The automatic graphitization system (AGE3) by IonPlus is very popular among radiocarbon dating laboratories. Usually, solid samples are burnt in an elemental analyzer (EA), and the gaseous CO2 is transferred for graphitization. Our system is coupled also with an isotope ratio mass spectrometer (IRMS), which measures the δ13C and δ15N of that gas. Some less routine pretreatment protocols require the production of gaseous samples and prevent the possibility of using the EA-AGE3 system, as the EA is used for solid samples only. In order to use that system, including the measurements of stable isotopes, we developed a glass tube cracker that connects to the EA. The device is routinely used in our laboratory and is mainly built from Swaglok catalog parts. We show that the background (blank) levels of a marble standard are indistinguishable between using the cracker and burning solid marble using the EA. We further demonstrate that the δ13C values are consistent and that the extraction efficiency when using the device is above 93%. Full descriptions, drawings, and working protocol are supplied.

The Minoan eruption of Santorini, Greece, is an important and often-debated chronological marker in contexts of the Eastern Mediterranean region. Among various age estimates of this event, one based on wiggle-matching of radiocarbon (14C) dates from an olive branch found in Santorini by Friedrich et al. (2006) has been widely discussed. Calibrated age estimates based on wiggle-matching of these 14C ages have been changing with improvements in the 14C calibration curve. As also shown earlier, calibration of average 14C age of multiple tree rings dated together should not be done using a single-year calibration curve. Since recent calibration curves include many single-year 14C datasets, a different approach should be considered to calibrate the average 14C age of block of multiple tree rings. Here we have demonstrated the use of multiple moving average (MA) calibration curves for calibrating the sequence of four 14C ages reported for the Santorini olive branch. The resultant calibrated ages for the Minoan Eruption are relatively younger than previous estimates and range from the late-17th century BCE to mid-16th century BCE date.

Vast burial fields, some with hundreds of burials, categorize the southern Levant’s Intermediate Bronze Age period (IBA). This phenomenon contrasts with a limited number of burials found from the preceding Early Bronze III period. This paper presents the first radiocarbon dating research of sampled bones from shaft tombs from five IBA burial sites across Israel: Yehud, Jebel Qaaqir, Sheikh-Danon, Hazorea, and Kefar-Veradim. Prescreening methods, including Fourier transform infrared analysis, were applied to identify best-preserved collagen in archaeological bones for radiocarbon dating. Overall, the measured date ranges cover the IBA timeline, supporting the observation that the IBA signature shaft tombs are a fundamental tradition of the IBA culture, at least in Israel. A single IBA shaft tomb at Jebel Qaaqir which contained remains of multiple humans, supplied different dates for various people, spanning over a few hundred years. These results suggest a tribal or family-oriented IBA community with a long-lasting tradition reflected in centuries of collective burial practices.

The following paper presents the results of radiocarbon (14C) dating of Middle Bronze Age (MB) contexts in Jerusalem. The dates, sampled with microarchaeology methods from three different locations along the eastern slopes of the city’s ancient core, reveal that Jerusalem was initially settled in the early phases of the period, with public architecture first appearing in the beginning of the 19th century BC and continued to develop until the 17th century BC. At that time, a curious gap in settlement is noted until the 16th century BC, when the site is resettled. The construction of this phase continued into the early 15th century BC. The dates presented are discussed in both the site-level, as well as their far-reaching implications regarding MB regional chronology. It is suggested here that the high chronology, dating the Middle Bronze Age between 2000 and 1600 BC is difficult to reconcile with dates from many sites. In contrast, a more localized chronology should be adopted, with the Middle Bronze Age continuing into the early 15th century BC in certain parts of the southern Levant, such as the region of Jerusalem.

Radiocarbon (14C) dating of anthropogenic carbonates (CaCO3) such as ash, lime plaster and lime mortar, has proven a difficult task due to the occurrence of a number of contaminants embedded within the CaCO3 pyrogenic binder. These include 14C-free geologic components and/or secondary phases bearing an unknown amount of 14C, and thus the alteration of the original pyrogenic isotopic signature of the material results in major age offsets when carbon recovery is performed through acid hydrolysis. Here we present a characterization/quantification approach to anthropogenic carbonates that includes Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thin section petrography, thermogravimetric analysis and scanning electron microscopy coupled with high-resolution cathodoluminescence, with which we identified the pyrogenic CaCO3 fraction in an aerial lime plaster and two hydraulic mortars. The preserved pyrogenic component was then isolated by density separation and its purity checked again using FTIR. Carbon was recovered through thermal decomposition in vacuum. The resulting 14C age matches the expected age of the lime plaster, whereas hydraulic mortars are slightly offset due to the carbonation of calcium hydroxide lumps. This approach highlights the importance of a dedicated characterization strategy prior to dating and may be applied to aerial lime plasters to obtain accurate ages.

