Rare gas isotope contents and K-Ar ages of mineral concentrates from the Indarch meteorite

Abstract

The rare gas contents and isotopic abundances were measured for mineral separates from the enstatite chondrite Indarch. A cosmic ray exposure of 11 million years was estimated. There is an indication of a higher temperature during the time the meteorite was exposed to cosmic rays than during its preceding history. Different K-Ar ages were found for the different mineral concentrates ranging in age from 2.4 to 4.4 billion years. The Xe129/Xe132 ratio varies from 1.7 to 4.9 and is 2.1 for the troilite fraction in which one might expect I and Te; our conclusion is that either Xe was lost from troilite in its early history or the Xe129 is not associated in Indarch with I or Te.