Primordial noble gases from Earth's mantle: identification of a primitive volatile component
Carbon dioxide well gases in Colorado, New Mexico, and South Australia show excesses of (124-128)Xe correlated with (129)I-derived (129)Xe and (20)Ne/(22)Ne ratios that are higher than the atmospheric (20)Ne/(22)Ne ratio. The xenon isotopic data indicate the presence of a solarlike component deep within Earth. The presence of this component in crustal and upper mantle reservoirs may be explained by a steady-state transport of noble gases from the lower mantle, which still retains much of its juvenile volatile inventory. These measurements also indicate that the mantle source of these noble gases in the carbon dioxide well gases cannot be the source of Earth's present atmosphere. The variations observed in (129)Xe/(130)Xe between solar wind xenon, Earth's atmosphere, and mantle samples may be generated by variations of iodine/xenon in terrestrial reservoirs, as opposed to rapid early degassing.
Caffee
MW
Lawrence Livermore National Laboratory, Post Office Box 808, Livermore, CA 94550, USA. Department of Geology, Arizona State University, Tempe, AZ 85287, USA. Department of Geology and Geophysics, University of Minnesota, Minneapol.
Hudson
GB
Velsko
C
Huss
GR
Alexander
EC
Chivas
AR