Bimini update Gene Shinn has kindly directed us to a Nature article from 1980 with some more explanation of the geological work done there, including a set of C-14 dates (all fairly internally consistent). Probably subscription-only; here's the reference:
Marshall McKusick & Eugene A. Shinn, Bahamian Atlantis reconsidered, Nature 287, 11 - 12 (04 September 1980).