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The Ongamira Valley (Córdoba, Argentina) shows a persistent occupational history of its territory. Even one of the first Argentinian radiocarbon (14C) dates was calculated in this valley; for 70 years, the chronology was based on relative dates (stratigraphy and its cultural content). For this reason, since 2010 a 14C dating program has been developed focusing on the chronology of eight of the 60 sites identified so far for the valley. This work reports the outcomes of this program with 27 new dates. These data have been related to characteristics of the material culture, use of space and mobility of hunter-gatherer societies. The results have allowed us to bring new insights into a continuous occupation of the valley since the Middle Holocene according to the human peopling models proposed. It has also been possible to provide greater chronological precision to various activities related to feeding practices, use of space associated with rock-shelters, palaeoenvironmental changes and incorporation of new technologies into daily practices.
Areas affected by routine radiocarbon (14C) discharges from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) and accidental releases in March 2011 were investigated by analysis of cores from Japanese cypress and cedar trees growing at sites 9 and 24 km northwest of the plant. 14C concentrations in tree rings from 2008–2014 (before and after the accident) were determined by accelerator mass spectrometry, with 14C activities in the range 231–256 Bq kg−1 C. Activities during the period 2012–2014, after FDNPP shutdown, represent background levels, while the significantly higher levels recorded during 2008–2010, before the accident, indicate uptake of 14C from routine FDNPP operations. The mean excess 14C activity for the pre-accident period at the sites 9 and 24 km northwest of the plant were 21 and 12 Bq kg−1 C, respectively, indicating that the area of influence during routine FDNPP operations extended at least 24 km northwest. The mean excess tree-ring 14C activities in 2011 were 10 and 5.8 Bq kg−1 C at 9 and 24 km northwest, respectively, documenting possible impact of the FDNPP accident on 14C levels in trees.
This study attempts to reconstruct food habits through carbon (C) and nitrogen (N) isotope analysis and C/N analysis of charred residues inside pottery from the Primorye in the Russian Far East (Luzanova Sopka 2, Sergeyevka 1, Boisman 2, and Vetka 2 sites). Dates were obtained that were from the later stages of the Rudnaya culture (6980–6485 BP, 7800–7400 cal BP), proto-Boisman type (6760–6330 BP, 7600–7300 cal BP), Boisman culture (6155–4720 BP, 7100–5400 cal BP), and Vetka culture (6030–5870 BP, 6900–6700 cal BP). There are major differences in the carbon and nitrogen isotope ratios between inland sites (δ13C –26.9 to –30.0‰, δ15N 7.6 to 9.3‰) and coastal sites (δ13C –18.1 to –24.2‰, δ15N 9.5 to 14.9‰). The results show that the diet of inland cultures consisted primarily of freshwater fish and terrestrial animals and plants, whereas that of coastal cultures consisted mainly of marine organisms.
Over 30 funerary bundles were excavated in 2005 from a large chamber tomb at the prehispanic religious center of Pachacamac on the central coast of Peru. The largest and most elaborate bundle was found in the innermost part of the tomb, tightly surrounded by other bundles. We hypothesized that this bundle contained the deceased leader of a social group whose members collectively cared for their ancestor's bundle (for example, by rewrapping it) and continued to use the tomb to inter deceased individuals from subsequent generations. We tested this hypothesis by dating samples from different layers of the wrapping materials and soft tissue from the bodies and conducting a Bayesian analysis of the resultant dates. We determined carbon and nitrogen isotope ratios in the diet of the interred individuals to correct for marine reservoir effects. Our findings suggest that (1) rewrapping did not occur; (2) the tomb was used for over 500 years starting at cal A.D. 1000; and (3) existing bundles were reshuffled each time new bundles were introduced. Overall, diverse lines of evidence indicate that the tomb had a complex use history and contained individuals with diverse geographical and social origins. This challenges conventional thinking about the social and chronological significance of coexisting bundles in large tombs.
