THE WAY TO OVERCOME THE DIFFICULTY IN RE-OS DATING OF MOLYBDENITE

When a molybdenite was dissolved and treated by the conventional chemical procedure, it was difficult to achieve the isotopic equilibrium between the 187Os radiogenically accumulated in the molybdenite and “common” Os added as a kind of internal standard, even after chemically complete decomposition. It is evident that this isotopic disequilibrium effect results in deterioration of Re-Os age for the molybdenite. A newly developed analytical technique employing a microwave digestion was found out to promote the isotopic equilibration of Os from two sources and to provide us with the ages concordant with those obtained by other geochronometers. © 1990, The Japan Academy. All rights reserved.