Study of Bone Radiocarbon Dating Accuracy at the University of Arizona NSF Accelerator Facility for Radioisotope Analysis (original) (raw)
Related papers
2012
Bone chemical treatment for radiocarbon dating has drawn the attention of different laboratories since dates of bones and charcoals found in the same layer often disagree. Excluding diet-related reservoir effects, this observation is likely due to a nonoptimized procedure of contaminant removal from the extracted collagen. In this study, systematic work on the bone chemical treatment was performed with the aim to investigate the effect of each known procedure (i.e. AAA, GEL, and ULTR) on the collagen used for 14 C dating. The isolation and purification of lipids from animal tissues was performed to estimate eventual offsets induced by the applied methods, by comparing the 14 C ages of lipids with those of collagen. Moreover, cremated bones were treated for the first time at CIRCE. Measured 14 C isotopic ratios on these samples were used to evaluate the accuracy of the applied procedure by comparing against the results for charcoals found in the same archaeological context as the bones.
AMS Radiocarbon Dating of Bones at LSCE
Radiocarbon, 2003
In this paper, we explain our routine pretreatment of bone for radiocarbon dating by accelerator mass spectrometry (AMS), based on the specific reaction between amino acids and ninhydrin described by Nelson (1991). The values and uncertainties of the total system background are presented as a function of the carbon sample mass and the reliability of this method is discussed.
Studies Towards a Method for Radiocalcium Dating of Bones
Radiocarbon, 1989
We made preliminary AMS measurements of 41Ca/Ca ratios in bone and limestone specimens with the Argonne Tandem-Linac Accelerator System (ATLAS). We were able to avoid pre-enrichment of 41Ca used in previous experiments due to a substantial increase in Ca-beam intensity. Most of the measured ratios lie in the 10-14 range, with a few values below 10-14. In general, these values are higher than the ones observed by the AMS group at the University of Pennsylvania. We discuss possible implications of these results. We also present the current status of half-life measurements of 41Ca and discuss 41Ca production processes on earth.
CAN WE USE CALCINED BONES FOR 14C DATING THE PALEOLITHIC?
Radiocarbon, 2013
This work aims to test the reliability of calcined bones for radiocarbon dating of the Paleolithic. Fifty-five calcined bone samples coming from Aurignacian and Gravettian layers at Abri Pataud (Dordogne, France) were selected based on their macroscopic features. For each sample, the heating state was estimated on the basis of bone crystallinity (splitting factor [SF] using FTIR) and 13 C value. Twenty-seven bone samples (3 unburnt and 24 calcined) from 5 different levels were prepared for 14 C dating. The majority (15/24) of the calcined samples had to undergo a sulfix treatment prior to graphitization, probably due to the presence of cyanamide ion in these samples. The comparison between our results and recently published dates on bone collagen for the same levels shows that unburned bone apatite is systematically too young, while a third of the calcined bones fall within or very near the range of expected age. No clear correlation was found between 14 C age offset and 13 C value or SF. Most of the sulfixed samples (14/16) yielded ages that were too young, while almost all of the non-sulfixed samples (8/9) gave ages similar or <0.2 pMC from the expected minimum age. Although preliminary, these results suggest that sulfix should be avoided if possible and that clean CO 2 gas from well-calcined Paleolithic bones can provide reliable 14 C ages.
Accelerator radiocarbon dating at the molecular level
Journal of Archaeological Science, 1991
Molecular leveP4C dating is the isolation of specific classes of molecules for their _4C dating by accelerator mass spectrometry (AMS). Complex matrices such as fossil bone are difficult to date due to their extreme chemical heterogeneity. By isolating individual amino acids, contaminants (humates) are removed and crystalline amino acids result.
