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Modeling Atmospheric 14 C Influences and 14 C Ages of Marine Samples to 10,000 BC
Abstract
The detailed radiocarbon age vs calibrated (cal) age studies of tree rings reported in this Calibration Issue provide a unique data set for precise 14C age calibration of materials formed in isotopic equilibrium with atmospheric CO2. The situation is more complex for organisms formed in other reservoirs such as lakes and oceans. Here the initial specific 14C activity may differ from that of the contemporaneous atmosphere. The measured remaining 14C activity of samples formed in such reservoirs not only reflects 14C decay but also the reservoir 14C activity. Model calibrations are made for the global marine response for surface (0-75m) thermocline (75-1000m) and deep (1000-3800m) waters. Model calculations yield information of atmospheric Δ14C values, production rates, Q, and alternative changes in oceanic mixing rates Kz, and demonstrate the validity of the production modulation approach to calibration. -from Authors
... Negative ΔR values reflect lower MRE for the studied region compared with the global marine model and vice versa. Local ΔR values can be determined from a variety of approaches (the most common include 14 C dating known-age marine samples; 14 C dating paired contemporaneous marine/terrestrial samples; and paired 14 C/U-series dating of corals) (Stuiver and Braziunas 1993;Hua et al. 2020). To avoid ambiguity, here we use the term ΔR when discussing local correction values in general and ΔR XX when denoting offsets to a specific calibration curve (i.e., ΔR 20 when referring to a ΔR value derived from and for use with the Marine20 marine calibration curve) (see Heaton et al. 2023). ...
... Samples must have reliable provenance data (i.e., geographic location). There are many complexities that affect samples at the local level, such as upwelling, tidal flushing, terrestrial runoff effects from freshwater input, and local geology (Dye 1994;Stuiver and Braziunas 1993;Ulm 2002;Ulm et al. 2009). As some species have wide tolerance levels, detailed collection provenance is essential. ...
Studies of pre-bomb mollusks live-collected around the Australian coastline have concluded that near-shore marine radiocarbon reservoir effects are small and relatively uniform. These studies are based on limited samples of sometimes dubious quality representing only selective parts of Australia’s lengthy coastline. We systematically examine spatial variability in the marine radiocarbon reservoir effect (ΔR) through analysis of 292 live-collected mollusk samples across the Australian mainland coasts and near-shore islands subject to strict selection criteria. This study presents 233 new ΔR values combined with an evaluation of 59 previously published values. Results demonstrate significant spatial variability in marine radiocarbon reservoir effects across the study region. ΔR values range from 68 ± 24 ¹⁴ C years off the Pilbara region of Western Australia to –337 ± 46 ¹⁴ C years in the southern Gulf of Carpentaria in Queensland. Most sets of local values exhibit internal consistency, reflecting the dominant influence of regional oceanography, including depletion in ΔR values southwards along the eastern Australian coastline coincident with the East Australian Current. Anomalous values are attributed to inaccurate documentation, species-specific relationships with the carbon cycle and/or short-term fluctuations in marine radiocarbon activities. To account for the heterogeneous distribution of marine ¹⁴ C, we recommend using a location specific ΔR value calculated using the Australian ΔR Calculator, available at: https://delta-r-calc.jcu.io/ .
... Unlike the PDO, which has key signals over the North Pacific, the MPO has key signals over the entire Pacific and results in synchronous multi-decadal climate patterns over pan-Pacific areas. Solar irradiance reconstructions were also employed, specifically those derived from 14 C and 10 Be (Bard et al., 2000;Crowley, 2000;Stuiver and Braziunas, 1993). ...
... We have replaced this material with a homogeneous coral carbonate standard, resulting in revising uncertainties of previously reported materials downwards, typically to 15-20 years BP. ΔR 20 was calculated following (Stuiver and Braziunas 1993). ...
Marine radiocarbon ( ¹⁴ C) ages are an important geochronology tool for the understanding of past earthquakes and tsunamis that have impacted the coastline of New Zealand. To advance this field of research, we need an improved understanding of the radiocarbon marine reservoir correction for coastal waters of New Zealand. Here we report 170 new ΔR 20 (1900–1950) measurements from around New Zealand made on pre-1950 marine shells and mollusks killed by the 1931 Napier earthquake. The influence of feeding method, living depth and environmental preference on ΔR is evaluated and we find no influence from these factors except for samples living at or around the high tide mark on rocky open coastlines, which tend to have anomalously low ΔR values. We examine how ΔR varies spatially around the New Zealand coastline and identify continuous stretches of coastline with statistically similar ΔR values. We recommend subdividing the New Zealand coast into four regions with different marine reservoir corrections: A: south and western South Island, ΔR 20 –113 ± 33 yr, B: Cook Strait and western North Island, ΔR 20 –171 ± 29 yr, C: northeastern North Island, ΔR 20 –143 ± 18 yr, D: eastern North Island and eastern South Island, ΔR 20 –70 ± 39 yr.
