THE NEW CARBONACEOUS XENOLITH K4 AND ITS NATURE IN THE ORDINARY KRYMKA METEORITE (LL3.1)

Abstract

A study of the structural, mineralogical and chemical properties of another carbonaceous xenolith (K4) occurring in the Krymka chondrite (LL3.1) was made. The xenolith does not correspond to any known chemical sub-group of carbonaceous chondrites in terms of chemical composition and certain mineralogical characteristics, although its fine-grained component is similar to that of CI chondrites. Presence of graphite microcrystals makes the xenolith K4 similar to the Krymka xenoliths K1, K3, and Gr1-Gr7. Xenolith K4 has large amounts of iron sulfide. This may possibly be due to a nonuniform distribution of mineral fractions in a dusty component of the protoplanetary nebula, which could have both a local and more widespread character. During a pre-agglomeration period, K4 accumulated on its surface partially oxidized mineral dust in the same region of the gas-dust protoplanetary nebula as other xenoliths and chondrules of the Krymka meteorite. The evolution of xenolith K4 is generally similar to that of other Krymka graphite-bearing xenoliths, but differs in the relationship among minerals in the primary dusty aggregates. These features determined its distinct chemical and mineralogical characteristics and indicate mineralogical heterogeneity in the dusty component at the micro-level during the pre-accretional period of a mineral material development of the Solar system.