Paper in Press
GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2012GL052959
Large-scale troughs on Vesta: A signature of planetary tectonics
- The large scale troughs on Vesta are fault-bounded graben, not simple fractures.
- It is likely that the troughs formed as a result of giant impact.
- Vesta's differentiated interior is likely why graben formed instead of fractures.
Images of Vesta taken by the Dawn spacecraft reveal large-scale linear structural features on the surface of the asteroid. We evaluate the morphology of the Vesta structures to determine what processes caused them to form and what implications this has for the history of Vesta as a planetary body. The dimensions and shape of these features suggest that they are graben similar to those observed on terrestrial planets, not fractures or grooves such as are found on smaller as-teroids. As graben, their vertical displacement versus length relationship could be evaluated to describe and interpret the evolution of the component faults. Linear structures are commonly observed on smaller asteroids and their formation has been tied to impact events. While the orientation of the large-scale Vesta structures does imply that their formation is related to the impact events that formed the Rheasilvia and Veneneia basins, their size and morphology is greatly different from impact-formed fractures on the smaller bodies. This is consistent with new analyses that suggest that Vesta is fully differentiated, with a mantle and core. We suggest that impact into a differentiated asteroid such as Vesta could result in graben, while grooves and fractures would form on undifferentiated asteroids.
Received 29 June 2012; accepted 25 August 2012.
Citation: (2012), Large-scale troughs on Vesta: A signature of planetary tectonics, Geophys. Res. Lett., doi:10.1029/2012GL052959, in press.