INVESTIGATIONS OF THE POTASSIUM-ARGON METHOD OF AGE DETERMINATION USING SOLID ISOTOPIC DILUTION AND GAS REMOVAL BY CRUSHING

Preliminary work on a new technique of isotopic dilution analysis useful in the measurement of radiogenic Ar content of rocks or mineral samples in age determination is reported. Argon-38 is added to the sampies as the diluting isotope dissolved in a solid glassy silicate which approximates the pertinent properties of the sample. Crushing as well as melting can be used to extract the representative portion of gas needed to apply the isotopic dilution method. In the preliminary investigations orderof-magnitude agreement was obtained with the Ar content of samples determined by conventional technlques. The possibilities of the method include elimination of uncertainties about complete extraction of Ar from samples, use of radioactive counting of argon-39 as a determinative technique, and preferential removai of air contamination by crushing to enabie extension of the K-Ar method to Younger ages. (auth