The Geologically Recent Giant Impact Basins at Vesta's South Pole

Dawn's global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features. These large basins provide exceptional windows into impact processes at planetary scales. The youngest Rheasilvia, is 500 kilometers wide and 19 kilometers deep...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2012-05, Vol.336 (6082), p.694-697
Main Authors: Schenk, Paul, O'Brien, David P., Marchi, Simone, Gaskell, Robert, Preusker, Frank, Roatsch, Thomas, Jaumann, Ralf, Buczkowski, Debra, McCord, Thomas, McSween, Harry Y., Williams, David, Yingst, Aileen, Raymond, Carol, Russell, Chris
Format: Article
Language:English
Subjects:
Asteroids
Astronomy
Astrophysics
Basins
Convergence
Deposition
Ejecta
Evolution
Fracture mechanics
Geology
Geomorphology
Impact basins
Impact craters
Impact melts
Massifs
Meteorite craters
Meteorites
Polar regions
Saturnian satellites
Scarps
Solar system
South Pole
Spacecraft
Topography
Vesta asteroid
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Summary:Dawn's global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features. These large basins provide exceptional windows into impact processes at planetary scales. The youngest Rheasilvia, is 500 kilometers wide and 19 kilometers deep and finds its nearest morphologic analog among large basins on low-gravity icy satellites. Extensive ejecta deposits occur, but impact melt volume is low, exposing an unusual spiral fracture pattern that is likely related to faulting during uplift and convergence of the basin floor. Rheasilvia obliterated half of another 400-kilometer-wide impact basin, Veneneia. Both basins are unexpectedly young, roughly 1 to 2 billion years, and their formation substantially reset Vestan geology and excavated sufficient volumes of older compositionally heterogeneous crustal material to have created the Vestoids and howardfte-eucrite-diogerrite meteorites.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1223272