The role of post-shock heating by plastic deformation during impact devolatilization of calcite

TL;DR

This study investigates how post-shock heating from plastic deformation during impacts influences devolatilization in calcite, revealing its significance in understanding meteorite thermal metamorphism and impact conditions in the early Solar System.

Contribution

It demonstrates that impact simulations incorporating post-shock heating align with laboratory results, highlighting the importance of plastic deformation in shock-induced devolatilization.

Findings

iSALE simulations match calcite devolatilization experiments

Post-shock heating significantly affects CO2 release

Reassessment needed for meteorite thermal metamorphism interpretations

Abstract

An accurate understanding of the relationship between the impact conditions and the degree of shock-induced thermal metamorphism in meteorites allows the impact environment in the early Solar System to be understood. A recent hydrocode has revealed that impact heating is much higher than previously thought. This is because plastic deformation of the shocked rocks causes further heating during decompression, which is termed post-shock heating. Here we compare impact simulations with laboratory experiments on the impact devolatilization of calcite to investigate whether the post-shock heating is also significant in natural samples. We calculated the mass of CO$_2$ produced from the calcite, based on thermodynamics. We found that iSALE can reproduce the devolatilization behavior for rocks with the strength of calcite. In contrast, the calculated masses of CO2 at lower rock strengths are systematically smaller than the experimental values. Our results require a reassessment of the interpretation of thermal metamorphism in meteorites.