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Pits, Spots, Uplifts, and Small Chaos Regions on Europa: A Search for Regional Variations

Introduction: Europa’s surface is littered with features that may reveal tantalizing information about its interior and geologic history. This work focuses on features created by subsurface upwellings: pits, uplifts, spots and chaos. Several groups have worked on mapping these features in the past. Greenberg et al. [1] mapped sub-circular features with clear topographic expressions, but explicitly left out chaos regions previously mapped [2, 3]. This work concluded that a continuous range of feature sizes existed, with increasing numbers of small features, down to the resolution limit. They consider this distribution to be in support of a “melt-through” model of feature formation, where localized heating thins the shell exposing water below. Near-equatorial mapping by [4, 5] focused on large and small chaos regions, but also noted pits and other features. This mapping found a peak in size distribution near ~5 km and declining numbers of smaller features. This distribution was interpreted as an indication of a diapiric formation model. The purpose of this work is to consider all subsurface disruptions but focus on smaller features: pits, spots, uplifts, and small chaos regions. The mapping method is described below. The long-term objective is to obtain data that can be used to investigate regional variation in spatial and size frequency distributions. The sample area presented below illustrates the potential for exploring the distribution of pits, spots, uplifts and chaos on Europa.