非表示:
キーワード:
AMS, Bone pretreatment, Intercomparison, Radiocarbon, Ultrafiltration
要旨:
A quality control program was undertaken to test the merit of different techniques for the preparation of Late Pleistocene bone at the A.E. Lalonde AMS Laboratory in Ottawa (Canada). The samples studied here include a mammoth bone (S-EVA 2000) previously dated by other labs (Oxford, Kiel, Mannheim) with results ranging between 35,280 and 31,660 14C yr BP (n = 10), a bison bone (S-EVA 2001) previously dated between 47,300 and 40,200 14C yr BP (n = 9; Talamo and Richards, 2011), and our in-house background standard (Hollis Mine Mammoth, HMM). Samples were prepared in four different ways: (1) no ultrafiltration and combustion by elemental analyser (EA); (2) ultrafiltration and EA combustion; (3) no ultrafiltration and quartz tube combustion; (4) ultrafiltration and quartz tube combustion. All four methods produced dates for the S-EVA 2000 bone between 34,530 and 34,080 14C yr BP (n = 7) and consistent stable isotope data (δ13C, δ15N, C:N). Results for the HMM bone ranged from 54,600 to 46,800 14C yr BP. Further, the S-EVA 2001 was prepared without ultrafiltration and combusted on the EA, resulting in a date of 45,010 ± 460 14C yr BP. Finally, since a major challenge with dating Late Pleistocene bone is to decipher between finite and infinite ages, we report results from two years of measurement of the HMM bone, which is prepared with each bone batch. The average age of the HMM is 50,700 ± 3400 14C yr BP (n = 17) when not ultrafiltered, and 48,400 ± 2900 14C yr BP (n = 13) when ultrafiltered. Results from this study do not reinforce or negate the use of ultrafiltration, but it was determined that combustion by EA is preferred as it gives %C and %N values.
