• Centuries of Marine Radiocarbon Reservoir Age Variation within Archaeological Mesodesma donacium Shells from Southern Peru

      Jones, Kevin B.; Hodgins, Gregory W. L.; Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Sandweiss, Daniel H. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Mollusk shells provide brief (5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (~2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 +/- 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 +/- 60 to 730 +/- 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty.