M D'Elia

Evaluation of Possible Contamination Sources in the 14C Analysis of Bone Samples by FTIR Spectroscopy

In the sample preparation laboratory of CEDAD (CEnter for DAting and Diagnostics) of the University of Lecce, a protocol for the quality control of bone samples based on infrared spectroscopy has been set up. The protocol has been recently developed as a check-in test with the aim to identify the presence of collagen in the samples, assess its preservation status, and determine whether the submitted bone samples are suitable for accelerator mass spectrometry (AMS) radiocarbon measurements or not. We discuss in this paper the use of infrared-based techniques to identify the presence of contaminants such as restoration and consolidation materials, humic acids, and soil carbonates, which, if not removed by the sample processing chemistry, can be sources of exogenous carbon and can thus influence the accuracy of the 14C determinations. Bone samples recovered in well-defined and previously dated archaeological contexts were intentionally contaminated, submitted to the standard method for collagen extraction and purification, and then characterized by means of Fourier transform infrared (FTIR) spectroscopy analyses performed in attenuated total reflection (ATR) mode before being combusted, converted to graphite, and measured by AMS. The study shows that the ATR-FTIR technique is an extremely powerful method for the identification of both the collagen and its contaminants and can supply important information during the selection and processing of samples to be submitted for 14C dating.

New bomb pulse radiocarbon records from annual tree rings in the northern hemisphere temperate region

The bomb radiocarbon spike induced by atmospheric nuclear detonations has been reconstructed at a latitude of 40N by measuring the 14C content in annual rings of a living pine (Pinus pinea) at the Accelerator Mass Spectrometry facility of the University of Lecce. We report how the samples were taken, selected, prepared for analysis, and measured. The results are in good agreement with other data sets available for the Northern Hemisphere temperate regions, showing that a curve for the calibration of 14C dates, valid for the whole Northern Hemisphere, can be established for the second half of the 20th century.

Radiocarbon Age Anomalies in Pre- and Post-Bomb Land Snails from the Coastal Mediterranean Basin

The shell carbonate of pre- and post-bomb samples of 2 species of terrestrial gastropods (Theba pisana and Cernuella virgata) sampled along the coast of Apulia, southern Italy, were dated using accelerator mass spectrometry and carbon stable isotopes were analyzed. The analyses show, for both species, significant anomalies in the radiocarbon age due to the possible presence of a 14C-depleted source of carbon in the formation of the shell aragonite. The magnitude of the age anomaly was quantified in the studied area to ~1000 14C yr.

Wiggle-Match Dating of Wooden Samples from Iron Age Sites in Northern Italy

Archaeological excavations carried out at the sites of Laion/Lajen (Bolzano/Bozen) and Stufles-Oberegger (Bressanone/Brixen) in northern Italy uncovered well-preserved wooden samples in cultural layers archaeologically dated to the Iron Age. From the 2 sites, different wooden samples were recovered that were well preserved enough to allow clear identification of the tree species and of the ring structure. Among the different wooden samples, 2 were selected for radiocarbon analyses: from Laion/Lajen, a beam with an unbroken sequence of 158 rings; from Stufles-Oberegger, a combusted trunk with a sequence of 217 rings. Both samples were identified as Larix decidua species. From each sequence, single rings were selected and submitted for accelerator mass spectrometry (AMS) 14C dating analysis at CEDAD. Conventional 14C ages were then calibrated to calendar ages using the IntCal04 atmospheric data set, while the statistical constraints resulting from the defined ring sequence were used to develop a wiggle-matching approach by making use of the Bayesian analysis functions available in OxCal. The obtained results are an important contribution in refining the chronology of the studied sites.

THE NEOLITHIC SITE OF SERRA CICORA: RESULTS OF THE AMS RADIOCARBON DATING

Bone and charcoal samples from the Neolithic site of Serra Cicora in the Salento Peninsula (southern Italy) have been dated by accelerator mass spectrometry (AMS). Measurements appear to support other archaeological evidence and have shown that 2 distinct phases of human occupation of the site can be identified: the first occupation in the Early Neo- lithic and a second occupation in the Middle-Late Neolithic. The results provide new information and are a fundamental con- tribution to the definition of the absolute chronology of the Middle-Late Neolithic in this part of Europe.