This study applied compound-specific radiocarbon analysis (CSRA) to a 186-m-long sediment core (U1357A) taken from Adélie Basin located on the continental shelf off Wilkes Land, East Antarctica. The CSRA targeted C16 fatty acid as well as C16., fatty acid and cyclopheophorbide-a-enol isolated from the sediment. Due to their high degradation rate, these compounds are expected to occur in low abundances in relict organic matter deposited at this site. Twelve compound-specific (CS) 14C ages were obtained that are mostly consistent with their stratigraphic order. The CS 14C results of all samples are Holocene in age (9800 to 440 cal BP). These results suggest that significant sedimentation started ∼10,000 cal BP. Moreover, the data suggest that 14C measurements of C16:1 fatty acid and cyclopheophorbide-a-enol are useful for dating sediments from the Southern Ocean.
This study reconstructs food habits through carbon and nitrogen isotope analysis, and C/N analysis of charred residues inside pottery from Amur River sites in Russia (Goncharka 1 site, Novotroitskoe 10 site, Kondon 1 site) and in Hokkaido, Japan (Taisho 3 site, Yachiyo A site). We obtained dates from 12,330 to 7920 BP for these sites. There are major differences in the carbon and nitrogen isotope ratios between the Taisho 3 site (δ13C: -21.7 to -24.1; δ15N: 11.9–14.7%) and the other sites (δ13C:-22.0 to -27.1%; δ15N: 7.1–13.1%), suggesting that the people of the Taisho 3 site made use of anadromous fish such as salmonids and some species of trout, as well as marine resources. The dates from the other sites except Taisho 3 were assumed to be from a mixture of marine foods, C3 plants and terrestrial animals, and freshwater fish. The food boiled in the pots also indicated a high dependence on marine resources during the initial stages of the emergence of pottery.
Shallow-water tropical corals can be used to calibrate the radiocarbon timescale. In this paper, we present a new data set based on the comparison between 14C ages and U-Th ages measured in fossil corals collected offshore the island of Tahiti during the Integrated Oceanic Drilling Program (IODP) Expedition 310. After applying strict mineralogical and geochemical screening criteria, the Tahiti record provides new data for 2 distinct time windows: 7 data for the interval between 29 and 37 cal kyr BP and 58 for the last deglaciation period, notably a higher resolution for the 14–16 cal kyr BP time interval. There are 3 main outcomes of this study. First, it extends the previous Tahiti record beyond 13.9 cal kyr BP, the oldest U-Th age obtained on cores drilled onshore in the modern Tahiti barrier reef. Second, it strengthens the data set of the 14–15 cal kyr BP period, allowing for better documentation of the 14C age plateau in this time range. This age plateau corresponds to a drop of the atmospheric 14C synchronous with an abrupt period of sea-level rise (Melt Water Pulse 1 A, MWP-1 A). The Tahiti 14C record documents complex changes in the global carbon cycle due to variations in the exchange rates between its different reservoirs. Third, during the Heinrich event 1, the Tahiti record disagrees with the Cariaco record, but is in broad agreement with other marine and continental data.
This study reports radiocarbon dates of more than 30 samples of charred residues on pottery sherds of the Incipient Jomon period. The ages of Linear-relief (Ryukisenmon) pottery were 15,300–13,700 cal BP, with great differences among the samples. The pitted decoration (Enkomon), Nail-impressed (Tsumegatamon), and pressing and dragging (Oshibikimon) types date to 13,800–12,400 cal BP. For pottery of the same type, differences among sites were large. At the Unokiminami site, the impressed cord mark (Oatsu Jomon) is the main pottery type, including Nail-impressed. The latter shows a slightly older age. Stable isotope and elemental analyses were used to ascertain the origin of charred residues on the pottery. In the data set of Jomon pottery of the oldest type, residues consisting only of cooked nuts were found. However, Jomon people, even from early times, are thought to have cooked mixed plant and animal ingredients, including marine products.
We present the water column profiles (surface to 2000 m depth) for dissolved inorganic radiocarbon (14CDIC) from 2 stations in the Kuroshio region including the Kuroshio large meander (LM) of 2004–2005. Surprisingly, the Δ14CDIC value varied up to 125‰ in the intermediate layer, especially near 600 m depth. In addition, the Δ14CDIC value was approximately − 150‰ at 200 m depth at the northern station of Kuroshio in August 2005. This value is ∼100‰ less than other Δ14CDIC values for the same depth. In comparison, the Δ14CDIC water column profiles for the southern station of Kuroshio and GEOSECS station 224 decrease down to 600 m depth and were similar below 600 m depth. Our results suggest that strong upwelling associated with the Kuroshio LM has a powerful influence on the Δ14CDIC water column profiles in the study region.
