The origin of high-temperature minerals in carbonaceous chondrites

It is suggested that carbonaceous chondrites are significantly younger than ordinary and enstatite chondrites. Consequently, they were not heated by the elements having short-lived radioactivities which were probably responsible for the thermal evolution of ordinary (and enstatite) chondrites. During the evolution of the parent bodies of ordinary (and enstatite) chondrites, substantial quantities of high-temperature mineral fragments escaped, owing to explosive volcanism and collisions. This detritus, derived from different sources, became mixed and was present in the general region where accretion of the characteristic low temperature minerals of carbonaceous chondrites subsequently occurred. As a result, many carbonaceous chondrites are found to contain nonequilibrium inclusions of early high-temperature minerals.