Lithologic Mapping of HED Terrains on Vesta using Dawn Framing Camera Color Data

TL;DR

This study uses Dawn Framing Camera color data to map HED lithologies on Vesta, revealing its magmatic differentiation, impact history, and hemispherical compositional dichotomy, with diogenite-rich material indicating a differentiated crust.

Contribution

It introduces a novel application of lunar color parameters to identify and map HED terrains on Vesta, providing new insights into its petrologic evolution.

Findings

Identification of HED terrains using color parameters

Confirmation of hemispherical compositional dichotomy

Detection of diogenite-rich material in southern hemisphere

Abstract

The surface composition of Vesta, the most massive intact basaltic object in the asteroid belt, is interesting because it provides us with an insight into magmatic differentiation of planetesimals that eventually coalesced to form the terrestrial planets. The distribution of lithologic and compositional units on the surface of Vesta provides important constraints on its petrologic evolution, impact history and its relationship with Vestoids and howardite-eucrite-diogenite (HED) meteorites. Using color parameters (band tilt and band curvature) originally developed for analyzing lunar data, we have identified and mapped HED terrains on Vesta in Dawn Framing Camera (FC) color data. The average color spectrum of Vesta is identical to that of howardite regions, suggesting an extensive mixing of surface regolith due to impact gardening over the course of solar system history. Our results confirm the hemispherical dichotomy (east-west and north-south) in albedo/color/composition that has been observed by earlier studies. The presence of diogenite-rich material in the southern hemisphere suggests that it was excavated during the formation of the Rheasilvia and Veneneia basins. Our lithologic mapping of HED regions provides direct evidence for magmatic evolution of Vesta with diogenite units in Rheasilvia forming the lower crust of a differentiated object.