In this study, molluscan shells housed at the University Museum, the University of Tokyo, provided a new set of region-specific correction values (ΔR) for the western Pacific, in particular for the central part of the main islands in the Japanese Archipelago and the southwest islands of Japan. The values of 40 total samples were calculated from 11 regions. North of the main islands and in the Ryukyu Islands, the mean ΔR values showed comparatively small values, 5–40 14C yr; in the central part of the main islands, these values were 60–90 14C yr.
Radiocarbon ages of Choukai Jindai cedar tree rings growing in the excess era of 14C concentrations during 2757–2437 cal BP were measured using 2 types of 14C measurement methods, i.e. liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The difference between the 2 methods is 3.7 ± 5.2 14C yr on average for 61 single-year tree rings, indicating good agreement between the methods. The Choukai data sets show a small sharp bump with an average 14C age of 2497.1 ± 3.0 14C yr BP during 2650–2600 cal BP. Although the profile of the Choukai LSC data set compares well with that of IntCal04, having a 14C age difference of 4.6 ± 5.3 14C yr on average, the Choukai LSC 14C ages indicate variability against the smoothed profile of IntCal04.
We have developed accelerator mass spectrometry (AMS) measurement techniques for ultra small-size samples ranging from 0.01 to 0.10 mg C with a new type of MC-SNICS ion source system. We can generate 4 times higher ion beam current intensity for ultra-small samples by optimization of graphite position in the target holder with the new ionizer geometry. CO2 gas graphitized in the newly developed vacuum line is pressed to a depth of 1.5 mm from the front of the target holder. This is much deeper than the previous position at 0.35 mm depth. We measured 12C4+ beam currents generated by small standards and ion beam currents (15–30 μA) from the targets in optimized position, lasting 20 min for 0.01 mg C and 65 min for 0.10 mg C. We observed that the measured 14C/12C ratios are unaffected by the difference of ion beam currents ranging from 5 to 30 μA, enabling measurement of ultra-small samples with high precision. Examination of the background samples revealed 1.1 μg of modern and 1 μg of dead carbon contaminations during target graphite preparation. We make corrections for the contamination from both the modern and background components. Reduction of the contamination is necessary for conducting more accurate measurement.
129I/127I and 14C/12C depth profiles were compared for the surface 30-cm layer of soil samples (Andisols) collected from Shimokita Peninsula, northeastern Japan, in November 2005. The 129I/127I and 14C/12C profiles have a clear correlation, even taking into account that the data include samples collected from different sites with different surface histories. These results, and considering that 14C/12C can be regarded as a proxy of the original depth in stable soil, show the diversity of the 129I/127I ratio at the surface among the sites, indicating variations in the thicknesses of the layers recently removed. At one of the sampling sites (P003-1), the Δ14C value measures ∼110‰ near the surface, which is indicative of anthropogenic 14C produced by atmospheric testing of nuclear weapons during the late 1950s and early 1960s. This site has experienced no disturbances for at least the past 50 yr. The relatively high activity of 129I (0.8 mBq/kg) and the 129I/127I ratio (7 x 10–9) observed at the top layer of this site can be considered a “representative value” when considering the anthropogenic iodine transfer from the atmosphere to the ground. The observations also support 2 separate modes of 129I migration in the soil: i.e. “topmost quick diffusion” and “subsurface relatively slow migration process.” Even in the “subsurface relatively slow migration zone,” the 129I/127I ratio was still orders higher than the pre-anthropogenic natural level.