The oldest dated tree of Europe lives in the wild Pollino massif: Italus, a strip‐bark Heldreich's pine

How long do the oldest trees in Europe live? And where do they live? Recently, Konter et al. (2017) documented the discovery in Greece of Adonis, a Pinus heldreichii H.Christ with at least 1,075 tree rings, thus the oldest tree so far scientifically dated in Europe. An area of extreme interest to further explore these questions is the Pollino National Park (southern Italy, see Appendix S2), where maximum crossdated age of Heldreich’s pine had been previously reported as approaching a thousand years (Serre-Bachet 1985, Biondi 1992). After a 3-yr sampling campaign, we discovered a few millennium-old trees living on high-mountain cliffs (1,850– 2,150 m a.s.l.) in the Pollino Massif. The oldest sampled tree, which we called Italus (Fig. 1), became the subject of further investigation to determine its actual age. Italus has the typical shape of extremely old conifers, with dead spike top, strip-bark formation, and few live crown patches in the lower-middle part of the stem (Swetnam and Brown 1992). This Heldreich’s pine has diameter at breast height of 160 cm and is located on a steep rocky slope with cliff ledges. The stand is open, with little or no understory, generally undeveloped soils, and plenty of exposed dolomitic bedrock, hence the risk of wildfire spread is minimized. The Heldreich’s pine population occupies the vegetation zone just above beech forests that include old-growth stands with 500-yr old individuals, approaching the maximum longevity for this deciduous species (Di Filippo et al. 2015). Wood cores 5-mm in diameter were extracted using increment borers from the lower stem, which was hollow, and from exposed roots. Thanks to the particular configuration of the stem, straddling rocky and steep terrain that had eroded away, it was possible to collect increment cores from the root system close to the germination pith. To obtain a scientifically validated age for this old hollow tree, we developed a specific multistep dating procedure that combines tree-ring and radiocarbon analyses to match samples from a hollow stem and from exposed roots of a living tree. Increment cores extracted from the Italus stem revealed an innermost ring date of 955 CE, giving a total chronology length of 1,062 yr (955 CE–2,016 CE) (Fig. 2). Overall, ring-width patterns of Italus follow the typical features of isolated old trees, with relatively large increments in the first few cambial years, followed by a rapid decline towards a very long series of extremely small rings (Biondi and Qeadan 2008). Xylem increment is extremely low because of difficult environmental conditions, which typically lead to presence of extremely old individuals, as is the case with Pinus longaeva in Great Basin mountains of north America (Schulman 1954). A potential age estimate was then calculated using the increment core length and the stem diameter at the coring location. Given a 23.8 cm distance between the end of the core and the stem center (assuming a circular trunk), we used the average ring width for the innermost 20-50 rings (Di Filippo et al. 2017) to derive an estimate of 205–227 rings between the pith and the first dated ring. With this estimate, the pith date could fall in the 727–749 CE time interval. The total estimated stem age, obtained by adding the number of crossdated tree rings with the estimated missing ones, could therefore be 1,267–1,289 yr. Improving the age determination for Italus required analyzing the increment cores collected from the exposed roots. Anatomical features of root samples, such as the clear presence of latewood, indicated that those roots had been exposed for quite some time. Exposed roots often contain ring patterns that are not synchronous with rings in buried roots, and in our case there was also no clear correlation with the stem ring-width patterns. An abrupt growth decline was evident in the stem ring widths (Fig. 2) between 1,016

Chronostratigraphic Sequence of Santuario della Madonna Cave (Calabria, Southern Italy): AMS Radiocarbon Data from a New Excavation Area

The Santuario della Madonna Cave, located near Praia a Mare (Cosenza), along the northwestern coast of Calabria (southern Italy), has an impressive stratigraphy, with occupation phases spanning from the late Paleolithic to the advanced phases of the Middle Bronze Age. Recently, a new excavation area has been opened in the cave from which short-lived vegetal remains were sampled and submitted for accelerator mass spectrometry (AMS) radiocarbon dating. The aim of this study was to define an accurate chronology of the different cultural aspects and to explore the potentialities resulting from application of advanced statistical tools for 14C data analysis in such a context.