GEOKHI revealed the secret of the formation of iron-stone pallasites — anti-crystals helped
Russian scientists from the Institute of Geochemistry and Analytical Chemistry named after. IN AND. Vernadsky RAS (GEOKHI) together with colleagues from the Institute of Geology and Mineralogy named after. V. S. Sobolev SB RAS and the Faculty of Geology of Moscow State University. M.V. Lomonosov. They examined grains of olivine — crystals from the iron-stone meteorite-pallasite Seymchan, found in 1967 in the Magadan region, and they discovered the secret of the origin of celestial bodies of this type. The results were published in the journal Geochemistry International.
Pallasite. Photo: kamnisneba.ru
Pallasite meteorites are contemporaries of the formation of the planets of the Solar System. They belong to the class of stony-iron meteorites and consist of olivine crystals enclosed in a mass of nickel iron. Until recently, scientists did not have a consensus on their education.
The research at the Laboratory of Meteoritics and Cosmochemistry of the Geochemical Institute of the Russian Academy of Sciences began with the fact that the staff became interested in the nature of the formation of the so-called anticrystals discovered in the Seymchan meteorite, which is stored in the meteorite collection of the Russian Academy of Sciences.
Anticrystals (crystal-shaped voids) are found in olivine crystals and contain grains of nearly pure metallic iron. It is curious that scientists have been paying attention to these voids in olivines of various pallasites since the middle of the 20th century, in particular, Vladimir Ivanovich Vernadsky himself made a report about them, calling them “capillaries.” However, the lack of the necessary observational equipment and experimental data did not allow us to understand the nature of these “capillaries.” Modern research methods have led scientists to the conclusion that anti-crystals are nothing more than traces of multi-stage processes in the formation of meteorite matter.
In particular, it was hypothesized that voids are formed due to the accumulation of defects in the crystal lattice of olivines as a result of mechanical influences: compression, tension and chemical reactions between olivine and surrounding iron. This was confirmed when comparing calculations and observations with the results of experiments on olivines from terrestrial rocks.
The presence of such voids in pallasite olivines also led scientists to the conclusion that nickel iron and olivine, which are part of pallasites, were originally belonged to the metallic core and silicate mantle of the parent body and were mixed with each other, reacted as a result of a catastrophic event, probably a collision with another protoplanetary body in the asteroid belt between Mars and Jupiter.
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