Seymchan
A brief description:
Type: stony-iron meteorite, pallasite
Meteorite impact site: Russia, Magadan region
The time of the meteorite fall: not fixed
Date of discovery: 1967
History of study
A.F. Mednikov found meteorite fragments in the summer of 1967, during the geological expedition in the Khekandya River area. A large metal block weighing 272 kg lay in a dry streambed. Another fragment, smaller in size (51 kg), was found with the help of a mine detector in October of the same year. The specimens were sent to the Committee on Meteorites of the USSR Academy of Sciences in Moscow. Since the found fragments consisted entirely of metal, the Seymchan meteorite was classified as iron and did not arouse much interest. As a result, the meteorite was "forgotten" for 40 years, until 2004. During a new expedition to this remote taiga region, meteorite fragments containing olivine grains were found. In 2007, scientists carried out repeated studies and comparison of the composition of old and new specimens. The results of the study showed that the Seymchan meteorite belongs to the pallasites of the main group, one of the rarest types of meteorites.
General information
The Seymchan meteorite is a fragment of one of the ancient protoplanets that arose and collapsed at the dawn of the formation of the solar system.
Chemical composition: 80-90% iron, 9.15% nickel, an admixture of iridium,
gallium and germanium. The metal parts of the meteorite have a clearly visible pattern of Widmanstätten lines. Such a pattern is being formed in space conditions during the cooling and crystallization processes in the iron-nickel matrix over the course of millions years. It serves as an important diagnostic feature in the study of meteorites.
The heterogeneity of the structure and the iron-olivine composition are
characteristic of the boundary layers between the core and the mantle of a large celestial body. This is the reason for the rarity of pallasites. Only 38 such findings are known worldwide. Such an origin also indicates considerable age of the specimens. The Seymchan meteorite was formed 4.5 - 4 billion years ago, before life arose on our planet.
It is difficult to estimate the exact time of the meteorite fall, however according to calculations, it happened no later than two and no earlier than one hundred thousand years ago. A cosmic body with a total mass of about 60 tons entered the Earth's atmosphere disintegrated and turned into a meteor shower over an area of about 15 km2. Most likely, occurred during the last ice age. Fragments of the meteorite fell to the surface of the glacier and were carried into the river valley, where they were found in 1967.
