Figure 1

Origin of atmospheric Xe’s precursor (U-Xe). (a) AVerage Carbonaceous Chondrite Xe (AVCC-Xe)¹¹, solar wind xenon (SW³²) and U-Xe¹¹ signatures mass-dependently fractionated to the extent where their ¹²⁶Xe/¹³⁰Xe matches the Air-Xe value. Initial U-Xe composition is shown by dotted line. It appears that post-MDF AVCC-Xe and SW-Xe compositions contribute more ¹³⁶Xe relative to ¹³⁰Xe than the atmosphere actually contains, therefore excluding chondritic and solar components as the only sources of atmospheric volatiles¹¹. The mass-dependently fractionated signature of U-Xe exhibits deficits in ¹²⁹Xe and ^131–134Xe that correspond to latter additions of radiogenic and fissiogenic contributions from ¹²⁹I and ²⁴⁴Pu, respectively¹¹. (b) Mixing diagram between cometary and Q³³/SW-Xe³² components to account for the origin of U-Xe in the terrestrial atmosphere (modified from¹²), as modelled by the thick arrow. Subsequent evolution from U-Xe to Air by MDF is represented by the solid curve. (c) Comparison of the abundance patterns of noble gases in the Sun, in volatile-rich primitive chondrites and in the atmospheres of Earth and Mars (modified after^17,18). Earth and Mars are depleted in xenon relative to krypton and meteorites, with Kr/Xe close to the solar abundance.