Radiometric ages of selected Hawaiian corals

Abstract

A new scheme for the separation of uranium and thorium from one another and from other interfering ions, especially calcium, aluminum and iron was developed using mixed solvent systems and Biorad AG-l X8 resin. The complete separation takes place in one column operation after an initial precipitation procedure to reduce the ionic strength of the solution such that it will be soluble in the mixed solvent system. An automatic elution and fraction collector was developed to further facilitate the ion exchange separation. This allows the entire separation to take place without operator attention after the initial set up. The elution system automatically changes elution reservoirs and controls the liquid level above the resin bed. The fraction collector allows collection in constant time, constant volume and constant number of drops modes and is especially convenient for ion exchange column developmental work. In the constant volume mode, provision is made to collect each elution fraction separately and with an absolute minimum of cross contamination. These systems were applied to the separation of uranium and thorium from corals from the island of Oahu, Hawaii. Computer programs were developed to load the alpha spectrometric data of these analyses as outputed on Teletype 8 level ascii code into a computer, plot a graph of the data, total the counts under each peak, and calculate the age of the sample. These resultant ages are discussed as to geologic implication.