Advanced

Olivine on Vesta as exogenous contaminants brought by impacts : Constraints from modeling Vesta's collisional history and from impact simulations

Turrini, D.; Svetsov, V.; Consolmagno, G.; Sirono, S. and Pirani, S. LU (2016) In Icarus 280. p.328-339
Abstract

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected... (More)

The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected olivine originated was a matter of debate. Later works raised instead the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work, we quantitatively explore the proposed scenario of a exogenous origin for the detected vestan olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid over the last one or more billion years. To perform this study we took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, a model we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by the same impacts that shaped the vestan surface can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite–Eucrite–Diogenite family of meteorites.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Asteroid Vesta, Asteroids, Asteroids, composition, Asteroids, surfaces, Impact processes
in
Icarus
volume
280
pages
12 pages
publisher
Academic Press
external identifiers
  • scopus:84990038761
  • wos:000384629200023
ISSN
0019-1035
DOI
10.1016/j.icarus.2016.07.009
language
English
LU publication?
yes
id
495b8e89-8028-44d4-9402-c1bd19df912b
date added to LUP
2016-10-20 10:37:39
date last changed
2017-10-01 05:24:43
@article{495b8e89-8028-44d4-9402-c1bd19df912b,
  abstract     = {<p>The survival of asteroid Vesta during the violent early history of the Solar System is a pivotal constraint on theories of planetary formation. Particularly important from this perspective is the amount of olivine excavated from the vestan mantle by impacts, as this constrains both the interior structure of Vesta and the number of major impacts the asteroid suffered during its life. The NASA Dawn mission revealed that olivine is present on Vesta's surface in limited quantities, concentrated in small patches at a handful of sites not associated with the two large impact basins Rheasilvia and Veneneia. The first detections were interpreted as the result of the excavation of endogenous olivine, even if the depth at which the detected olivine originated was a matter of debate. Later works raised instead the possibility that the olivine had an exogenous origin, based on the geologic and spectral features of the deposits. In this work, we quantitatively explore the proposed scenario of a exogenous origin for the detected vestan olivine to investigate whether its presence on Vesta can be explained as a natural outcome of the collisional history of the asteroid over the last one or more billion years. To perform this study we took advantage of the impact contamination model previously developed to study the origin and amount of dark and hydrated materials observed by Dawn on Vesta, a model we updated by performing dedicated hydrocode impact simulations. We show that the exogenous delivery of olivine by the same impacts that shaped the vestan surface can offer a viable explanation for the currently identified olivine-rich sites without violating the constraint posed by the lack of global olivine signatures on Vesta. Our results indicate that no mantle excavation is in principle required to explain the observations of the Dawn mission and support the idea that the vestan crust could be thicker than indicated by simple geochemical models based on the Howardite–Eucrite–Diogenite family of meteorites.</p>},
  author       = {Turrini, D. and Svetsov, V. and Consolmagno, G. and Sirono, S. and Pirani, S.},
  issn         = {0019-1035},
  keyword      = {Asteroid Vesta,Asteroids,Asteroids, composition,Asteroids, surfaces,Impact processes},
  language     = {eng},
  month        = {12},
  pages        = {328--339},
  publisher    = {Academic Press},
  series       = {Icarus},
  title        = {Olivine on Vesta as exogenous contaminants brought by impacts : Constraints from modeling Vesta's collisional history and from impact simulations},
  url          = {http://dx.doi.org/10.1016/j.icarus.2016.07.009},
  volume       = {280},
  year         = {2016},
}