Insoluble bone collagen is one of the most common materials used for high-resolution radiocarbon (14C) dating. Unfortunately, in some bones, poor preservation of the insoluble collagen excludes the possibility of dating. During the burial of the bone the collagen sometimes degrades into peptides. These peptides are soluble in the acid used to dissolve the bone mineral. It is known that under appropriate conditions, collagen has the ability to self-assemble. Here we exploit this capability and present a method for reassembling the soluble collagen peptides in archaeological bones and dating them. We treated the acid fraction generated during the demineralization of the bone by desalting and neutralizing the solution by dialysis. During the dialysis, the soluble collagen peptides reassemble and precipitate in the dialysis bag. We used FTIR spectroscopy to determine that the precipitated material is indeed collagen. The 14C dates obtained from the reassembled collagen were compared to the dates of “standard” insoluble collagen, extracted in parallel from the same bone. Although there are some divergences of the dates, 3 out of 10 samples could have been dated only by the reassembled collagen. This shows that collagen peptides reassembly can be a valuable tool for dating bones with little or no insoluble collagen.

Obtaining accurate age determinations from minerals in archaeological ash is a major unsolved issue in radiocarbon (14C) dating. This is because the original 14C content of calcite, the main component of ash, is altered by isotopic exchange. Pyrogenic aragonite, another mineral phase recently discovered in ash, might preserve its 14C signature through time. Using a new method based on density separation and step combustion, we were able to isolate and date aragonitic ash from an archaeological destruction horizon of known age. Here we show that the 14C age of aragonite matches the age of the destruction horizon. Our results demonstrate that pyrogenic aragonite is a short-lived material suitable for 14C dating and directly related to human activities involving the use of fire, thus bearing major implications for the establishment of absolute chronologies for the past 50,000 yr.

The Dangoor REsearch Accelerator Mass Spectrometer (D-REAMS) is a dedicated carbon-only AMS system, built by National Electrostatics Corporation (NEC). It is based on the 1.5SDH Pelletron, operating at 460 keV. The machine was installed at the Weizmann Institute of Science, Rehovot, Israel, in January–February 2013, and passed the acceptance test on March 2013. Since then, over 4500 samples have been successfully measured. Here, we present the results of an intercomparison experiment, done in collaboration with the Vienna Environmental Research Accelerator (VERA), and some typical operation parameters and measurement values of the new AMS system.

The absolute chronology of the Kura-Araxes (KA) culture in the Southern Caucasus still represents a challenge due to the fragmentation and inadequacy of the radiocarbon record, as well as the inconsistencies in material typologies in the region. Recent archaeological fieldwork at the site of Aradetis Orgora in the Shida Kartli region of Georgia revealed four occupation levels dating to the KA II phase according to the local relative chronology. 14C samples were collected from reliable contexts and further selected according to reliability criteria, taking into account both archaeological issues and lab procedures. FTIR was applied in order to determine the preservation of charcoals and to monitor the efficiency of lab treatments on all the samples. Only accurate 14C measurements were selected for Bayesian analysis incorporating stratigraphic information. Two models were run, the second of which simulated intervals corresponding to unexcavated stratigraphy or due to a lack of samples. In this article, the available 14C dates for the KA occupation at Aradetis are presented for the first time and analyzed using Bayesian principles. The results of Bayesian modeling suggest that the occupation of the excavated KA II levels cover the period between 3040–2810 BC (simple model) or 3090–2720 BC (interval model).

The Pre-Pottery Neolithic B (PPNB) site of Yiftahel, Israel, contains abundant plaster floors. We surveyed the states of preservation of the plasters using an infrared spectroscopic assay that characterizes the extent of disorder of the atoms in the calcite crystal lattice. We identified the 3 best-preserved plaster samples that had disorder signatures most similar to modern plaster. We then studied the surface layers, fine-grained matrices, and large aggregates of these samples using micromorphology, Fourier transform infrared (FTIR) microscopy, stable carbon and radiocarbon concentrations. Even though some of the plaster components have a geogenic appearance in micromorphology slides and in FTIR spectra, the 14C analyses show that all components were exposed to high temperatures and as a result were equilibrated with the 14C content of the atmosphere ∼10,000 yr ago. This implies that the plasters at Yiftahel were produced entirely from heat-altered calcite. We also show that these plasters have undergone significant diagenesis. The plaster component with the most disordered atomic signature, and hence the most similar in this respect to modern plaster, did indeed produce a 14C date close to the expected age.

This study focuses on radiocarbon dating of mortars that have withstood city fires and display visible fire damage effects. Some fire-damaged and undamaged original Medieval mortars from the same site have also been tested. The mortars were heated at different temperatures and then analyzed using the same preparation procedures as in 14C dating of mortars to see what kind of changes the heating would introduce to the mineralogy, chemistry, and the carbon and oxygen isotope ratios. We found that decarbonation during heating starts at ∼600 ° and recarbonation starts as soon as the temperature drops. Already after a few days, most of the lost CO2 has been replaced with atmospheric CO2. The renewed carbonates are readily soluble in the acid hydrolysis process and their carbon and oxygen isotopes have a light signature. Fire-damaged historical mortars display the same features. If a long time has elapsed between hardening of the original mortar and the fire, the new carbonates have 14C concentrations that point to the fire event rather than to the building event. In several cases, the fire-damaged mortars have an easily soluble carbonate fraction with a 14C age that could be related to a major fire event, but still most of the soluble carbonate yields a 14C age that seems like a reasonable age for the original construction.

Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.