Characterization of Hydrated, Layered Deposits at the Valles Marineris Plateau from SHARAD, HiRISE, and CRISM, a Multidisciplinary Approach

Characterizing the nature of surface materials on Mars is essential for determining the past and present climate and for assessing future landing sites. In particular, sedimentary surface materials may contain a record of habitability, the water cycle and variability, atmospheric circulation, and geologic surface processes. The materials may be investigated by a diverse suite of orbital instruments, and a greater variety should lead to better characterization. Critical to the characterization of surface materials is understanding their mineralogical and physical properties, including their composition and distribution. Whereas materials are spread non-uniformly over the Martian surface, many deposits exist in locations that are difficult to measure with one or more instruments, impeding full characterization. In rare cases many orbiting instruments are able to train on a single deposit or multiple deposits in their entirety. We have located several of these deposits near the rim of Valles Marineris (VM) and neighboring chasmata that may be characterized by optical imagery, spectroscopy, thermal behavior, and now, sounding radar.

Our objective is to constrain the chemical and physical properties of sedimentary deposits on the Valles Marineris rim and to test
the various hypotheses of their origin. Multidisciplinary approaches such as this are difficult on Mars, either because surface characteristics make the application of radar impossible or because of a lack of exposure limiting access with other instruments. Thus, the Valles Marineris plateau deposits may serve as an ideal test location for understanding altered sedimentary deposits on Mars.

Central to our investigation is combining multidisciplinary techniques that characterize layered deposits in various ways. In light of that, we will use data from SHARAD, HiRISE, CTX, CRISM, THEMIS, TES, and HRSC. As an ensemble, these instruments provide views of the LLD that are more complete than in previous studies. Recent increases in coverage with high resolution imagery, digital terrain models (DTMs), and spectral images will enhance the return.

In support of many goals of the Mars Data Analysis Program (MDAP) and the Mars Exploration Program Analysis Group (MEPAG), we will combine datasets from several instruments and missions to determine the physical and compositional characteristics of the LLD and to test the open hypotheses of LLD formation: (1) lacustrine sedimentary deposition, (2) volcanic deposition, or (3) aeolian/airfall deposition [Weitz et al., 2010, and references therein]. Furthermore, we will look for evidence that the LLD have a common source or alteration sequence and test scenarios of LLD deposition occurring before and after VM formation and growth.

Products and results we will generate to test hypotheses include: maps of full extent, thickness and volume of LLD over entire region, with a full 3D reconstruction; maps of spectral components and alteration minerals in a stratigraphic context; extracted geophysical and thermophysical properties for each location; constraints on the relative timing and duration of deposition and alteration; constraints on the hydrologic and tectonic settings during deposition; and constraints on the porosity and density of LLD.