Chondrule Formation by Impact?
The CB chondrites (at least Gujba and HH 237) formed after the solar nebula had finished being energetic. Yet their formation indicates an energetic process was involved.
For example, the metal was melted and some seems to have formed from a vapor. Chondrules were totally molten droplets that contained no pre-existing debris and cooled rapidly. All these features point a cosmic finger at formation during an impact event.
In a collision between large objects, there is a lot of vaporization and melting. These hot conditions provide settings in which metal nodules and skeletal olivine chondrules form by melting, and cryptocrystlline chondrules (which are smaller) are made by condensation from a vapor.
There are no unmelted remnants of the original materials left in these meteorites. This is consistent with their formation by impact between two objects the size of Earth's Moon. Such a monumental collision would separate melt and vapor from unmelted materials.
Collision between two Moon-sized (or larger) objects in the early Solar System would have produced vast amounts of melt and vapor, from which the components in CB chondrites could have formed. Such impacts may have been common for a few million years early in the evolution of the Solar System.
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