USING TERRESTRIAL PLAYAS TO VALIDATE, EXTRAPOLATE, AND INTERPRET IN-SITU AND REMOTE SENSING DATA FROM MARTIAN PALEOLAKES (Invited Presentation)

Basins on Mars and Earth are geologically important because of their nature as sinks for fluids and sediments over areas much larger than themselves. Therefore, basins often show remarkable mineralogical and sedimentological diversity. The materials basins accumulate provide a record of previous environmental conditions. However, the ability of basins to collect materials also leads to the accumulation of dust, sands, or other mantling deposits, which may fully or partially obscure sediments that hold clues to paleoenvironments of interest (such as for astrobiology). This is particularly relevant on Mars where there is an abundance of fine-grained particulate matter on the surface and in the atmosphere. Additionally, studies of martian paleolakes have revealed widespread, post-lacustrine, modification. While some research has sought to determine the distribution and spectroscopic characteristics of dust on Mars and how to correct for it in remote sensing data, there has been a paucity of orbital studies directly addressing how surficial layers such as mantling deposits and pavements affect the interpretation of underlying sedimentary rocks. This work characterizes the compositional and thermophysical properties across paleolake basins through remote sensing, field, and laboratory analysis of five basins in the SW United States. In addition, we will evaluate how these properties may be misconstrued in remote sensing analysis, clouding paleoenvironmental interpretations. A parallel remote sensing (and where possible in situ- Gale and Jezero) study of nine martian basins is also being conducted.

We calculated thermal inertia on all of our Martian sites of interest and determined that in all but one site, the thermal inertia generally increases toward the center of the basin. A preliminary study at Lunar Lake Playa, NV demonstrated that 1) the lacustrine materials exposed at the surface had approximately constant grain size and 2) apparent thermal inertia changed from basin edge to center in tandem with presence of post-lacustrine sediments. These initial results suggest that interpretation of thermal inertia data for Martian paleolakes should be subjected to additional scrutiny. We are in the process of characterizing mineralogy in terrestrial and Martian basins.