... A total of 11 samples including plant material, wood debris and marine gastropods were extracted from the cores for AMS 14 C dating analysis (Table 1) at Beta Analytic Radiocarbon Dating Laboratory, Florida, US. All radiocarbon dates were calibrated in the CALIB 8.2 (Stuiver and Braziunas, 1993;Stuiver et al., 2020) using INTCAL20 for organic materials and using MARINE20 for marine shells (Heaton et al., 2020) with the ΔR of − 75 +/− 44 (Southon et al., 2002;Bevington and Robinson, 2003). The age-depth models were developed using Bchron under R environment (Haslett and Parnell, 2008; Fig. 3). ...
Tis paper argues that what is presently considered normal practice in
Romanian archaeology is too narrow with respect to the variety of data
that can potentially be collected from the feldwork as well as later, in
the laboratory, from the archaeological material, and that this is caused
by the dominance of the culture-historical paradigm, which is ultimately limited to the identifcation of social groups and does not provide the theoretical tools necessary for the meaningful integration of these new categories of data (i.e., it cannot use them to explain how societies work). Further, it argues that the scope of what is presently seen as standard knowledge in Romanian archaeology should be very much widened to include whatever domain of the social and natural sciences is necessary in order to provide better archaeological results. It also draws attention to
the consequences of the delay of such a change in archaeology: the risk of losing precious information in the feld, in a period when expanding infrastructure works and construction of residential areas are destroying archaeological sites at a quicker rate than in earlier times.
At the same time, the paper highlights that the changes needed in Romanian archaeology cannot be left to archaeologists at the individual level alone, and that an extensive process of institutional development is absolutely necessary.
El uso y la gestión de la montaña en la sierra de Aralar han podido ser documentados desde el Neolítico hasta nuestros días en restos antrópicos que van desde megalitos hasta minas, pasando por el aprovechamiento de cuevas y diversos tipos de asentamientos en forma de cabañas. Estas evidencias han podido ser inventariadas, estudiadas y datadas en muchos casos. La ganadería, estacional, es la principal actividad relacionada con estas estructuras, y las condiciones ambientales, culturales y económicas han ido determinando sus características. Ha sido necesaria una metodología multidisciplinaria que apoyara a la arqueología para ir estudiando desde 1993 los a veces esquivos restos dejados por las personas que han gestionado los recursos de la zona.
The sole purpose of this paper is to present a previously published 14 C data set to which minor corrections have been applied. All basic information previously given is still applicable (Pearson & Stuiver 1986). The corrections are needed because 14 C count-rate influences (radon decay in Seattle, a re-evaluation of the corrections applied for efficiency variation with time previously unrecognized in Belfast) had to be accounted for in more detail. Information on the radon correction is given in Stuiver and Becker (1993). The Belfast corrections were necessary because the original correction for efficiency variations with time was calculated using two suspect standards (these were shown to be suspect by recent observations) that overweighted the correction. A re-evaluation (Pearson & Qua 1993) now shows it to be almost insignificant, and the corrected dates (using the new correction) became older by about 16 years.
Count rates, representing the rate of 14 C decay, are the basic data obtained in a 14 C laboratory. The conversion of this information into an age or geochemical parameters appears a simple matter at first. However, the path between counting and suitable 14 C data reporting (table 1) causes headaches to many. Minor deflections in pathway, depending on personal interpretations, are possible and give end results that are not always useful for inter-laboratory comparisons. This discussion is an attempt to identify some of these problems and to recommend certain procedures by which reporting ambiguities can be avoided.
