This Radiocarbon special double issue is dedicated to the “6th International Radiocarbon and Archaeology” Symposium that took place in Paphos, Cyprus – a real Mediterranean crossroads. The conference demonstrated that the inter- and intra-disciplinary nature of radiocarbon and archaeology research is no longer limited to an “exchange” of samples and dates, but is rapidly becoming an integrated whole, with the same student or researcher working in both worlds: radiocarbon and archaeology.

Lake Mývatn and several smaller lakes in northern Iceland were formed by the large Holocene lava flow of the Younger Laxá Lava (YLL). The age of the YLL was estimated by tephrochronology at 1800–2300 BP (Thorarinsson 1951). Conventional radiocarbon dating of charred vegetation beneath the YLL (Thorarinsson 1964) yielded uncalibrated ages of 1940 ± 270 14C yr BP (Yale), 2110 ± 140 14C yr BP (Copenhagen), and 1990 ± 50 14C yr BP (Winnipeg). Ongoing palcolimnological research at Lake Mývatn requires a more precise age estimation of the YLL. Charcoal samples from beneath the YLL were collected at Presthvammur in 2007 and analyzed by accelerator mass spectrometry (AMS) 14C measurements. The reliability of the conventional 14C ages of the samples Yale, Copenhagen, and Winnipeg was re-evaluated, applying criteria from Pettit et al. (2003) and Graf (2009). The result of AMS 14C measurement (2170 ± 38 cal yr BP) underpins the local tephrochronology and provides a reliable age of the YLL and Lake Mývatn.

Jean-François Saliège passed away on Friday, 1 June 2012, following a heart attack at age 68. Jean-François was born in Chartres and spent his entire career in Paris, a city that he particularly enjoyed. He was hired in 1965 as a junior technician at the Laboratoire de Géologie Dynamique de la Faculté des Sciences de Paris at La Sorbonne University (Director Louis Glangeaud), where he participated in the creation of the radiocarbon and mass spectrometry laboratory under supervision of René Létolle, Jean-Charles Fontes, and Colette Vergnaud-Grazzini. In 1975, he moved to the University of Paris VI and worked more specifically with J-C Fontes in the 14C laboratory as an engineer. In 1981, he helped J-C Fontes to create the Hydrology and Isotope Geochemistry lab at Orsay University. The following year, he returned to the University of Paris VI and joined the team led by Colette Vergnaud-Grazzini at the Laboratoire de Géologie Dynamique, where Jean-François set up the new stable isotope and radiocarbon lab. Between 1990 and 2008, he continued to work at the University of Paris VI at the LODYC lab (Dir. Lilianne Merlivat), then at the LOCEAN lab (Dir. Laurence Eymard) on Catherine Pierre's team.

We present the first radiocarbon dates from previously unrecorded, secondary burials in the Cardamom Mountains, Cambodia. The mortuary ritual incorporates nautical tradeware ceramic jars and log coffins fashioned from locally harvested trees as burial containers, which were set out on exposed rock ledges at 10 sites in the eastern Cardamom Massif. The suite of 28 14C ages from 4 of these sites (Khnorng Sroal, Phnom Pel, Damnak Samdech, and Khnang Tathan) provides the first estimation of the overall time depth of the practice. The most reliable calendar date ranges from the 4 sites reveals a highland burial ritual unrelated to lowland Khmer culture that was practiced from cal AD 1395 to 1650. The time period is concurrent with the 15th century decline of Angkor as the capital of the Khmer kingdom and its demise about AD 1432, and the subsequent shift of power to new Mekong trade ports such as Phnom Penh, Udong, and Lovek. We discuss the Cardamom ritual relative to known funerary rituals of the pre- to post-Angkorian periods, and to similar exposed jar and coffin burial rituals in Mainland and Island Southeast Asia.

