The trace element composition of the Onello meteorite is analyzed in detail using SEM and LA-ICP-MS. The following Ni contents of minerals are determined (wt %): 23.0-25.4 in taenite, 5.8-8.8 in kamacite, 22-26 in schreibersite, 44-52 in nickelphosphide, 20.6-21.8 in allabogdanite, and 75-81 in awaruite. In the trace element content, the Onello meteorite corresponds to the IAB group of iron meteorites. Inside this group, it mostly matches the sHH subgroup (with high Au and Ni contents). The presence of allabogdanite in the meteorite indicates the high PT parameters of its formation: >8 GPa and 1000-1400 °C. Thus, the formation of the Onello meteorite is related to impact metamorphism of a parental body of iron meteorites of the IAB group and vinonaites, in which a P- and Ni-rich area underwent melting and further crystallization.
A representative collection (138 analyses) of chromites from kimberlites of the Botuobinskaya pipe in Yakutia was studied. With allowance for the Cr, Ti, and Al contents, the chromites are subdivided into the low Cr aluminous group A and the high Cr and high Ti group B. The chromites of group A with their compositional variations controlled by the Al 3+ -Cr 3+ isomorphism are not related to kimberlite in compo sition and reveal attributes of restites. The chromites of group B with heterovalent Ti 4+ + Fe 2+ + Fe 3+ -3Cr 3+ isomorphism vary in their composition in line with the compositional variations of kimberlites, thus demon strating their primary magmatic origin. The chromites of the second group crystallized simultaneously with olivines from kimberlites, and both minerals could have formed nodules of spinel dunite.
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