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).