented here for a radiocarbon-dated pollen stratigraphy based on sediments from Llyn Gwernan, a small freshwater lake situated on the northern flank of Calder Idris, 3km south-west of Dolgellau, North Wales (grid ref. SH 703 159) where a remarkable thickness of lateglacial organic deposits preserves a detailed biostratigraphic record and permits a greater resolution of the lateglacial 14C time scale than is usual. The data are summarized in Fig. 1 and comparisons are made within the framework of previously published dates for Wales in Fig. 2.

Late Middle Paleolithic of Southern Poland: Radiocarbon dates from Ciemna and Obłazowa Caves

Integration of direct radiocarbon dating, genetic studies and taxonomy of small mammals to investigate the chronology of past climatic oscillations: The Last Glacial Maximum sequence of Grotta della Ferrovia (Fabriano, Italy)

Bone is one of the main sample types used for building chronologies in archaeology. It is also used in other research areas such as palaeodiet and palaeoenvironmental studies. However, for results to be accurate, samples must be free of exogenous carbon. Contamination can originate from a wide range of sources in the post-depositional environment but may also occur during excavation and post excavation activities (i.e. with the application of conservation materials) or during laboratory handling. Efficient procedures to remove contamination are therefore crucial prior to radiocarbon or stable isotope measurements. This work describes the development of an innovative sample pretreatment for bones, based on using supercritical CO2, which shows unique solvation properties. The effectiveness of supercritical fluid extraction (SFE) to remove conservation materials was compared with that obtained when applying a routine extraction based on the use of organic solvents (methanol, acetone and chloroform). The chemical composition of the bone samples before and after the two pre-treatments was then investigated using analytical pyrolysis-based techniques: EGA-MS (Evolved Gas Analysis-Mass Spectrometry) and Py-GC/MS (Pyrolysis-Gas Chromatography coupled with Mass Spectrometry). Collagen samples extracted from the same bones, prepared with the two cleaning protocols, were also radiocarbon dated by Accelerator Mass Spectrometry (AMS). The results of this study show that SFE is an efficient alternative method because it was as effective as the established treatment protocol. It removes contaminants such as conservation materials from bone samples with a minimum of handling and can be used routinely in radiocarbon dating laboratories. This work also demonstrates that analytical pyrolysis is not only a very efficient method to identify contaminants in bones but also to assess the effectiveness of the pretreatment prior to the radiocarbon measurement of the samples.

Iron Girders and Beams

Iron Girders and Beams

Radiocarbon dating, reservoir effects, and calibration

Current protocols for ancient DNA and radiocarbon analysis of ancient bones and teeth call for multiple destructive samplings of a given specimen, thereby increasing the extent of undesirable damage to precious archaeological material. Here we present a method that makes it possible to obtain both ancient DNA sequences and radiocarbon dates from the same sample material. This is achieved by releasing DNA from the bone matrix through incubation with either EDTA or phosphate buffer prior to complete demineralization and collagen extraction utilizing the acid-base-acid-gelatinization and ultrafiltration procedure established in most radiocarbon dating laboratories. Using a set of 12 bones of different ages and preservation conditions we demonstrate that on average 89% of the DNA can be released from sample powder with minimal, or 38% without any, detectable collagen loss. We also detect no skews in radiocarbon dates compared to untreated samples. Given the different material demands for radiocarbon dating (500 mg of bone/dentine) and DNA analysis (10–100 mg), combined DNA and collagen extraction not only streamlines the sampling process but also drastically increases the amount of DNA that can be recovered from limited sample material.

