Heating, Cooling, and Cratering:
One Asteroid’s Complicated Story
Dewar area
PSRDpresents
www.psrd.hawaii.edu/July08/H-chondrite-parent.html
Heating, Cooling, and Cratering:
One Asteroid’s Complicated Story
The simplest way to explain the sequence of textural and
mineralogical changes among H chondrites is by thermal
metamorphism in a hot body. This ‘onion-shell’ structure
results in the most metamorphosed rocks residing the
deepest and cooling the slowest.
PSRDpresents
www.psrd.hawaii.edu/July08/H-chondrite-parent.html
Heating, Cooling, and Cratering:
One Asteroid’s Complicated Story
Two studies of chondrite ages show that the onion shell model is consistent
with observations. Cooling is slower for the more metamorphosed
chondrites.
PSRDpresents
www.psrd.hawaii.edu/July08/H-chondrite-parent.html
Heating, Cooling, and Cratering:
One Asteroid’s Complicated Story
Some cooling rates derived from compositional zoning in metallic minerals are
consistent with the onion-shell structure.
But others are not. Why?
Perhaps a large impact event brought slower-cooling rock closer to the surface
and buried faster-cooling rock.
PSRDpresents
www.psrd.hawaii.edu/July08/H-chondrite-parent.html