14C dating on marine bio-constructions from a submarine cave in the Adriatic Sea

A new type of “speleothem” was recently found and described in submarine caves along the Southern coast of the Adriatic Sea in Italy. Previous studies demonstrated the fully biogenic and submarine origin of these structures which appeared to be formed by calcareous tubules of worms, embedded in a much finer texture matrix. AMS radiocarbon dating analyses allowed the determination of the age of these structures and to study the temporal evolution of their growth rate. In this paper, we report new dates obtained on the matrix around the already dated core tubules. Compositional analyses demonstrated that the matrix is mainly formed by calcium carbonate and AMS radiocarbon age measurements performed at CEDAD suggest its biogenic origin. Absolute ages on the matrix are statistically consistent internally and with the calcareous tubules. The obtained results are highly complementary to other studies being performed in order to identify the biological processes governing the formation and growth of these structures.