SURMOUNTING THE PROBLEMS OF RADIOMETRIC DATING IN THE SUBMERGED CAVES OF THE YUCATAN: THE LA MINA AND HOYO NEGRO EXAMPLES (Invited Presentation)
We have been able to surmount, or at least limit these problems in studies of the deep natural trap of Hoyo Negro and the ochre mines of upper tunnels in coastal Quintana Roo using a variety of approaches. In the ochre mines, we established associated charcoal as artifacts and likely produced by human activity 12.0-10.2 ka by identifying burned tree species and distinguishing them from forest fire charcoal found in Hoyo Negro. At Hoyo Negro itself, with its rich fauna and complex depositional setting, we combined 14C dating of bioapatites as terminus post quem and overlying charcoal, guano, or calcite as terminus ante quem, findings backed up by the chronology of postglacial sea-level rise. Animal fossils date between 43 and 10 ka. Comparison of bone apatite ages with actual ages based on organic 14C or U-Th calcite ages in three unusual cases (bat bones from guano, bone and charcoal from an isolated overhung ledge, flowstone on a complete skeleton) demonstrated a consistent ~3.2 ka offset between the two. This has enhanced confidence in the ~12.9 ka enamel-age of “Naia” the young woman from this site, verifying her as early Paleoindian in age.