Researchers have discovered minerals from 43 meteorites that landed on Earth 470 million years ago. More than half of the mineral grains are from meteorites completely unknown or very rare in today’s meteorite flow. These findings mean that we will probably need to revise our current understanding of the history and development of the solar system.
The discovery confirms the hypothesis presented this summer when geology professor Birger Schmitz at Lund University in Sweden revealed that he had found what he referred to as an “extinct meteorite” — a meteorite dinosaur.
The meteorite was given the name Österplana 065 and was discovered in a quarry outside Lidköping in Sweden. The term ‘extinct’ was used because of its unusual composition, different from all known groups of meteorites, and because it originated from a celestial body that was destroyed in ancient times.
The discovery led to the hypothesis that the flow of meteorites may have been completely different 470 million years ago compared to today, as meteorites with such a composition no longer fall on Earth.
“The new results confirm the hypothesis. Based on 43 micrometeorites, which are as old as Österplana 065, our new study shows that back then the flow was actually dramatically different. So far we have always assumed that the solar system is stable, and have therefore expected that the same type of meteorites have fallen on Earth throughout the history of the solar system, but we have now realised that this is not the case,” says Birger Schmitz.
Birger Schmitz conducted the study together with his colleagues at Lund University, the University of Chicago, and the University of Wisconsin-Madison. The result was unexpected. Birger Schmitz is convinced that something so far unknown but of fundamental importance in the history of the solar system occurred nearly 500 million years ago.
He also emphasises that the new study shows that it is possible to make highly detailed reconstructions of the changes that have occurred in the solar system.
“We can now recreate late history of not only the Earth but of the entire solar system. The scientific value of this new report is greater than the one last summer,” says Birger Schmitz.
The method of reconstructing the meteorite flow was developed at the specially established Astrogeobiology Laboratory in Lund. In the search for the mineral grains (chromium oxides) that fell on Earth together with the meteorites, the researchers used different acids to dissolve several tons of sediment from the ancient seabed. The chromium oxides were subsequently analysed to identify their composition and oxygen isotopes. This made it possible to determine from which type of meteorites the grains originated.
Philipp R. Heck, Birger Schmitz, William F. Bottke, Surya S. Rout, Noriko T. Kita, Anders Cronholm, Céline Defouilloy, Andrei Dronov, Fredrik Terfelt. Rare meteorites common in the Ordovician period. Nature Astronomy, 2017; 1: 0035 DOI: 10.1038/s41550-016-0035