Ridged Plains on Europa Reveal a Compressive Past

Post Contributed by Dr. Erin Leonard, Postdoctoral Fellow at the Jet Propulsion Laboratory, California Institute of Technology

Jupiter’s icy moon Europa has a geologically young surface (60-100 million years old), as evidenced by the sparsity of large impact craters. Studying the surface features on Europa allows insight into how resurfacing may have given it a youthful appearance. The majority of Europa’s young surface is made up of Ridged Plains terrain. This terrain has not been extensively studied before because it appears as a smooth and relatively bland in the global-scale images. However, in the few high-resolution images returned by the Galileo mission in the early 2000s, the Ridged Plains are revealed to consist of numerous ridges and troughs that have a range of morphologies—from crisscrossing each other in various directions to orderly sets of parallel structures (Image 1). But how did these ridges and troughs form?

LeonardFigure1

Image 1: A variety of examples of ridged plains on Europa. Note the linear to curvilinear systematic ridge traces in all examples: (A) observation E4ESDRKMAT02 at 26 m/pixel, (B) observation 19ESRHADAM01 at 66 m/pixel, (C) observation 12ESWEDGE_02 at 29 m/pixel, and (D) observation 12ESMOTTLE02 at 16 m/pixel.

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Experimental Delta Formation in Crater Lakes

Post by G. de Villiers, Faculty of Geoscience, Utrecht University.

Fan-shaped deposits have been identified on the surface of Mars (Image 1). These sediment bodies often occur within impact craters and, specifically in the cases of fan deltas, suggests that these craters were once lakes early in Martian history. Fan delta morphologies are indicative of upstream (e.g. flow discharge and sediment properties) and downstream (e.g. basin characteristics) parameters, from which the hydrological conditions at the time of formation can be inferred (e.g. Kleinhans et al. 2010).

IAGFigure1

Image 1: Examples of fan delta deposits on Mars, formed in enclosed impact crater or rift basins. A) Single-scarped, branched prograding delta (PSP_006954); B) Single-scarped, smooth prograding delta (I10805012); and C) Multiple-scarped, stepped retrograding delta (V17040003). White line is approximately 5 km.

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