Planetary-type rare gases in an upper mantle-derived amphibole

All 23 stable rare gas isotopes in a mantle-derived aluminous Ti-rich amphibole, kaersutite, were measured, and the abundance pattern indicated by the results is similar to the 'planetary' rare gas pattern of carbonaceous chondrites. The He-3/He-4 ratio of (4.9 + or - 0.6) times 10 to the -5th power is anomalously high. Ne-21 is enriched relative to the abundance of the other two neon isotopes in the atmosphere, while the heavy isotopes of Kr and the Xe isotopes are within error of the atmospheric values. The analytical procedure is described. It is concluded that part of the primordial rare gases of the earth are still present in some parts of the upper mantle and that these gases retain a faithful record of the 'planetary' primordial rare gas elemental signature.