The Okhansk Meteorite: Specifics of Composition, Structure, and Genesis

A.I. Bakhtin^*, G.V. Sonin^**, R.Kh. Sungatullin^***, R.D. Petrova^****

Kazan Federal University, Kazan, 420008 Russia

E-mail: ^*Anatoly.Bakhtin@kpfu.ru, ^**g_sonin@mail.ru, ^***rafael.sungatullin@kpfu.ru, ^****Rimma.Petrova@kpfu.ru

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Abstract

The Okhansk meteorite fell on August 18, 1887 near the village of Tabor, about 15 km away from the town of Okhansk in Perm province and weighed 186.5 kg (the total weight of collected fragments, according to P.I. Krotov, was more than 245 kg). The shock wave from the meteorite entry knocked down animals and riders on horses. Despite the fact that it was significantly stronger than that caused by the Chelyabinsk meteorite of 2013, all information about this meteorite has completely erased from people's memory. It has been shown that the meteorite is an ordinary olivine-bronzite chondrite. Its main silicate minerals are olivine, bronzite, plagioclase, and diopside. The main ore minerals are kamacite and troilite. The meteorite contains silicate glass in large amounts. The analysis of the composition and structure of the Okhansk meteorite has demonstrated that it was formed at the early stages of accretion of the melted substance of the protosolar nebula without undergoing endogenous, temperature, or pressure changes.

Keywords: Okhansk meteorite, chondrites, protosolar nebula, genesis

Figure Captions

Fig. 1. Orthopyroxene-olivine chondrule. ОРх in the center, Ol in the periphery. Black color – ore minerals.

Fig. 2. Dark-gray silicate glass in the center of the olivine chondrule.

Fig. 3a. Olivine-orthopyroxene chondrule in the olivine-orthopyroxene-plagioclase chondrule (chondrule in chondrule). Single nicol.

Fig. 3b. The same in crossed nicols.

Fig. 4. Olivine chondrule (in the center). The plagioclase chondrule with olivine inclusions on the left. Nicols +.

Fig. 5. Accretion of two granular olivine chondrules. The orthopyroxene chondrule adjoins from the above. Black color – ore minerals.

Fig. 6. Radial orthopyroxene chondrule. Single nicol.

Fig. 7. The chondrule consisting of silicate glass with pyroxene microlites and fine-grained albite residual cells. Single nicol.

Fig. 8. Kamacite Km (white) and troilite Tr (pink) releases in the matrix.

Fig. 9. Olivine-pyroxene-plagioclase chondrule (analysis 7.1 in Table 4, 5).

References

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For citation: Bakhtin A.I., Sonin G.V., Sungatullin R.Kh., Petrova R.D. The Okhansk meteorite: Specifics of composition, structure, and genesis. Uchenye Zapiski Kazanskogo Universiteta. Seriya Estestvennye Nauki, 2016, vol. 158, no. 4, pp. 569–582. (In Russian)

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