COMPARING DIRECT CARBONATE AND STANDARD GRAPHITE 14C DETERMINATIONS OF BIOGENIC CARBONATES. Issue 2 (19th April 2021)

• Record Type: Journal Article
• Authors: Bright, Jordon; Ebert, Chris; Kosnik, Matthew A; Southon, John R; Whitacre, Katherine; Albano, Paolo G; Flores, Carola; Frazer, Thomas K; Hua, Quan; Kowalewski, Michal; Martinelli, Julieta C; Oakley, David; Parker, Wesley G; Retelle, Michael; do Nascimento Ritter, Matias; Rivadeneira, Marcelo M; Scarponi, Daniele; Yanes, Yurena; Zuschin, Martin; Kaufman, Darrell S
• Is Part Of: Radiocarbon. Volume 63:Issue 2(2021)
• Page Start: 387
• Page End: 403
• Publication Date: 2021-04-19
• Subjects: biogenic carbonate, -- direct carbonate 14C AMS, -- standard graphite 14C AMS; Radiocarbon dating -- Periodicals; 930.1028505
• DOI: 10.1017/RDC.2020.131
• Languages: English
• ISSNs: 0033-8222

Abstract

ABSTRACT: The direct carbonate procedure for accelerator mass spectrometry radiocarbon (AMS 14 C) dating of submilligram samples of biogenic carbonate without graphitization is becoming widely used in a variety of studies. We compare the results of 153 paired direct carbonate and standard graphite 14 C determinations on single specimens of an assortment of biogenic carbonates. A reduced major axis regression shows a strong relationship between direct carbonate and graphite percent Modern Carbon (pMC) values (m = 0.996; 95% CI [0.991–1.001]). An analysis of differences and a 95% confidence interval on pMC values reveals that there is no significant difference between direct carbonate and graphite pMC values for 76% of analyzed specimens, although variation in direct carbonate pMC is underestimated. The difference between the two methods is typically within 2 pMC, with 61% of direct carbonate pMC measurements being higher than their paired graphite counterpart. Of the 36 specimens that did yield significant differences, all but three missed the 95% significance threshold by 1.2 pMC or less. These results show that direct carbonate 14 C dating of biogenic carbonates is a cost-effective and efficient complement to standard graphite 14 C dating.