NA BEHAVIOUR IN SHOCK-INDUCED MELT PHASE OF THE YANZHUANG (H6) CHONDRITE

Abstract

The Yanzhuang meteorite was severely shocked and reheated in an extraterrestrial impact event; it consists of four shock facies characteristic of disequilibrium shock effects. This study reveals that the volatile element Na in the shock-induced melt phase is not unequivocally depleted. Na preservation in the melt phase could correspond to: (1) high shock pressures (>=30 GPa) and high post-shock temperatures that acted in most parts of the meteorite, resulting in reduced rock porosity and lower pressure and temperature gradients between the melt phase and the surrounding shock facies. (2) quenching of melt phase (6 - 400 deg C/s).