Giebner, Tanja

Jaumann, R.

Krohn, Katrin

Schröder, S.E.

Institute of Transport Research:Publications

P43C-2130: Anomalous crater Marcia on asteroid 4 Vesta: Spectral signaturesand their geological relationshipThursday, 15 December 201613:40 - 18:00Moscone South - Poster HallDAWN Framing Camera (FC) images are used in this study to analyze the diverse spectral signatures of craterMarcia. As the FC offers high spatial resolution as well as several color filters it is well suited to resolve geologicalcorrelations on Vestas surface. Our approach comprises the analysis of images from four FC filters ( F3, F4, F5 andF6) that cover the pyroxene absorption band at 0.9 um and the comparison of Vesta data with HED meteoritespectra. We use the ratios R 750/915 (F3/F4) and R 965/830 (F5/F6) [nm] to separate HED lithologies spectrallyand depict corresponding areas on HAMO mosaics (~ 60 m/px). Additionally, higher resolution LAMO images(~ 20 m/px) are analyzed to reveal the geologic setting. In this work, Marcia is broadly classified into three spectralregions. The first region is located in the northwestern part of the crater as well as in the central peak area andshows the most HED-like signature within the Marcia region. The other two regions, with one of them alsodescribing Marcia ejecta, are spectrally further away from HED lithologies and likely display a mixing with morehowarditic-rich material associated with carbonaceous chondrite clasts and relatively higher OH and Hconcentrations (e.g., [1], [2], [3]). In general, these other two regions are also associated with thick flow featureswithin the crater, while the HED-like area does not show such prominent flows. Hence, these darker regions seemto display post-impact material inflow of the weathered howarditic surface regolith. We conclude that the Marciaimpactor likely struck through the howarditic regolith and hit the eucritic crust underneath. Depicting this HED-likesignature globally, it resides mostly in the Rheasilvia basin and ejecta blanket, as well as in very young crater ejectain the equatorial region, consistent with it being a signature of fresh basaltic crust.[1] M. C. De Sanctis et al. (2012b) The Astrophysical Journal Letters, 758:L36 (5pp)[2] T. McCord et al. (2012) Nature 491, 83-86[3] T. H. Prettyman et al. (2012) Science 338, 242-2462016 AGU Fall Meeting https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/1726071 von 2 01.12.2016 13:14AuthorsTanja Giebner *German Aerospace CenterDLR BerlinRalf JaumannGerman Aerospace CenterDLR BerlinStefan SchroederGerman Aerospace CenterDLR BerlinKatrin KrohnGerman Aerospace CenterDLR BerlinFind SimilarView Related EventsDay: Thursday, 15 December 20162016 AGU Fall Meeting https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/1726072 von 2 01.12.2016 13:14

Anomalous crater Marcia on asteroid 4 Vesta: Spectral signatures and their geological relationship

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