STRUCTURAL AND BIOLOGICAL ANALYSIS OF NORMAL FAULTS IN BASALTS IN SHEEPSHEAD MOUNTAINS, OREGON AS AN EARTH ANALOGUE FOR MARS

Earth analogues are useful tools in choosing rover landing sites that promote opportunities for finding a preserved record of life on Mars. Often these landing sites are craters that expose layers of basalt at depth. Exact Earth analogues are lacking, so determining which crater features best preserve and promote life is challenging. To overcome this obstacle, we searched for analogue sites that expose layers of basalt by other means. Normal faulting in the southern Sheepshead Mountains of southeastern Oregon, east of Steens Mountain, has exposed 16 Ma flood basalts of the Steens formation. These stacked flows are located in a dry, isolated, undisturbed high desert area and are in close proximity to playa lakes and hot springs. Although the mode of exposure for basalt layers is faulting and not cratering, this Earth analogue site is a prime area to search for ideal characteristics that promote the growth and preservation of biologic materials in exposed basalts. We studied 92 fault scarps, which includes intact fault surface and talus surface, over a ~10 km x 10 km area. Variables measured include: proportion of fault scarp that is fault surface, proportion of fault scarp that is talus surface, flow type exposed, scale of fractures in flow, percentage of intact flow, size of talus, and sorting of talus. We also used an Imperx Spectral camera to collect near-infrared imagery and calculate a vegetation index for each fault scarp. These characteristics combined with length of fault, distance to hot springs, and proximity to playas will be used to conduct a principal component analysis (PCA) to investigate which variables contribute to the growth of biological material on exposed basalts. By conducting a PCA, we will determine what the driving mechanisms are for biological material on fault scarp surfaces and crater walls by analogy. These mechanisms can be variables or combinations of variables measured in the field. Once mechanisms have been identified, we will adapt our interpretations for craters and describe the surface characteristics of an ideal crater for future rover missions.