An analysis of radiocarbon assays produced by three laboratories: a case study on the Croxton site, locality J, northern Alaska

Abstract

Radiocarbon assays produced by three different laboratories are compared to examine potential discrepancies among them: Dicarb Radioisotope Co., Geochron Laboratories, and Beta Analytic, Inc. A semi-formal assumption that radiometric assays produced by Dicarb are "too young" when compared to those produced by other laboratories is statistically tested. Radiometric assays and accelerator mass spectrometry (AMS) dates produced from materials excavated at the Croxton site, Locality J, Tukuto Lake, Northern Alaska, will be used as the primary data set within this research. Statistical analyses demonstrate that radiocarbon assays produced by Dicarb tend to be "younger" when compared to those produced by other laboratories on crosscheck samples. In addition, an unsystematic pattern is exhibited among the discrepancies between Dicarb and crosscheck assays. Radiocarbon assays are calibrated using the CALIB rev4.3 program in order to assess statistical overlap among the dates (Stuiver and Reimer 1993b; Stuiver et al. 1998a, 1998b). Radiocarbon assays produced by Beta Analytic and Geochron on materials recovered from the Croxton site, Locality J, support both "traditional" and "alternative" cultural-historical frameworks constructed for North Alaskan prehistory (Anderson 1978, 1984; Dumond 1980, 1984; Gerlach and Hall 1988; Gerlach 1989; Gerlach and Mason 1992; Mason and Gerlach 1995).