Structure of Vestan crust inferred from thermal history of diogenites

Abstract

We studied thermal history of diogenites to better understand the formation processes of the crust of the parent body, asteroid 4 Vesta. We found diogenites that preserve chemical zoning in pyroxene. These diogenites cooled rapidly from the melt near the surface. The fact argues against the idea that diogenites were plutonic rocks from the lower crust. We suggest that parent magmas of diogenites intruded into the early-formed eucritic crust, and some of which cooled rapidly near the surface. This model is consistent with the geochemical evidence that parent magmas of some diogenites were interacted with eucrites.