New AMS and TIMS results presented here confirm the precision and accuracy of the U-Th geochronometer applied to scleractinian corals. As shown before, the 14C ages are systematically younger than true ages during most of the 14C range except for the brief period between 500 and 2500 cal BP. This sets the relative duration of the Holocene between 11 200 and 11 500 cal yr, and the Younger Dryas chronozome corresponds to c10 000-1600 cal yr. The AMS 14C age of the early Bolling δ18O shift varies between 12 700 and 12 5000 BP which corresponds to U-Th ages between 14 700 and 14 500 BP. Broecker has proposed that this benchmark could be used to correlate records but problems may result because 12 700 14C yr BP corresponds to another radiocarbon age plateau. -K.Clayton
The radiocarbon ages of dendrochronologically dated wood spanning the AD 1950–6000 BC interval are now available for Seattle (10-yr samples, Stuiver & Becker 1993) and Belfast (20-yr samples, Pearson, Becker & Qua 1993; Pearson & Qua 1993). The results of both laboratories were previously combined to generate a bidecadal calibration curve spanning nearly 4500 years (Stuiver & Pearson 1986; Pearson & Stuiver 1986). We now find that minor corrections must be applied to the published data sets, and therefore, give new bidecadal radiocarbon age information for 2500–6000 BC, as well as corrected radiocarbon age averages for AD 1950–500 BC. Corrected average 14 C ages for the 500–2500 BC interval are given separately (Pearson & Stuiver 1993). The Seattle corrections (in the 10–30 14 C-yr range) are discussed in Stuiver and Becker (1993), whereas Pearson and Qua (1993) provide information on Belfast corrections (averaging 16 yr). All dates reported here are conventional radiocarbon dates, as defined in Stuiver and Polach (1977). Belfast 14 C ages back to 5210 BC were obtained on wood from the Irish oak chronology (Pearson et al. 1986). Wood from the German oak chronology (Becker 1993) was used by Belfast for the 5000–6000 BC interval. For the overlapping interval (5000–5210 BC), Belfast reports weighted Irish wood/German wood 14 C age averages. The Seattle 14 C ages for the AD interval were either on Douglas fir wood from the US Pacific Northwest, or Sequoia wood from California (Stuiver 1982). The BC materials measured in Seattle were mostly part of the German oak chronology. Thirteen samples (5680–5810 BC) from the US bristlecone pine chronology (Ferguson & Graybill 1983) were measured in Seattle as well. Here, the final Seattle decadal 14 C ages resulted from averaging German oak and bristlecone pine ages.
Phenomena related to the natural carbon cycle as the 14 C distribution between atmosphere and ocean and the atmospheric response to the input of fossil fuel CO 2 and of 14 C produced in nuclear weapon tests have been quantitatively discussed by other authors using box models. However the exchange coefficients derived from the natural 14 C distribution do not agree with those valid to describe the short-term phenomena. A model consisting of a well mixed atmospheric box coupled to a long-term biosphere, of an ocean surface box and a diffusive deep ocean is discussed. The dynamic parameters were derived from the preindustrial 14 C distribution in atmosphere and ocean. A consistent description of phenomena with completely different characteristic times is possible, because in the box diffusion model the flux from mixed layer to deep sea increases for decreasing time constants of the perturbations. This is in contrary to box models where it is essentially independent of the time constants if they are smaller than a few hundred years. Due to this fact our model is valid for predictions of the atmospheric CO 2 response to the various possible future CO 2 input time functions. DOI: 10.1111/j.2153-3490.1975.tb01671.x
The following survey of carbon dioxide in nature places major emphasis on describing how the injection of CO2 into the atmosphere by man’s industrial activity has perturbed the natural carbon cycle on a global scale. In a sense, this injection is a mammoth geochemical experiment. It permits us to observe the transient response of the air, the oceans, and the biosphere to a major disturbance taking place over the interval of only a few years. Our quantitative understanding of the carbon cycle is thus repeatedly challenged and refined.
The availability of absolutely (dendrochronologically) dated German oak has allowed the Belfast laboratory to extend its published high-precision 14 C measurements of Irish oak (Pearson et al. 1986) by 2680 yr. The samples were selected at contiguous 20-yr intervals, following a precedent adopted and considered satisfactory in previous publications. All samples were measured for at least 200,000 counts within the 14 C channel. The statistical counting error, together with the error on standards, backgrounds and applied corrections, give a realistic precision quoted on each sample of ± 2.5‰ (± 20 yr). This error is considered high-precision for sample ages of 7000–8000 BP.
The high-precision radiocarbon calibration curve for short-lived samples (1–4 yr) of the early historical period (3rd millennium BC) presented previously (Vogel et al. 1986) has been further substantiated and extended to link with a similar curve produced by de Jong for part of the 4th millennium BC (de Jong & Mook 1980). The precise dendrochronological age of the sample set measured by de Jong has finally been fixed (de Jong, Mook & Becker 1989), so that the two sets now cover the period 1930–3900 BC, i.e., the Early Bronze Age and Late Chalcolithic periods of the Middle East. The standard calibration curve for the two sets is presented by Vogel and van der Plicht (1993).
Radiocarbon calibration data derived from German oak chronologies, ranging back to 7200 BC, have been published in the previous Calibration Issue (Stuiver & Kra 1986). In recent years, the German oak chronology has been extended to 7938 BC (Becker, this issue). For earlier intervals, tree-ring chronologies must be based on pine, because oak re-emigrated to central Europe at the Preboreal/Boreal transition, at about 8000 BC. We have established a 1784-yr pine chronology centered in the Preboreal, and have linked it tentatively to the absolutely dated oak master. We present here calibration data based on this link, for the age range, 7145–9439 BC.