ORIGIN OF NOBLE GASES IN THE TERRESTRIAL PLANETS

Abstract

Identifying the mechanisms that drove the evolution of planetary volatiles from primordial to present-day compositions is one of the classic challenges in the planetary sciences. The field bristles with models of one type or another, but none are without difficulties. Efforts to understand the histories of volatile species in the atmospheres and interiors of the terrestrial planets have concentrated on their noble gases, free of the entanglements of chemical interaction, as evolutionary tracers. The elemental and isotopic compositions of these minor constituents are rich in clues to the chemical characteristics of their source reservoirs, the physics of their evolution, and...