Showing that
chondrules are as old as CAIs addresses a long-standing question of why
chondrule formation should be delayed by up to 2 million years after CAIs.
Most stony meteorites contain
chondrules. Using a jeweler's loupe that magnifies at least 10 x , one can usually spot these tiny spherical inclusions on a chondrite's surface.
Benton reveals a sequence of events that reflect a complex history: (1)
chondrule formation and initial assembly; (2) brecciation; (3) thermal metamorphism and (4) shock veining.
They derive their name from their main component --
chondrules, which formed as molten droplets floating in space.
This technique enabled the researchers to study the orientation and position of individual micrometre-sized grain particles that had coalesced around the
chondrule.
Chondrules themselves formed through quick melting events in the dusty gas cloud -- the solar nebula -- that surrounded the young sun.
"With their high precision measurements, they are able to date formation times for
chondrules very precisely," he said.
Achondrites (which lack
chondrules) are prized by scientists and collectors alike because they come from the Moon, Mars, the asteroid Vesta, and other geologically differentiated bodies.
These findings suggest that
chondrules formed from 2 million to 5 million years after inclusions appeared.
The early family tree of our solar system's rocky planets features tiny glassy spheres called
chondrules, found today inside ancient meteorites.
In the equivalent of nine pages, you get a fast-forward account of how the solar system came to be, and in the process you are introduced to such terms as refractory inclusions,
chondrules, and devolatilized.