THE NEW ZEALAND KAURI (AGATHIS AUSTRALIS) RESEARCH PROJECT: A RADIOCARBON DATING INTERCOMPARISON OF YOUNGER DRYAS WOOD AND IMPLICATIONS FOR INTCAL13

We describe here the New Zealand kauri (Agathis australis) Younger Dryas (YD) research project, which aims to undertake Delta C-14 analysis of similar to 140 decadal floating wood samples spanning the time interval similar to 13.1-11.7 kyr cal BP. We report C-14 intercomparison measurements being undertaken by the carbon dating laboratories at University of Waikato (Wk), University of California at Irvine (UCI), and University of Oxford (OxA). The Wk, UCI, and OxA laboratories show very good agreement with an interlaboratory comparison of 12 successive decadal kauri samples (average offsets from consensus values of -7 to +4 C-14 yr). A University of Waikato/University of Heidelberg (HD) intercomparison involving measurement of the YD-age Swiss larch tree Ollon505, shows a HD/Wk offset of similar to 10-20 C-14 yr (HD younger), and strong evidence that the positioning of the Ollon505 series is incorrect, with a recommendation that the C-14 analyses be removed from the IntCal calibration database.