Iron rich basaltic eucrites, implication on spectral properties and parental bodies
C. Carli, M. Ciarniello, A. Migliorini, G. Pratesi
In Press, Journal Pre-proof, Available online 14 August 2021
• VNIR absorption positions of eucrite shift at wavelength longer than typical basaltic achondrites.
• Absorption shifts are coherent with differences in pyroxenes composition and texture.
• Basaltic eucrites with a fast cooling history show VNIR absorption at longer wavelength than other eucrites.
• Those eucrites show a BCI/BAR relationship indicating some S-type instead V-type parental body.”
“The Howardites-Eucrite-Diogenite achondrite family is recognized to be the set of extraterrestrial rocks coming from (4) Vesta and Vestoids. In fact, the similar values of oxygen isotopes, and some chemical variation permit to associate these rocks to a system genetically correlated. Reflectance spectral properties permit an association between these achondrites and the (4) Vesta and Vestoids crust. Despite this closer connection, some Eucrites show spectral properties comparable with their pyroxene composition but strongly shifted, in terms of spectral parameters, with respect to the values retrieved for their parental bodies. The results from this work show how these eucrites have an evident shift of the main absorptions without peculiar geochemical variation within the family with respect to the data of the supposed parental body.
Here, we evidence how these eucrites show an iron enriched pigeonite indicating these samples underwent a very quick cooling which could be associated to erupting material onto the surface of its parental body. Their distribution on the surface could be then limited to small areas that could be detected only at high spatial resolution on (4) Vesta or Vestoids. Nevertheless, the relationship among band center I and the band area ratio show how these samples could also fit with parental bodies shifted from the typical basaltic achondrites regions and moving closer to the characteristics of other pyroxenes enriched material like SIII-SV type Asteroids.”