At Tell Sabi Abyad, Syria, radiocarbon dating previously provided a robust chronology for the 7th–early 6th millennium BC, the Late Neolithic. The continuous inhabitation spans the 8.2 ka climate event. This chronology has been used here in a study of stable isotope (13C and 15N) data of animal bones. This is the first isotope study undertaken on material from this area. The results are used to explore diet and therefore animal management practices through the period ∼6800–5800 BC. A climatic signal could not be detected in the bone samples.

Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Δ14C excess from known-age annual increments of the long-lived bivalve mollusk Arctica islandica from 4 sites across the coastal North Atlantic (German Bight, North Sea; Troms⊘, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of 14C at the air-sea boundary, 14C content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Δ14C excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration scries for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

This paper describes a method for effective separation of the pure binder fraction of lime mortars for reliable radiocarbon dating. The methodology allows removal of the detrital carbonate fraction and the unburnt limestone particles, obtaining particles of under 1 μm. The extracted fraction ensured that all carbonate has been generated by slaked lime carbonation. Consequently, the measured carbon corresponds to atmospheric carbon. The proposed method allows to obtain pure datable binder, simplifying considerably the performance of radiometric measurements because dating other grain-size fraction is unnecessary. In order to prove the effectiveness of binder refining, the extraction method has been applied to 5 lime mortars of different archaeological periods from the perimeter walls of Santa María la Real parish church (Zarautz, northern Spain).

A sample with a radiocarbon concentration estimated to be greater than 105 times Modern was inadvertently graphitized and measured in the Xi'an AMS system last year. Both the sample preparation lines and the ion source system were seriously contaminated and a series of cleaning procedures were carried out to remove the contamination from them. After repeated and careful cleaning as well as continuous flushing with dead CO2 gas, both systems have recovered from the contamination event. The machine background is back to 2.0 x 10–16 and the chemical blank is beyond 50 kyr.

One of the greatest challenges of contemporary archaeology is to synthesize the large amount of radiocarbon and archaeological data into a useful dialogue. For the late Epipaleolithic and the Early Neolithic of the Near East, many 14C ages have been published without precise stratigraphic documentation. Consequently, for archaeological age models we often must use some more elementary approaches, such as probabilistic summation of calibrated ages. The stratigraphy of Körtik Tepe allows us for the first time to study an extended series of 14C ages of the earliest Holocene. In particular, we are able to analyze the data according to stratigraphic position within a well-documented profile. However, because of a plateau in the 14C age calibration curve at the transition from the Younger Dryas to the Early Holocene, dates of this period can be interpreted only if an extended sequence of dates is available. Due to problems remaining in the calibration procedure, the best way to achieve an interpretation is to compare the results of different 14C calibration software. In the present paper, we use the results of the calibration programs OxCal and CalPal. This approach has important implications for future age modeling, in particular for the question of how to date the transition from the Epipaleolithic to the PPNA precisely and accurately.

Paleoenvironmental and paleogeomagnetic tracing studies from Chinese loess 10Be have progressed in recent years (Zhou et al. 2007a,b, 2010). In this approach, 10Be flux determined from sediment concentration and accumulation rate may be used to recover information about paleomonsoon rainfall rates as well as past variations in the geomagnetic field strength. However, these methods require that a correction be made for residual undecayed 10Be in remobilized dust. To better understand the feature of the 10Be signals related to the remobilized dust, we report the first observational study on 10Be concentration of modern falling dust using the 3MV multi-element accelerator mass spectrometer (AMS) in the Xi'an AMS Center. Ten samples collected at Ansai observation station (109°19′E, 36°51′N) in northern China from May 2008 to June 2009 are measured along with 3 chemical blanks. The results clearly show that the 10Be content of modern falling dust is relatively uniform, with a mean value of 1.21 x 108 atoms/g, a measurement similar to that of Chinese loess (Zhou et al. 2007a) and to the value found in the study by Shen et al. (2009) on dust 10Be falling near Dingbian, China (1.25 ± 0.06 x 108 atoms/g). Despite the fact that modern dust flux is much higher in spring relative to summer in northern China, 10Be concentration in falling dust remains fairly constant. In addition, we find that dust 10Be concentration is roughly independent of the local precipitation changes. This feature might be considered as an analogue to improve our understanding on the fundamental information of the source component contained in loess 10Be records and its spatial/temporal distribution features.

