It is also an important stratigraphic marker. As these are narrow negative relief features with no apparent albedo signature, they require low-Sun imaging of 20 km across on Europa after Pwyll based on ray preservation (e.g., Moore et al., 2001 Schenk & Turtle, 2009). Despite these limitations, the only known sets of these distinctive V-shaped en echelon fissures occur in association with the two crop circle patterns in the locations identified (Figure 2). Our knowledge of the global extent of these fissure sets is limited by the fragmentary and variable quality of the Voyager-Galileo image mapping (e.g., Schenk, 2010). Note that, at least until mosaic edge, fissure continues into and therefore postdates chaos material at top. This highest resolution low-Sun view of fissures shows the central and subsidiary flanking fissures, as well as rolling surfaces between and trending parallel to the fissures. Portion of Galileo high-resolution mosaic (a) and PC-DEM (b) of Menec Fossa fissures crossing the “smooth” gray band Libya Linea, with profile (c). High-resolution views of Europan fissures at Libya Linea. These fissure sets form arcuate groupings that track parallel to and ~100–350 km outside the previously identified TPW arcuate troughs (Schenk et al., 2008) (Figure 2) and ~1,500- to 1,600-km radial distance from their centers, indicating that they are a component of the TPW deformation pattern. These en echelon fissures (Figures 2- 4) form at least four major spatially associated sets up to 1,000 km long (and fragments of several others) of arcuate parallel structural features. Prockter & Patterson, 2009), suggesting that different deformational regimes prevail in the two structural types. This morphological and structural style differs from that of the much more linear, continuous, and elevated double ridges common to Europa (cf. These fissures occur in offset segments typically ~10 to 45 km in length that terminate and then pick up again in the same direction but offset as much as 25 km to the side, forming classic en echelon shear fracture patterns (Figures 2- 4). To the limits of available resolution, these fissures are sharp-edged and appear V-shaped in profile, with perhaps minor apparent amounts of mass wasting along the walls, implying formation by dilation of surface faults. Although mappable in only a limited number of images ( supporting information Table S1), these newly identified crop circle features are evident as surface gashes or fissures up to 2 km wide and up to 200 m deep (Figures 3- 5). Inspection of a new preliminary global three-color base map of Europa at 200 m/pixel ( supporting information Figure S2) has revealed additional TPW-related features on Europa (Figure 2 and supporting information Figure S3). 2 Newly Identified TPW Features on Europa Note that east longitude system is used throughout. Pwyll and Manannan (“P” and “M”) craters are at 25°S, 90☎ and 4°N, 120☎, respectively, and shown as two thin circles representing extent of their inner ejecta deposits. The folds at Astypalae Linea are located at 70°S 170☎. “AL” and “CL” are the two bright bands Agenor and Corrick Linea. The two large dots represent the geographic centers of the TPW circle patterns. Shaded areas are those where resolutions of >2 km/pixel preclude any identification of these features. Global map showing distribution of concentric features on Europa associated with true polar wander (modified from Schenk et al., 2008), including the labeled outer ring of fissures described here (small squares show locations of fissures shown in Figures 3- 5).
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