Journal Highlights

Reading the rocks that reveal the history of impact events

Editor’s Highlight—

 

This paper considers the diffusion of heat and argon in a complex medium representing a polygenetic impact melt breccia. Using straightforward numerical methods, the authors explore a wide range of heating scenarios of target rocks that could represent surficial material of the Moon or any rocky planet which gives this approach broad applicability in planetary science. The numerical method is extremely versatile because specific properties (e.g., density, heat capacity, thermal conductivity, argon diffusivity) can be assigned to individual distance or volume elements in the numerical grid. Among the interesting results that emerge from this modeling study include the fact that differing fractional loses from feldspar and glass can arise from the contrast in temperature dependencies of argon diffusion in these two materials, and that these can cross over at high temperature from glass being less retentive to more retentive than feldspar. The broader conclusion is that re-heated materials can provide meaningful age information, and that the timing of multiple impacts might be preserved (and accessible to 40Ar/39Ar analysis) in polygenetic impact melt breccias.