No Systematic Early Bias to Mediterranean¹⁴C Ages: Radiocarbon Measurements from Tree-Ring and Air Samples Provide Tight Limits to Age Offsets

Abstract

ABSTRACT. Existing data and theory do not support a recent assertion that upwelling of old carbon has led to systematically 100-300 yr too old radiocarbon ages for the Mediterranean region. Similarly, the prehistoric tree-ring record produced over 3 decades by the Aegean Dendrochronology Project is shown to provide robust, well-replicated data, contrary to a recent unfounded assertion. 14 C and dendrochronology provide an accurate and precise chronometric framework for the Mediterranean region.

Radiocarbon Dating Archaeological Samples in the Eastern Mediterranean, 1730 to 1480 Bc: Further Exploring the Atmospheric Radiocarbon Calibration Record and the Archaeological Implications*

“…2006) with the IntCal09 record as shown in Figure 11 for the 1720s bc through to the 1660s bc . These data demonstrate that there is no significant regional offset, even close to the Aegean Sea—and thus they also disprove the relevance for this time interval of claims of upwelling in the Mediterranean as supposedly causing a substantive radiocarbon offset in terrestrial (e.g., archaeological) samples (thus contra Keenan 2002—see previously Manning et al . 2002; and for further comprehensive evidence to the contrary, now see Bronk Ramsey et al .…”

“…11) further indicates no substantive regional offset (e.g., depletion) in eastern Mediterranean 14 C ages 1730 to 1480 bc; 2 as does the good match over seven decades between the oak tree-ring sample from Miletos (coastal western Turkey: data from Bronk Manning et al 2006) with the IntCal09 record as shown in Figure 11 for the 1720s bc through to the 1660s bc. These data demonstrate that there is no significant regional offset, even close to the Aegean Sea-and thus they also disprove the relevance for this time interval of claims of upwelling in the Mediterranean as supposedly causing a substantive radiocarbon offset in terrestrial (e.g., archaeological) samples (thus contra Keenan 2002-see previously Manning et al 2002; and for further comprehensive evidence to the contrary, now see Bronk .…”

Radiocarbon in Annual Tree Rings from Thailand During the Pre-Bomb Period, Ad 1938–1954

“…The new results (OZD108U2 and OZD109U2; Table 1) differ significantly from those of the first set (-48.5 ± 5.7‰ and -40.8 ± 5.5‰ for 1953 and1954, respectively;Hua et al 2000), and show no strong depletion. Given the absence of strong upwelling for the extended period 1938 to 1951 and a subsequent critical evaluation of the concept and likely extent of possible old CO 2 effects downwind of oceanic upwelling localities (Manning et al 2002), the repeat measurements of the 1953 and 1954 Pinus kesiya rings are preferably accepted. Possible reasons for the divergence in the first set of measurements include accidental contamination in the pretreatment and target preparation, and the result of some instability in the measurement system and the accelerator.…”

Intcal04 Terrestrial Radiocarbon Age Calibration, 0–26 Cal Kyr BP

“…These regional offsets were neglected, with the exception of 14 C measurements of an Alaskan tree which were normalized to the Pacific Northwest trees by adding the average offset of 14 ± 3 yr as reported in Stuiver et al (1998a). Regional offsets may also result from growing season differences, altitudinal effects, or proximity to areas of intense ocean upwelling, melting permafrost, or volcanic emissions, and are potentially significant for certain localities and time periods (Damon et al 1996;Dellinger et al 2003;Kromer et al 2001;Manning et al 2001;Sakamoto et al 2003). The time-varying nature of such signals, even if they can be detected, precludes an easy correction in the calibration process (Manning et al 2002).…”