Primordial noble cases from Earth's mantle: Identification of a primitive volatile component

Carbon dioxide well gases in Colorado, New Mexico, and South Australia show excesses of Xe124-128 correlated with I-129-derived Xe-129 and Ne-20/Ne-22 ratios that are higher than the atmospheric Ne-20/Ne-22 ratio. The xenon i sotopic data indicate the presence of a solarlike component deep within Ear th. The presence of this component in crustal and upper mantle reservoirs m ay be explained by a steady-state transport of noble gases from the Lower m antle, which still retains much of its juvenile volatile inventory. These m easurements also indicate that the mantle source of these noble gases in th e carbon dioxide well gases cannot be the source of Earth's present atmosph ere. The variations observed in Xe-129/Xe-130 between solar wind xenon, Ear th's atmosphere, and mantle samples may be generated by variations of iodin e/xenon in terrestrial reservoirs, as opposed to rapid early degassing.