We measured the radiocarbon ages of 165 single-year tree rings from a Japanese Choukai Jindai cedar using accelerator mass spectrometry (AMS). By wiggle-matching the Choukai_AMS data set to the IntCal04 calibration data using OxCal v 3.10 and using the variation of the correlation coefficients between the Choukai_AMS and IntCal04 data sets, we precisely re-estimated that the 321 Choukai Jindai cedar tree rings range from 780 to 460 cal BC with an accuracy of 8 yr. The Choukai_AMS data set is older than the 3 raw data sets of European tree rings that comprise IntCal04. The Belfast and Seattle data sets are younger by −21.3 ± 5.5 and −22.7 ± 5.6 14C yr, respectively. The Choukai Jindai cedar is ∼22 14C yr older than the European tree rings, which is equivalent to an offset of −2.8‰ in 14C. In addition, the Choukai_AMS data set correlates well with the Belfast and Seattle data sets, with correlation coefficients of 0.89 and 0.68, respectively, between the temporal profiles. Hence, the temporal profile of the Choukai 14C ages shows a global variation.
We have determined the radiocarbon ages for 40-yr-interval tree rings in 2 fossil trees of the Towada Hachinohe buried forest, northeastern Honshu Island, Japan. The 14C ages range from 13.0 to 13.3 kyr BP (about 15.5 cal kyr BP). The weighted average of the 14C age of the outermost 5 rings is 13,133 ± 33 BP, which can be calibrated to 15,363–15,679 cal BP by using the IntCal04 standard curve (Reimer et al. 2004). The estimated δ14C values range between 265 and 300% and show approximately sinusoidal fluctuation of an indicated ∼200-yr cycle, perhaps reflecting contemporary solar activity change. Comparison between the tree 14C profile and the Cariaco Basin 14C record provides further information on the accurate date of the Towada Hachinohe buried forest and the eruption that produced it. 14C analysis of tree rings from the buried forest may contribute to the construction of a better 14C calibration curve and the elucidation of solar activity change during the last glacial period, as well as possible global and regional impacts of the huge eruption from Towada Volcano.
In order to investigate the regional atmospheric radiocarbon offset, accelerator mass spectrometry (AMS) 14C measurements were made on 5-yr increments of a Japanese wood sample dendrochronologically dated to 820–436 BC. The 14C data from the Japanese tree-ring samples were compared with the IntCal04 calibration curve (Reimer et al. 2004). In most parts, the differences between IntCal04 and 14C dates in the Japanese tree-ring samples were within experimental statistical errors. At around 680 BC, however, significant differences of up to 100 14C yr were observed. These differences may indicate either regional offsets in Japan or the short-term fluctuation of a subdecadal timescale in atmospheric 14C variations.
We have measured the radiocarbon ages of 43 consecutive single-year tree rings using accelerator mass spectrometry (AMS) with a statistical accuracy of ∼2.3%. AMS 14C ages of the 36 viable samples are between 2708 and 2666 cal BP, a period in which the Δ14C of the IntCal04 curve (Reimer et al. 2004) shows an enhancement. The 14C ages of the samples are scattered with a Gaussian distribution around the interpolated IntCal04 calibration curve. The time profile of the deviations of the 36 14C ages from the interpolated IntCal04 calibration curve indicates a linear trend and a characteristic variability rather than a random fluctuation around the curve. The trend indicates a higher gradient than that of the interpolated IntCal04 calibration curve. The profile implies a periodic variation of approximately 11 yr and an amplitude of roughly 18 14C yr.
We have measured the radiocarbon concentrations in single-yr tree rings of old wood by accelerated mass spectrometry (AMS) using a multicathode. The 14C concentrations of 10 single-yr tree rings were measured in 100 tree rings at intervals of 10. For each single-yr tree-ring sample, typically 80 measurements of the 14C concentrations were carried out using multicathodes. The sample standard deviations indicated that there are other fluctuations of typically 1.5%, in addition to the fluctuation of the Poisson counting statistics which is typically 3% for each measurement. The average 14C date of the tree rings was 22,130 ± 306 BP for all 624 data of single-yr tree-ring samples measured by the multicathodes. From the calibration data of Lake Suigetsu, the calendar dates of these 100 tree rings were located between 25,400 cal BP and 26,150 cal BP. The 14C dates changed between 21,979 BP and 22,272 BP, with an error of approximately 50 BP, corresponding to a precision of approximately 0.5%. There was a step with a change of approximately 144 BP for each 10 yr in the time profile.
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