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| Titel |
Vesta Compositional Diversity in Quadrangle Av-13 Tuccia |
| VerfasserIn |
C. Pieters, M. C. De Sanctis, E. Ammanito, J. Y. Li, A. Nathues, T. Kneissl, R. Jaumann  , V. Reddy, L. Le Corre, K. Stephan, F. Prusker, F. Capaccioni, E. Palomba, F. Tosi, F. Zambon, E. Palmer, C. A. Raymond, C. T. Russell |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250064501
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| Zusammenfassung |
| The Dawn spacecraft is currently orbiting the main belt asteroid 4 Vesta to evaluate the
character of this small protoplanet and its role in early solar system evolution. Compositional
data from the Gamma Ray and Neutron Detector (GRaND) are being acquired
and will be available soon. Spectral data acquired with the Visible and Infrared
Mapping Spectrometer (VIR) and the Framing Camera (FC) instruments provide
compositional information in a spatial context. Available VIR data provide the
high spectral resolution necessary for mineral identification and characterization
while FC data provide selected spectral channels, but at a higher spatial resolution
that enable geologic relations to be better discerned. As these different data are
integrated and analyzed, broad compositional variations are observed in the mineralogy
across Vesta. The diversity seen on a global scale and direct associations with HED
mineralogy is discussed in DeSanctis et al. and Ammannito et al. [this meeting]. Geologic
mapping of Vesta has been initiated for 15 well-defined quadrangles and coordinated
mineralogical mapping has commenced at that higher scale. We discuss the mineralogical
diversity observed in quadrangle Av-13 Tuccia, which spans a region between 21Ë -66Ë
S latitude and 180Ë -270Ë E longitude on Vesta. The Av-13 Tuccia quadrangle
includes three major geologic terrains [see Kneissl et al., this meeting]: Vestalia Terra
located in the north of the quadrangle, the Equatorial Cratered Terrain, and the
Ridge-and-Groove Terrain which is part of the Rheasilvia Formation. As such, the
Tuccia quadrangle includes regions which transition from the equatorial terrain to
the giant impact basin of Rheasilvia. Prominent spectral variations are mapped
across the surface by FC and VIR, largely associated with relatively fresh impact
craters. Diagnostic absorption bands of pyroxene are readily detected. The relative
strength of these absorptions is seen to vary in a regular spatial context, largely
correlated with overall albedo of surface material and often at high spatial resolution
associated with individual features. Diagnostic variations in absorption band center and
shape are also observed. Deposits of an unusual crater located on a steep slope at
59Ë S, 200Ë E exhibits some of the shortest, most symmetric absorption bands
(e.g., centered near 0.920-0.925 μm), but with highly variable band strength in a
well-defined spatial context. In contrast, the small fresh crater to the north on the
rim of Tuccia crater has exposed material of a different composition that exhibits
broader diagnostic absorption bands centered at a longer wavelength, suggestive
of pyroxenes that are slightly more Fe-rich. As VIR and FC data continue to be
acquired, processed and integrated, additional details of the mineral character and
diversity of Vesta will be revealed in order to discern local and regional geologic
evolution.
The authors are grateful for the dedication of the Dawn Instrument and Operations Teams
and for support from NASA’s Discovery Program and Dawn’s international partners. |
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