Paper No. 8
Presentation Time: 10:15 AM


GOUDGE, Timothy A.1, MUSTARD, John F.1, HEAD, James W.2, FASSETT, Caleb I.3 and RUSSELL, James M.2, (1)Department of Geological Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912, (2)Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, (3)Department of Astronomy, Mount Holyoke College, South Hadley, MA 01075,

Jezero crater is an ~40 km diameter impact crater in the Nili Fossae region of Mars whose rim is breached by two inlet valleys and an outlet valley, indicating that the crater once hosted a hydrologically open lake (area = ~1220 km2). Additionally, Jezero crater contains two delta deposits that host Fe/Mg-smectite and Mg-carbonate. It has been hypothesized that the secondary minerals within the basin are detrital in nature, as opposed to having formed in situ. Here we present new work on mineralogic and geomorphic mapping of the Jezero crater paleolake and its associated watershed in order to further test this hypothesis.

Geomorphic mapping is completed at a scale of 1:100,000 using a mosaic of Context Camera (CTX) images (~6 m/pixel), and the mineralogy of the major units is investigated using hyperspectral reflectance data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM; ~18 m/pixel). The mineralogy of the major units within the watershed is compared to the mineralogy of the sedimentary units within the paleolake basin to determine if the ‘source to sink’ hypothesis can be validated.

The regional geomorphic mapping reveals several distinct units, and we have developed a regional stratigraphy to determine which units would have been available to supply sediment to the Jezero crater paleolake through erosion and transport. Initial results indicate a distinct difference in mineralogy between the two delta deposits (the western delta is Fe/Mg-smectite rich, while the northern delta is Mg-carbonate rich), and that both types of secondary minerals are observed within the watershed in units that are cut by fluvial features associated with the paleolake system.

We are also investigating the source to sink mineralogy of lacustrine sediment from the terrestrial analog Lake Towuti, Indonesia, a large (area = ~560 km2), hydrologically open lake with a watershed that is primarily composed of lateritic soils derived from, and overlain on, the ultramafic East Sulawesi Ophiolite. The ‘source to sink’ components of the Lake Towuti system are analyzed with reflectance spectroscopy and XRD to determine the mineralogy of input sediment (bed and suspended load) in comparison to lacustrine sediment. These data will be used to further understand what, if any, type of in situ alteration might be expected in this environment.