Radiocarbon dating minute amounts of bone (3–60 mg) with ECHoMICADAS OPEN
Because hard tissues can be radiocarbon dated, they are key to establishing the archaeological chronologies, palaeoenvironmental reconstructions and historical-biogeographical processes of the last 50,000 years. The advent of accelerator mass spectrometers (AMS) has revolutionized the field of archaeology but routine AMS dating still requires 60–200 mg of bone, which far exceeds that of small vertebrates or remains which hold a patrimonial value (e.g. hominid remains or worked bone artefacts). Here, we present the first radiocarbon dates obtained from minute amounts of bone (3–60 mg) using a MIni CArbon DAting System (MICADAS). An optimized protocol allowed us to extract enough material to produce between 0.2 and 1.0 mg of carbon for graphite targets. Our approach was tested on known-age samples dating back to 40,000 BP, and served as proof of concept. The method was then applied to two archaeological sites where reliable dates were obtained from the single bones of small mammals. These results open the way for the routine dating of small or key bone samples. Hard tissues (i.e. bones, teeth, antler and ivory) found in the fossil record have a tremendous informative potential relevant to the fields of archaeology, palaeoecology and the history of art and technology. Because they can be identified to the species level and radiocarbon dated, these fossil remains are key to establishing the archaeological chronologies, palaeoenvironmental reconstructions and historical-biogeographical processes (i.e. post-glacial recolonization events) of the last 50,000 years. In effect, they provide us with windows to past societies, and contribute to our knowledge of ancient human evolution and cultural development 1 , palaeoclimates 2 , paleoenvi-ronments 3 and past trade networks 4. Hard tissues contain an organic phase (mainly the protein collagen type I) embedded in a mineral phase (made of a non-stoichiometric biogenic apatite). While the exchange of inorganic carbon occurs much more readily 5, 6 , the relative chemical inertness of biopolymers makes them ideal for dating; therefore, the majority of bone radiocarbon dates are obtained from the collagen phase. The chemical integrity of this biomolecule can be assessed using simple biochemical criteria such as %C, %N and C/N ratio 7–9. The amount of collagen in fresh bone is approximately 20–25% 9, 10. As the diagenetic alteration proceeds, the quantity and quality of the collagen decreases; consequently, the sample size must increase in order to compensate for protein loss. Radiocarbon dating ancient bones can therefore prove challenging. The advent of accelerator mass spectrometers (AMS) in the eighties revolutionized the field of archaeology by allowing smaller samples to be measured. While it decreases the amount of carbon required for a radiocarbon measurement by several orders of magnitude, the AMS dating of bone collagen still requires at least 60–200 mg of bone 11–13 , depending on the protein preservation and the extraction protocol. However, this is still excessive for two classes of bone remains: (1) individual bones of small vertebrates which often weigh less than 60 mg; and (2) unique remains such as hominid bones or worked bone artefacts for which curators do not permit invasive sampling 14. The specification of sample weights used for dating is not considered necessary by the scientific community 15 and is seldom reported in publications, even when supplementary information is available (see for example refs 16–19). However, careful examination of the literature suggests that attempts at dating samples smaller than 60 mg are rare. Regarding small vertebrates, only two case studies were found: the Late Prehistoric dispersal of
14C Dating of Cremated Bones: The Issue of Sample Contamination
Radiocarbon, 2009
Recent comparative studies have proven the validity of radiocarbon dates of cremated bones. The issue of sample contamination has, however, been overlooked in most studies. Analyses of cremated bone samples has shown that in some cases, cremated bones are contaminated. This contamination is more distinct near the surface of the bones and depends on the compactness of the cremated bone as well as on the site conditions. δ13C is not a good estimator to discriminate between contaminated and uncontaminated bones. An acetic acid pretreatment is the most appropriate method to clean samples, but it is better to remove the surface and to avoid cremated bones that are not entirely white (cremation temp. <725 °).
AMS 14C Dating of Human Bones Using Sequential Pyrolysis and Combustion of Collagen
Radiocarbon, 2010
The Radiocarbon Dating Laboratory at the University of Illinois has been using the pyrolysis-combustion technique to separate pyrolysis-volatile (Py-V) or low molecular weight and pyrolysis-residue (Py-R) or high molecular weight compounds for14C dating of organic remains since 2003. We have applied this method to human collagen dating to examine the14C age difference between low and high molecular weight organic compounds. Results show that both fractions of late prehistoric period human bones from Illinois archaeological sites yield identical14C dates but that Py-V or low molecular weight fractions of Archaic period human bones appear to be slightly contaminated. In this case, Py-V components or low molecular weight collagen fraction yield older14C dates, which could result from contamination from old organic-rich sediments. The pyrolysis-combustion technique provides an economical alternative method to date bones that have not been satisfactorily dated using conventional purifica...
Radiocarbon Dating Cremated Bone: A Case Study Comparing Laboratory Methods
Radiocarbon, 2019
ABSTRACTRadiocarbon (14C) results on cremated bone are frequently published in high-ranking journals, but 14C laboratories employ different pretreatment methods as they have divergent perceptions of what sources of contaminants might be present. We found pretreatment protocols to vary significantly between three laboratories (Brussels [RICH], Kiel [KIA], and Groningen [CIO]), which all have a long history of dating cremated bone. We present a case study of 6 sets of replicate dates, to compare laboratory pretreatment protocols, and a further 16 sets of inter-laboratory replicate measurements, which compare specific steps of the conversion and measuring process. The 14C results showed dates to be reproducible between the laboratories and consistent with the expected archaeological chronology. We found that differences in pretreatment, conversion to CO2 and accelerator mass spectrometry (AMS) measurement to have no measurable influence on the majority of obtained results, suggesting t...
Assessing screening criteria for the radiocarbon dating of bone mineral
2012
Radiocarbon dating of bone mineral (carbonate in the apatite lattice) has been the target of sporadic research for the last 40 years. Results obtained by different decontamination protocols have, however, failed to provide a consistent agreement with reference ages. In particular, quality criteria to assess bone mineral radiocarbon dating reliability are still lacking.Systematic research was undertaken to identify optimal preservation criteria for bone mineral in archeological bones. Six human long bones, originating from a single site, were radiocarbon-dated both for collagen and apatite, with the level of agreement between the dates providing an indication of exogenous carbon contamination. Several techniques (Histology, FTIR, TEM, LA-ICP-MS) were employed to determine the preservation status of each sample.Research results highlight the importance of a micro-scale approach in establishing bone preservation, in particular the use of trace element concentration profiles demonstrated its potential use as a viable sample selection criterion for bone carbonate radiocarbon dating.