Gaining Insight into Surface Geologic Processes on Europa through Geologic mapping at Global and Regional Scales

Evaluating the potential habitability of the icy ocean worlds of the outer planets requires an understanding of three main components, the chemistry and composition of the material making up the body, the sources of chemical disequilibrium available for potential metabolic processes, and the geology that drives the interaction between the surface and the deeper interior of the body. For Europa, we have focused on the latter area, creating a global geologic map at the scale of 1:15M. The geologic units can be divide into four categories: (1) crater materials and subunits of continuous crater ejecta and discontinuous crater ejecta—including the primary impact crater and its local deposits and farther ranging ejecta material; (2) Various morphological types of chaos materials identified as high albedo, mottled, low albedo, and knobby chaos—disrupted terrains; (3) General band forming material and high albedo bands—linear to curvilinear zones with a distinct, abrupt albedo change from the surrounding region; and (4) ridged plains—distributed across all latitudes and characterized by subparallel to cross-cutting ridges and troughs. In addition, a number of structural features are identified including: depression margins, troughs, multi-ring structures, cycloids, band linea, ridges, undifferentiated linea, and microchaos. The distribution of microchaos is not uniform across the surface, showing a general association with band forming materials. Concentrations might correspond to areas of crustal weakness or thinning.

Upon completion of the global geologic map, we identified seven distinct regional scale images/mosaics (100's of m/pixel) covering 10% of the surface that allow greater characterization of each global unit. Preliminary assessment of the Conamara Chaos and part of the Manannan regions show that the ridged plains contain a greater abundance of band units that can be used as distinct stratigraphic markers. In addition, many of the outcrops of microchaos are surrounded by a halo of smooth, dark material that appears to embay the surrounding terrain, providing greater insight into potential cryomagmatic processes. In this presentation we will discuss the link between the global and regional-scale geologic units, their distribution across Europa, and implications for future Europa exploration.