Mg de cristallisation des chondres et leurs compositions minéralogiques et chimiques

Previous studies suggested the existence of a correlation between 26 Al relative crystallisation ages and mineralogical and bulk chemical compositions of ferromagnesian chondrules from the Bishunpur and Semarkona unequilibrated ordinary (Mostefaoui et al., 2002; Tachibana et al., 2003). However, because the precision in 26 Al ages was moderate, these correlations are questionable. Here, we report mineralogical and chemical compositions of 14 ferromagnesian chondrules from Semarkona for which precise 26 Al ages were previously obtained (Villeneuve et al., 2009). We find global correlation of 26 Al ages neither with bulk chemical composition of chondrules nor with the different types of ferromagnesian chondrules, i.e. PO, POP and PP. This indicates that if some kind of correlations between chemical compositions of chondrules and their ages of formation exist, they do not exist at timescales that can be measured with the 26 Al26 Mg systematics but presumably at much shorter timescales.