AN ACID-ETCH STUDY OF THE KAPOETA ACHONDRITE - IMPLICATIONS FOR THE ARGON-36 ARGON-38 RATIO IN THE SOLAR-WIND/

Noble gases were measured in the Kapoeta achondrite by means of step-w ise closed-system acid-etching with H2SO3. Isotopic ratios indicate th at He, Ne and Ar are primarily solar in origin, although elemental abu ndance ratios indicate that the He and Ne have been significantly depl eted relative to the Ar. Xenon is dominated by a typical trapped meteo ritic component, and the same is probably true for Kr. The initial 11% of the Ar released from the sample by acid etching has a cumulative A r-36/Ar-38 ratio of 5.58 +/- 0.03, which indicates that the solar wind at some time in the past had a Ar-36/Ar-38 ratio significantly above previous values suggested for this ratio.