Best practice methodology for 14C calibration of marine and mixed terrestrial/marine samples

Abstract

. (2015) Best practice methodology for 14C calibration of marine and mixed terrestrial/marine samples. Quaternary Geochronology, 27, pp. 164-171. Copyright © 2015 Elsevier B.V.A copy can be downloaded for personal non-commercial research or study, without prior permission or charge Content must not be changed in any way or reproduced in any format or medium without the formal permission of the copyright holder(s) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract: There is a lack of detailed guidance in the published literature on how to calibrate 14 C measurements made on marine or mixed marine/terrestrial (primarily human remains) samples. We describe what we consider to be the best approach towards achieving the most accurate calibrated age ranges, using the most appropriate ΔR and percentage marine diet estimates, and associated, realistic error terms on these values. However, this approach will increase the calibrated age range(s) by fully accounting for the variability in both the model and the material. While the discussion is based on examples from the UK and Iceland, the same fundamental arguments can be applied in any geographic location largely devoid of C 4 plants as the high δ AbstractThere is a lack of detailed guidance in the published literature on how to calibrate 14 C measurements made on marine or mixed marine/terrestrial (primarily human remains) samples. We describe what we consider to be the best approach towards achieving the most accurate calibrated age ranges, using the most appropriate ∆R and percentage marine diet estimates, and associated, realistic error terms on these values. However, this approach will increase the calibrated age range(s) by fully accounting for the variability in both the model and the material. While the discussion is based on examples from the UK and Iceland, the same fundamental arguments can be applied in any geographic location largely devoid of C 4 plants as the high δ 13C values from such plants can make identification of marine intake difficult to determine.

A Marine Reservoir Effect ∆R Value for Kitandach, in Prince Rupert Harbour, British Columbia, Canada

“…Following the ΔR calculation method of Cook et al (2015), we performed χ 2 tests on the samples to determine outliers and therefore potentially problematic contexts. Using samples that passed the test, we then calculated ΔR and error values for every possible terrestrial/marine pair for each viable context.…”

“…ΔR results from more pragmatic single-paired studies (e.g. Eldridge et al 2014) may vary simply because their smaller samples sizes are measured over longer periods of time without a robust test for statistical outliers (see Cook et al 2015).…”

“…This method uses all statistical information contained within contemporaneous multiple paired marine and terrestrial samples obtained from discrete contexts formed over short time periods (Ascough et al 2004(Ascough et al , 2005. Following the latest SUERC research (Cook et al 2015), the great advantage of taking multiple paired samples from a linked series of archaeological contexts is that the archaeological contexts and samples therein are not assumed to be coherent or correct, as outlying samples can be determined statistically using a simple chi-squared (χ 2 ) test of the marine and terrestrial data, before they are calibrated. The disadvantage of this approach is that even given ideal 14 C samples, the spatial-temporal range of suitable archaeological sites may be limited.…”

Stable Isotopes, Chronology, and Bayesian Models for the Viking Archaeology of North-East Iceland

“…δ 13 C values from these nine individuals were used to estimate the percentage amount of terrestrial and non-terrestrial protein, and thus degree of marine reservoir effect on the radiocarbon measurement. Standard linear interpolation methods were used (Cook et al 2015) to determine the percentage diet for each type, but the fact that dietary protein for most individuals was coming from terrestrial, marine, and freshwater systems made this methodology both cumbersome and unsatisfactory. Individuals with a high percentage of freshwater protein in their diet could not be 'corrected' for the FRE, given the data available at the time, and their dates could only be noted as providing a terminus post quem for their death (Table 1: Re-calibrated date).…”

Contemplating the history and future of radiocarbon dating in the American Southeast

“…We are not the first to offer such observations either on regional practices or with issues regarding radiocarbon as a whole (Bayliss 2009;Taylor 2000a;Wood 2015). In fact, we suggest that, in addition to this paper, readers should consult the following papers, as these are critical readings pertaining to the radiocarbon literature: Aitken (1990), Bayliss (2015), Bowman (1990), Buck and Meson (2015), Cook et al (2015), Guilderson et al (2005), and Taylor and BarYosef (2014).…”