Figure 1 . Schematic model of the signs of recent tectonic activity. A small crisp wrinkle ridge segment in Mare Tranquillitatis served as a template for the topographic profile. The signs of recent tectonic activity apply, however, both for lobate scarps and wrinkle ridges. These signs include crisp morphology, deformed craters, cross-cut craters, small graben and troughs, lower crater density, and boulder fields/patches. In this study, the boulder abundance was not used to determine the degradational stage of a wrinkle ridge or lobate scarp.
Figure 2 . Location of Mare Tranquillitatis (black outline) near the lunar equator projected onto the global merged LRO LOLA – SELENE Kaguya DEM (Barker et al., 2016).
Figure 3 . Tectonic map of Mare Tranquillitatis projected on the merged LRO LOLA – SELENE Kaguya DEM (Barker et al., 2016). Parts of the lobate scarp cluster in the northern mare cross the highland boundary and continue into Mare Serenitatis near the Taurus-Littrow valley. Unidentified features are linear positive topographic features with a possible but unproven tectonic origin (other possible origins are, e.g., dikes, lava flows, surface expressions of buried structures, or ejecta remnants).
Figure 4 . Tectonic feature map with all degradational classified segments colorized according to their respective class and projected onto the WAC global mosaic (Robinson et al., 2012). Tectonic features in the western part are mostly comprised of advanced and heavily degraded features. Crisp and degraded features occur scattered in clusters throughout the mare.
Figure 5 . NAC images of crisp features. White arrows show representative graben. a) Wrinkle ridge north of Ross Crater with a crisp morphology and small graben (M1184668142RE; 11.82°N, 24.27°E). b) Image of the same wrinkle ridge further west. Visible are several sets of small graben and a small boulder patch (black arrow; M1184668142RE; 11.90°N, 24.17°E). c) Small and faint lobate scarp in the vicinity of Taurus-Littrow valley. The image shows some faint graben-like features and deformed craters with ~100 to ~50 m in diameter (black arrows; M1154023134RE; 19.11°N, 29.93°E). d) Set of graben in close vicinity of a crisp lobate scarp cluster near Taurus-Littrow (M1157549836RE; 18.52°N, 30.55°E).
Figure 6 . NAC images of degraded features with relatively sharp contacts (white arrows) in Mare Tranquillitatis. a) A degraded wrinkle ridge in the eastern mare deforming and cross-cutting several craters (black arrows; M1245756057LE/RE; 12.29°N, 39.82°E) and b) a small degraded lobate scarp in the northwestern mare which also deforms a ~100 m diameter crater (black arrows; M1279976340LE; 14.60°N, 20.04°E).
Figure 7 . Kaguya Terrain Camera images of a representative advanced (a) and heavily (b) degraded wrinkle ridge (white arrows). The advanced degraded wrinkle ridge (7.54°N, 22.75°E) has a well-developed wrinkle ridge morphology consisting of a broad arch and a superimposed ridge (white arrows). In addition, it exhibits several dominant boulder fields, which are visible as bright spots along the ridge (black arrows). The morphology of the heavily degraded wrinkle ridge (b) is less distinctive and the typical wrinkle ridge morphology is less well-developed (1.31°N, 22.56°E).
Figure 8 . Bouguer anomaly map of Tranquillitatis superposed on the WAC global mosaic. The map has the same spatial extent as the maps in Fig. 3 and 4. The outline of Mare Tranquillitatis is shown as a fine white line. Yellowish colors indicate positive gravitational anomalies, which implies a thin crust and mantle upwelling, as well as a thick abundance of basalt. Mascon basins like Mare Serenitatis in the northwestern part of the map are represented in yellow colors, whereas non-mascon basins like Mare Tranquillitatis appear in more heterogenous and mainly blue and green colors. The western part of Mare Tranquillitatis has more pronounced positive gravitational anomalies than the eastern part. Concentric wrinkle ridges occur at the positive Lamont anomaly in southwestern Tranquillitatis. Tectonic features in the western part are mostly comprised of advanced and heavily degraded features. Crisp and degraded features occur scattered throughout the mare. Features in eastern Tranquillitatis seem to be uncorrelated to gravity anomalies. Crisp and degraded features are also not correlated with gravitational anomalies.
Figure 9 . Rose diagram of the orientations of crisp features within Mare Tranquillitatis. Crips features share a western to northwestern orientation.
Figure 10 . Evidence for more recent activity by ancient wrinkle ridges in Mare Tranquillitatis. (a) Shows the topographic map of the region southeast of the Lamont anomaly. The stars mark the locations of (b) and (c). (b) Shows NAC image (M1108125194LE; 3.43°N, 23.97°E) showing a part of a concentric wrinkle ridge at the southeastern Lamont anomaly. It crosscuts craters with ~100 m in diameter (white arrow) and exhibits several boulder fields (black arrows). (c) NAC image (M162134363LE) of faint graben-like features on the hanging wall of a wrinkle ridge (0.45°S, 26.47°E).