RECONSTRUCTION OF THE SURFACE OF JUPITER'S MOON EUROPA: A SEQUENCE OF EVENTS NEAR THE SOUTH POLE

High-resolution images of a region near the south pole of Europa allow reconstruction of a series of events, tectonic and thermal, that displaced and modified the surface. This approach is complementary to regional geological mapping, which is based on less detailed images, but covers a broader sample of the surface. The events reconstructed in this locale resurfaced about half the area or more, so they probably ranged over a substantial fraction of the age of Europa's surface, which in itself is quite young (< 50 Myr), due to the cumulative effects of such local (or regional) reprocessing events acting over the entire globe. Thermally produced chaotic terrain formed both early and late in the sequence, interleaved with tectonic events such as cracking, ridge-formation, crack dilation, and strike-slip displacement. Trends in changing geological processes that had been inferred from regional geological mapping efforts, especially an increase in formation of chaotic terrain with time, which had been widely interpreted as implying a thickening of the ice crust, are not evident in this area. The impression that chaotic terrain is a relatively recent phenomenon may come from the fact that older chaotic terrain can be more difficult to identify, especially in the lower-resolution images used for geological mapping.