Original paper

Na behaviour in shock-induced melt phase of the Yanzhuang (H6) chondrite

Ming, Chen; Xiande, Xie

European Journal of Mineralogy Volume 8 Number 2 (1996), p. 325 - 334

19 references

published: Apr 26, 1996
manuscript accepted: Oct 26, 1995
manuscript received: Dec 1, 1994

DOI: 10.1127/ejm/8/2/0325

BibTeX file

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Abstract The Yanzhuang meteorite was severely shocked and reheated in an extraterrestrial impact event; it consists of four shock fades 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°C/s). Na redistribution in the melt phase is shown here: (1) Na concentrated to Fe-Ni-S melt at high pressure and high temperature. Fe-Mn-Na phosphate, a possibly new phase, was formed in the metal-troilite eutectic nodules. (2) Minor amounts of Na were solidified into the recrystallized low-Ca pyroxene, thus resulting in a slightly enhanced Na content in the pyroxene. (3) Part of the Na was "frozen" into the silicate melt glass


Na-behaviourshock faciesmelt phaseYanzhuang chondrite