ISOLATION OF URANIUM AND THORIUM FROM PURE CARBONATE SPELEOTHEMS FOR URANIUM SERIES AGE-DETERMINATION

A refined chemical procedure for the isolation of uranium and thorium from pure carbonate speleothems was developed. Almost quantitative recoveries of both elements could be achieved by performing anion exchange separation of uranium from the sample solution prior to the co-precipitation of thorium with iron hydroxide. The separation efficiency was tested both with calcium carbonate and real carbonate speleothem samples after addition of chemical standards of uranium and thorium. Chemical recoveries of uranium and thorium were determined by ICP-AES. The applicability of the procedure for the uranium series dating of speleothems is demonstrated for two cave localities.