Effects of friction and plastic deformation in shock-comminuted damaged rocks on impact heating

TL;DR

This study uses shock-physics simulations to show that friction and plastic deformation significantly increase impact heating in rocks during hypervelocity impacts, especially at lower velocities, broadening the conditions for impact-induced melting and aging resets.

Contribution

It introduces a new understanding of how friction and plastic deformation affect impact heating, revealing a wider range of impact velocities that can cause significant heating in planetary rocks.

Findings

Impact heating is enhanced during pressure release in strength-bearing rocks.

Lower impact velocities can produce melting and argon loss due to additional heating.

The range of impact conditions causing impact heating is broader than previously believed.

Abstract

Hypervelocity impacts cause significant heating of planetary bodies. Such events are recorded by a reset of 40Ar-36Ar ages and/or impact melts. Here, we investigate the influence of friction and plastic deformation in shock-generated comminuted rocks on the degree of impact heating using the iSALE shock-physics code. We demonstrate that conversion from kinetic to internal energy in the targets with strength occurs during pressure release, and additional heating becomes significant for low-velocity impacts (<10 km/s). This additional heat reduces the impact-velocity thresholds required to heat the targets with the 0.1 projectile mass to temperatures for the onset of Ar loss and melting from 8 and 10 km/s, respectively, for strengthless rocks to 2 and 6 km/s for typical rocks. Our results suggest that the impact conditions required to produce the unique features caused by impact heating span a much wider range than previously thought.