Kychan N. Iron-nickel metal of ordinary chondrites as an indicator of the conditions of formation and evolution of meteorites parent bodies

The disssertation is devoted to the study of structure-mineralogical and chemical characteristics of genetically important minerals of iron nickel of the 2 carbonaceous xenoliths and 9 ordinary chondrites and to comparison them with the original and published data for other minerals of the chondrites. Distinctions between iron nickel grains of carbonaceous xenoliths and ordinary chondrites in size, structure and chemical composition are determined. Their sizes are on 1-2 orders lower than those of the ordinary chondrites matrix grains. Nickel iron aggregates in the carbonaceous xenoliths are mainly porous, xenomorphic, and contain many silicates inclusions. Nano- and micrometric metal grains of the carbonaceous xenoliths correspond with dust grains from the protoplanetary nebula in size. Their porous accretion structure indicates to a "soft" accretion because of low velocities of collision of dust grains in protoplanetary nebulae on the early stages of its evolution. On the base of iron nickel characteristics the studied ordinary chondrites were classified according to the degree of shock metamorphic transformation for iron nickel and are compared with the parameters of their shock changes previously established for silicate minerals of chondrite.