HR: 1340h
AN: P13D-1562    [Abstracts]
TI: Sedimentary Fan Deposits in Jezero Crater Lake, in the Nili Fossae Region, Mars: Meter- scale Layering and Phyllosilicate-Bearing Sediments
AU: * Fassett, C I
EM: Caleb_Fassett@brown.edu
AF: Dept. of Geological Sciences, Brown University, Box 1846, 324 Brook St., Providence, RI 02912, United States
AU: Ehlmann, B L
AF: Dept. of Geological Sciences, Brown University, Box 1846, 324 Brook St., Providence, RI 02912, United States
AU: Head, J W
AF: Dept. of Geological Sciences, Brown University, Box 1846, 324 Brook St., Providence, RI 02912, United States
AU: Mustard, J F
AF: Dept. of Geological Sciences, Brown University, Box 1846, 324 Brook St., Providence, RI 02912, United States
AU: Schon, S C
AF: Dept. of Geological Sciences, Brown University, Box 1846, 324 Brook St., Providence, RI 02912, United States
AU: Murchie, S L
AF: JHU-APL, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AB: Sedimentary deposits that are clearly related to valley networks on Mars are relatively unusual and have been recognized in only a few locations on Mars. However, such sediments have the potential to preserve an excellent record of the surface environment at the time of their emplacement, including data on the potential habitability of the surface, which makes them important targets of study for both orbital and landed missions. An exceptional example of valley network-derived sedimentary deposits is located in Jezero crater, a ~40-km diameter impact crater, northwest of the Isidis Basin near the Nili Fossae (centered at 77.6 E and 18.4 N). Two valleys debouch into this crater from the west and north, and each valley appears to have deposited a sedimentary fan. On the eastern end of the crater, an outlet valley is observed, and based on the elevation of the outlet valley, Jezero crater must have contained a sizeable lake at one time, with a volume of at least 250 km³, of comparable volume to terrestrial Lake Tahoe (V ~ 160 km³). The fan deposits have been interpreted as deltaic sediments, deposited into this lake. New data from MRO and other recent missions has motivated the reexamination of Jezero crater and its sedimentary deposits. Meter-scale layering is commonly observed on fan deposits in HiRISE data. Layers appear to dip gently (<10-15°) and outcrop in sinuous patterns. Many unconformities are discernable between packets of the layered material. We interpret these sediments as having been deposited via lateral accretion during meander migration, with observed unconformities resulting from numerous channel switching events on the fan. CRISM visible/near-infrared observations of the fan materials indicate that where these light- toned, finely-layered packets of sedimentary material are exposed, they commonly have spectra consistent with iron-magnesium phyllosilicate. Phyllosilicates are also found on the Jezero crater interior off the margins of the primary deposits. Given both the unique geological setting and mineralogy of the Jezero crater fan materials, it is a prime target for future landed missions, such as MSL.
DE: 1861 Sedimentation (4863)
DE: 5400 PLANETARY SCIENCES: SOLID SURFACE PLANETS
DE: 5419 Hydrology and fluvial processes
DE: 5470 Surface materials and properties
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting