Novel dating method for speleothems with microscopic fluorescent annual layers.

Terrestrial carbonate deposits with a banded layer structure can be good tools for the extraction of past environmental information on global and local scales using trace element concentrations and stable isotope ratios. The absolute age dating is most important for the reconstruction of an environmental chronicle. The measurements of fluorescent annual bandings in stalagmites using a microscopic spectrofluorometer with an XY-stage can be a convenient dating method and are especially effective for young samples whose absolute age is very difficult to be determined by other methods. The number of annual bandings was objectively counted using a personal computer. The optimal conditions for the measurements are discussed. The annual banding in stalagmites is caused by the seasonal differences in the fulvic acid concentrations in the dripping water which forms speleothems.