This dataset is the outcome of an INSTAP-funded project “An Aegean Prehistory Written in Radiocarbon Dates”. It includes 3159 14C dates from 353 sites in Greece and reflects an attempt to exhaustively collect and cross-check all published radiocarbon dates from existing databases, original publications and preliminary reports using both international and Greek sources (376 sources in total). Although originally targeting prehistoric dates, all dates coming from archaeological or environmental sampling were integrated in the final dataset regardless of chronological period. Sites have been identified and positioned as accurately as possible, while additional information on sampling procedures, sample material and stratigraphic context have been recorded. Funding statement: The Institute for Aegean Prehistory (INSTAP) provided the core funding for the “An Aegean Prehistory Written in Radiocarbon Dates” project which ran between 2016–2017. Previous support by INSTAP to Yannis Maniatis for the radiocarbon dating of Early Neolithic settlements in Greece in NCSR Demokritos Radiocarbon Laboratory allowed for several dates to be processed and included in the present work. Work related to data cleaning and terminology mapping was implemented as part of the dataset preparation process to be ingested in the ARIADNEplus portal. ARIADNEplus (Advanced Research Infrastructure for Archaeological Database Networking in Europe) is a project funded by the European Commission under the H2020 Programme, contract no. H2020-INFRAIA-2018-1-823914. The views and opinions expressed in this publication are the sole responsibility of the authors and do not necessarily reflect the views of the European Commission.

ABSTRACTExcavations in 1970, 1996, and 1999 at Site QJ-280, Quebrada Jaguay, in southern Peru, yielded enough dateable terrestrial plant material to establish an extensive radiocarbon chronology for the site. QJ-280 is one of oldest well-dated fishing sites in the Americas: it was occupied from the terminal Pleistocene to the mid-Holocene (about 13,000–8,300 calibrated years BP) based on 42 terrestrial radiocarbon dates, encompassing the Jaguay and Machas Phases of the local archaeological sequence. In addition to the terrestrial dates, radiocarbon measurements on valves of two marine surf clam (Mesodesma donacium) individuals from a single, well-dated mid-Holocene Manos Phase archaeological context have provided insight into marine upwelling conditions during the occupation of Quebrada Jaguay. The marine reservoir age varied between 130 and 730 14C years during the brief lives of the two clams (up to 5 years each), and varied by up to 530 14C years within an individual valve, suggesting strong and variable deep marine upwelling; conditions broadly similar to those that exist in coastal Peru today. These rapid variations in marine radiocarbon age suggest that marine radiocarbon dates from environments with variable upwelling could be skewed by up to hundreds of years.

Radiocarbon dating is a widely used method in archaeology and earth sciences, but the precision of calibrated dates from single radiocarbon measurements can be difficult to understand. This study investigates the precision of calibrated radiocarbon dates depending on the uncertainties of the measurement and the details of the calibration curve. Using data for the Holocene epoch and the IntCal20 calibration curve, over 1,000,000 hypothetical radiocarbon measurements were calibrated and analyzed. The study shows that high-precision measurements can yield calibrated date ranges from less than 50 years to more than 200 years (at the 95.4% probability) depending on the specifics of the calibration curve. This research may serve as a tool for planning future studies and assessing whether high-precision measurements are beneficial for proposed case.

ABSTRACTThe chronometric dating of ceramic objects is normally achieved by thermoluminscence techniques (TL). Here we report both TL and a radiocarbon measurements on a Chinese earthenware hu jar (Harvard University Art Museums LTL1.2001.23 a,b). TL dates were obtained from earthenware core samples using established methods. The radiocarbon date was obtained from an organic coating present on the jar surface. The coating was preliminarily identified as urushi by a comparison of its FTIR absorption spectrum to absorption spectra obtained from modern and ancient lacquer standards. The material was found to be insoluble in a variety of solvents, mineral acids, and bases. Combustion and elemental analysis revealed that 64% of the coating mass was carbon. C measurement by AMS was carried out on a 3.9 mg sample of chemically cleaned lacquer. This measurement generated a date of 2191 ± 38 BP. Calibration of this measurement placed the age of the jar between 390BC and 160 BC at the 95% confidence interval. The calibrated radiocarbon date corroborated the TL measurement placing the jar at between 2400 and 1500 years old (400 BC to 500 AD). These findings also agreed with stylistic evidence that the jar was produced during the Western Han period (206 BC-AD 9). The literature on urushi composition, its pigment compatibility, its high carbon content, its apparent chemical stability, and the small sample required for C-accelerator mass spectrometry suggests that other lacquer-coated objects might be dated using a similar approach.

The implication of varying 14C concentrations in carbon samples extracted from Mongolian iron objects of the Mongol period