The Neolithic site KS043, excavated by the Institut français d'archéologie orientale (IFAO), is situated in the southern basin of the Kharga Oasis (Egypt). It is one of the very few stratified prehistoric sites of the eastern Sahara. The archaeological remains were found near artesian springs that provided water for pastoralists during the dry Middle Holocene. In situ settlement features provided well-preserved material (charcoal, ashy sediment, ostrich eggshell) sufficient to perform radiocarbon dating in the IFAO laboratory in Cairo by the conventional liquid scintillation method. In 2 cases, ostrich eggshell and charcoal within the same in situ context gave significantly different results of, respectively, ∼600 and ∼1200 yr younger dates for the ostrich eggshells. The strong discrepancy is here highlighted for the first time and we suggest that it may be linked with postdepositional phenomena in the vicinity of the artesian springs. A thorough review of 14C dates available for the Holocene in eastern Sahara shows that ostrich eggshells have been widely used. They seem slightly more prone to be discarded than other material but were never the object of a particular study in this context. Bayesian modeling shows that the Neolithic occupation at site KS043 spans a range from 5000 to 3950 cal BC (and concentrated around 4600–4350 cal BC). Characteristic flint tools and pottery relate this occupation to the end of the Neolithic and show links with the Tasian culture, confirming the timing of the presence of this cultural complex in the desert before its appearance in the Nile Valley.

Specific activities of radiocarbon in annual tree rings corresponding to 1980-2009 are reported for a pine tree located 2 km from the Qinshan Nuclear Power Plant (Qinshan NPP), China. While a negligible enhanced 14C activity due to operation of the Qinshan NPP Plant I is evident, a relative increase (1.8–62.6 Bq/kg C) was observed in the specific activity after operation of the Qinshan NPP Plant II in 2002 and Plant III in 2003. The enhanced values were primarily affected by the 14C discharged from Plant III (CANDU-type reactor), and a good correlation was found between the 14C discharged from Plant III in the growing season and the 14C excess value. The excess 14C activities peaked in 2005 (at 302.0 Bq/kg C, which is 62.6 Bq/kg C above the “clean air” 14C level), and then declined due to the improvement in 14C discharge management of Plant III. In 2009, the 14C-specific activity was near the background level.

Archaeological investigations at Halai, a small city-state on the sea coast of East Lokris in Greece, have been carried out since 1986 by the Cornell Halai and East Lokris Project (CHELP). The town's acropolis, first inhabited in the Neolithic period, was in Greco-Roman times a political and cultural center controlling and serving a considerable territory. Radiocarbon dating of charred material unearthed from Neolithic deposits indicate that the Neolithic occupation probably lasted from about 6000 to 5300 BC. Details of dating are somewhat problematic, however, because of outlying determinations and lack of close agreement between determinations from the same or stratigraphically comparable material.

The development of sociopolitical complexity at Tiwanaku around AD 500 was one of the major episodes of social change in the history of the Lake Titicaca Basin. It was the result of poorly understood processes that took place at a series of ceremonial centers in the preceding centuries. The history of Tiwanaku during this time is especially unclear, because the only radiocarbon dates are from excavations whose details were never completely published. Despite this, there is consensus that Tiwanaku was founded around 300 BC. A re-evaluation of the archaeological context of each of these dates shows many of them to be unreliable. Two Bayesian models from independent excavations agree that Tiwanaku was in fact founded centuries later, most likely around AD 110 (50-170, 1σ). This has important implications for widely used monolith and ceramic sequences, as well as understanding the rise of Tiwanaku and other archaic states.