Olivines in angrite LEW 87051: Phenos or xenos

Abstract

Nyquist et al. recently reported the presence of live Mn-53 in angrite LEW 86010 when it crystallized. Hence, melting must have occurred within approx. 10 Ma of the accretion of the angrite parent body, and LEW 86010 is the oldest known differentiated meteorite. This discovery has made it even more desirable to understand teh petrogenesis of angrites, which presumably were all formed at a similar time. As part of the continuing work on angrite petrogenesis, crystallization experiments were conducted on LEW 87051, the other Antarctic angrite, to clarify its petrogenesis. Several aspects of the experimental work is reported. Although the details are not understood, it is clear that the Cr abundance in the experimental olivines must be controlled by spinel crystallization