Comment on “Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals” by R.G. Fairbanks et al. (Quaternary Science Reviews 24 (2005) 1781–1796)☆☆doi of original article: 10.1016/j.quascirev.2005.04.007 and “Extending the radiocarbon calibration beyond 26,000 years before present using fossil corals” by T.-C. Chiu et al. (Quaternary Science Reviews 24 (2005) 1797–1808)☆☆☆☆doi of original article: 10.1016/j.quascirev.2005.04.002

Abstract

A recently published radiocarbon calibration curve extending to 50,000 cal BP ) is purportedly superior to that generated by the IntCal working group beyond the end of the tree-ring data at 12,400 cal BP ). This claim is based, in part, on different diagenetic screening criteria and pretreatment for coral samples Chiu et al. 2005) which do not stand up under careful scrutiny. Also at issue is the conversion of the coral-based calibration curve to an atmospheric curve where large inter-annual variability in the sea-surface age reservoir age has been observed in the southwest Pacific where one of two sets of corals used were sampled. In addition we comment on the seemingly ad hoc statistical methods utilized by Fairbanks et al. (2005) to construct their curve. We recognize the value of the Fairbanks et al. (2005) coral radiocarbon data set, but reassert the need for multiple, independently derived data to provide confirmation and validation to all radiocarbon calibration data. This is especially important before 26,000 cal BP when lower sea-levels of the last glacial maximum exposed most coral samples to alteration by fresh water

14C‐dated fluctuations of the western flank of the Scandinavian Ice Sheet 45–25 kyr BP compared with Bølling–Younger Dryas fluctuations and Dansgaard–Oeschger events in Greenland

“…Conversion of 14 C years to calendar years is still uncertain for old samples (van der Plicht et al 2004; Reimer et al 2006; Skinner 2008; Weninger & Jöris 2008). In Fig.…”

Sea surface temperatures from oxygen isotopes in marine molluscs in Middle and Later Stone Age sites, South Africa

“…Arguably, powder XRD (pXRD) is a more precise and accurate analytical technique for detecting calcite contamination, as detection and quantification limits for calcite can be as low as 0.2% and 1% respectively (Reimer et al, 2006). However, the instrumentation is expensive and not readily available in most archaeological science laboratories.…”

Moderate rates of late Quaternary slip along the northwestern margin of the Basin and Range Province, Surprise Valley fault, northeastern California

“…Calibration of radiocarbon ages is controversial beyond 26,000 cal year B.P. [ Reimer et al , 2006], but a calibration curve based on uranium series dating of fossil corals [ Fairbanks et al , 2005] yields a tentative 2 σ calibrated age of about 27,800 ± 730 cal year B.P. for deposition of the Trego Hot Springs tephra.…”