Richardton meteorite

Richardton is a classified as an H5 chondrite meteorite. He fell in North Dakota, USA on June 30, 1918. A total of 90 kg, were recovered.

In Richardton an excess of xenon isotope 129Xe was detected first time in 1960. This xenon isotope is produced by decay of short-lived radionuclide 129I and shows that this must have been present to the formation of the solar system in the protoplanetary disk. This was thus the first evidence for the existence of such short-lived radionuclides in the protoplanetary disk. Today, many more radionuclides are known to have existed at that time, such as 26Al, 53Mn, 60FE.

The existence of such radionuclides is important information if you want to understand the processes in the protoplanetary disk. It is believed that especially 26Al and possibly 60FE as an energy source for heating, which led to the melting and differentiation of asteroids played a role. 60FE can probably be produced only in a supernova, so this is an indication that material from a supernova explosion that must have occurred very shortly before the formation of the solar system in the solar nebula from which formed the solar system, introduced been. Maybe the shock wave of this supernova explosion that caused the compression of the solar nebula only.

Many of these radionuclides are now used for relative dating of material from the time of formation of the solar system. Richardton itself was dated to 4.558 billion years with I- Xe.Methode, while the Mn -Cr age is 4.5563 billion years. Since both methods are relative dating methods, they were calibrated using uranium - lead dating to specify absolute age can. Direct dating by the uranium-lead - dating which is carried out at from phosphates Richardton gave an age of 4,551,400,000 years.

This age probably do not predate the original crystallization, but the later thermal metamorphism of asteroids originating from the Richardton. Since the isotope uranium-lead system closes at lower temperatures than Mn - Cr or I- Xe, the difference in the aging is likely to reflect the slow cooling this asteroids.