Rare gas systematics in popping rock:: Isotopic and elemental compositions in the upper mantle

New experimental data on the isotopic variations of neon, argon, and xenon in a popping rock imply that the Ar-40/Ar-36 ratio of the upper mantle is less than 44,000 and that the Xe-129/Xe-130 ratio is less than 8.2. The elemental abundance pattern of rare gases is chondritic-like and is quite distinct from the solar pattern. These data imply that Earth accreted from planetesimals that probably underwent a transformation of their rare gas budget from solar- to chondritic-like, leaving the isotopic composition unchanged from the solar pattern.