NITROGEN ISOTOPE ANOMALIES IN PRIMITIVE ORDINARY CHONDRITES

Large anomalies in nitrogen isotopic composition were found in two type L3 ordinary chondrites. One of them is isotopically heavy, and the other is isotopically light. The carriers of anomalous nitrogen are partly soluble in HCl. Thus, the anomalies are probably due to new types of presolar grains, although they have not been identified yet. Trapped Ar-36 in these chondrites seems to be associated with this anomalous nitrogen, and may be presolar in origin. The presence of two different nitrogen isotopic anomalies suggests that the parent body of L chondrites and also the primitive solar nebula were not homogeneous. Nitrogen isotope anomalies seem to be useful in detecting subdivisions of chemical groups of chondrites.