scholarly journals Correcting for Contamination in AMS 14C Dating

Radiocarbon ◽  
2002 ◽  
Vol 44 (2) ◽  
pp. 591-595 ◽  
Author(s):  
Ken Mueller ◽  
Paul Muzikar

When using accelerator mass spectrometry (AMS) for radiocarbon dating, it is important to correct for carbon contamination that is added to the sample and the standard during chemical processing. We derive an equation for making this correction that generalizes previous work in several ways. We treat the case in which contaminating carbon is added during both the combustion step and graphitization step. Taking this two-stage contamination process into account is particularly important when only a fraction of the CO2 produced in the combustion is graphitized. We also allow for the fact that the 13C fractions of the sample, the standard, and the contaminants may be different.

Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1403-1408
Author(s):  
G Quarta ◽  
S Malgora ◽  
M D'Elia ◽  
V Gaballo ◽  
E Braione ◽  
...  

The ancient Egyptian mummy discovered in the wooden coffin of Ankhpakhered, priest of the god Min, has been studied at CEDAD (Centre for Dating and Diagnostics) at the University of Salento, Italy. The CT scan, performed by the multidisciplinary team of the Mummy Project of Milan, highlighted unusual features of the mummy, suggesting a reuse of the sarcophagus. Furthermore, specimens were taken via endoscopy for accelerator mass spectrometry (AMS) radiocarbon dating and Fourier transform infrared (FTIR) analyses, which have been carried out at CEDAD.


Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 1371-1379 ◽  
Author(s):  
J R Southon ◽  
A L Magana

We have compared accelerator mass spectrometry (AMS) radiocarbon results on wood samples at or near the limit of 14C dating, pretreated with a standard acid-base-acid (ABA) protocol, with those obtained from cellulose prepared from the same samples by several modifications of the Jayme-Wise cellulose extraction method (Green 1963). These tests were carried out to determine the most efficient way to ensure low backgrounds in 14C measurements of well-preserved ancient wood samples.


Radiocarbon ◽  
2014 ◽  
Vol 56 (1) ◽  
pp. 95-108 ◽  
Author(s):  
Minna Väliranta ◽  
Markku Oinonen ◽  
Heikki Seppä ◽  
Sanna Korkonen ◽  
Sari Juutinen ◽  
...  

Four fen peat sequences in northern Finland were dated by the accelerator mass spectrometry (AMS) radiocarbon method in order to study past peatland dynamics and carbon accumulation patterns. Initially, plant macrofossils were used for dating. However, the dates were severely disordered, with marked inversions in all sequences. In one 140-cm peat core, for example, all ages fell within a ∼1000-yr time window. Following these unreliable results, a few bulk peat samples were dated to help assess if any of the plant macrofossil-derived dates were reliable. Bulk dates did not help to solve the problem. This study evaluates the possible sources of error but is unable to single out one clear cause. It is probable that many factors related to the fen environment, such as flooding and root intrusion, may have contributed to the errors. Peat plant macrofossils and bulk peat samples are considered to be reliable dating materials, but the examples given herein highlight the difficulties that can be associated with AMS dating of peat samples.


Radiocarbon ◽  
2013 ◽  
Vol 55 (2) ◽  
pp. 563-570 ◽  
Author(s):  
Peng Cheng ◽  
Weijian Zhou ◽  
Hong Wang ◽  
Xuefeng Lu ◽  
Hua Du

The chemical extraction of soil organic carbon (SOC) fractions from soils often does not produce satisfactory results for radiocarbon dating. In this study, a sequential pyrolysis technique was investigated. The soil was pyrolyzed at temperatures of 200, 400, 600, and 800 °C to partition organic carbon into pyrolytic volatile (Py-V) and pyrolytic residue (Py-R) fractions. The preliminary results show that the 14C dates of both fractions become progressively older as the pyrolysis temperature is increased. In addition, the ages of the Py-V fractions are consistently younger than the corresponding Py-R fractions extracted at the same temperature. Experimental results of known-age paleosol samples indicate that the Py-V fractions obtained between 600 and 800 °C yield the most reliable ages. This technique provides a new approach to improve the accuracy of 14C dating of loess-paleosol sequences.


Radiocarbon ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 385-387 ◽  
Author(s):  
David C Lowe ◽  
Gordon W Brailsford ◽  
Gregory W Drummond

A microwave oven is used to pretreat carbonate samples prior to graphitization and radiocarbon dating by accelerator mass spectrometry. The method reduces the risk of contamination of small carbonate samples and provides a fast and convenient method for the acid evolution of CO2.


Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 551-564 ◽  
Author(s):  
Ingmar Unkel ◽  
Bernd Kromer ◽  
Markus Reindel ◽  
Lukas Wacker ◽  
Günther Wagner

The people of the Paracas and Nasca cultures, the creators of the famous geoglyphs, lived in the desert of the southern coast of Peru between about 800 BC and AD 650. The archaeological chronology of these cultures has been based almost exclusively on a sequence of ceramic styles. The absolute dating of some of the style phases was supported by a few radiocarbon dates (Rowe 1967). Here, we present an absolute chronology of the Paracas and Nasca cultures based on 14C dating of more than 100 organic samples from settlement and tomb relics, as well as on material derived from geoglyph sites in the Nasca/Palpa region (south Peru). The main focus has been on Nasca period settlement centers near Palpa, Los Molinos and La Muña, the Paracas period site of Jauranga, and the Initial period site of Pernil Alto. Most of the 14C samples were dated at the accelerator mass spectrometry (AMS) facility of the ETH Zurich (Switzerland). The targets were produced in the newly built graphitization line at the Heidelberg 14C laboratory (Germany). Clay (adobe) bricks, which are quite a common building material in Peru, were successfully tested to be used for AMS 14C dating of adobe architecture in Peruvian archaeology.


Radiocarbon ◽  
2004 ◽  
Vol 46 (1) ◽  
pp. 455-463 ◽  
Author(s):  
T H Donders ◽  
F Wagner ◽  
K van der Borg ◽  
A F M de Jong ◽  
H Visscher

Sub-fossil sections from a Florida wetland were accelerator mass spectrometry (AMS) dated and the sedimentological conditions were determined. 14C data were calibrated using a combined wiggle-match and 14C bomb-pulse approach. Repeatable results were obtained providing accurate peat chronologies for the last 130 calendar yr. Assessment of the different errors involved led to age models with 3–5 yr precision. This allows direct calibration of paleoenvironmental proxies with meteorological data. The time frame in which 14C dating is commonly applied can possibly be extended to include the 20th century.


Radiocarbon ◽  
2010 ◽  
Vol 52 (3) ◽  
pp. 933-940 ◽  
Author(s):  
Shinya Yatsuzuka ◽  
Mitsuru Okuno ◽  
Toshio Nakamura ◽  
Katsuhiko Kimura ◽  
Yohei Setoma ◽  
...  

We performed accelerator mass spectrometry (AMS) radiocarbon dating and wiggle-matching of 2 wood samples from charred trunks of trees (samples A and B) collected from an ignimbrite deposit on the northeastern slope of the Baitoushan Volcano on the border of China and North Korea. The obtained calendar years for the eruption are cal AD 945–960 for sample A and cal AD 859–884 and cal AD 935–963 for sample B in the 2-σ range. These results are unable to determine the precise eruption age. The reason for the difference in reported ages may be due to volcanic gas emission prior to the huge eruption.


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