Vestan lithologies mapped by the visual and infrared spectrometer on Dawn

Eleonora Ammanito1, Maria C. De Sanctis1, Fabrizio Capaccioni1, M. Teresa Capria1, F. Carraro1, Jean-Philippe Combe2, Sergio Fonte1, Alessandro Frigeri1, Steven P. Joy3, Andrea Longobardo1, Gianfranco Magni1, Simone Marchi4, Thomas B. McCord2, Lucy A. McFaddens5, Harry Y. McSween6, Ernesto Palomba1, Carle M Pieters7, Carol A. Polanskey8, Carol A. Raymond8, Jessica M. Sunshine9, Federico Tosi1, Francesca Zambon1 and Christopher T. Russell3

1Istituto di Astrofisica e Planetologia Spaziali, INAF, Rome, Italy
2Bear Fight Institute, 22 Fiddler’s Road, Box 667, Winthrop, Washington 98862, USA
3Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095–1567, USA
4NASA Lunar Science Institute, Southwest Research Institute, 1050 Walnut St, Suite 300, Boulder, Colorado 80302, USA
5NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
6Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996–1410, USA
7Department of Geological Sciences, Brown University, Providence, Rhode Island 02912, USA
8Jet Propulsion Laboratory, Pasadena, California 91109, USA
9University of Maryland, College Park, Maryland 20742–2421, USA

We present global lithological maps of the Vestan surface based on Dawn mission’s Visible InfraRed (VIR) Spectrometer acquisitions with a spatial sampling of 200 m. The maps confirm the results obtained with the data set acquired by VIR with a spatial sampling of 700 m, that the reflectance spectra of Vesta’s surface are dominated by pyroxene absorptions that can be interpreted within the context of the distribution of howardites, eucrites, and diogenites (HEDs). The maps also partially agree with the ground and Hubble Space Telescope observations: they confirm the background surface being an assemblage of howardite or polymict eucrite, as well as the location of a diogenitic-rich spot; however, there is no evidence of extended olivine-rich regions in the equatorial latitudes. Diogenite is revealed on the Rheasilvia basin floor, indicating that material of the lower crust/mantle was exposed. VIR also detected diogenites along the scarp of Matronalia Rupes, and the rims of Severina and a nearby, unnamed crater, and as ejecta of Antonia crater. The diogenite distribution is fully consistent with petrological constraints; although the mapped distribution does not provide unambiguous constraints, it favors the hypothesis of a magma ocean.

Reference
Ammanito E, Sanctis MC, Capaccioni F, Capria MT, Carraro F, Combe JP, Fonte S, Frigeri A, Joy SP, Longobardo A, Magni G, Marchi S, McCord TB, McFaddens LA, McSween HY, Palomba E, Pieters CM, Polanskey CA, Raymond CA, Sunshine JM, Tosi F, Zambon F and Russell CT (2013) Vestan lithologies mapped by the visual and infrared spectrometer on Dawn. Meteoritics & Planetary Science (in press)
Published by arrangement with John Wiley & Sons

[doi:10.1111/maps.12192]

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