Lobate Scarps Research Articles

Dating long thrust systems on Mercury: New clues on the thermal evolution of the planet

The global tectonics of Mercury is dominated by contractional features mainly represented by lobate scarps, high relief ridges, and wrinkle ridges. These structures are the expression of thrust faults and are linear or arcuate features widely distributed on Mercury. Locally, these structures are arranged in long systems characterized by a preferential orientation and non-random spatial distribution. In this work we identified five thrust systems, generally longer than 1000 ​km. They were named after the main structure or crater encompassed by the system as: Thakur, Victoria, Villa Lobos, Al-Hamadhani, and Enterprise. In order to gain clues about their formation, we dated them using the buffered crater counting technique, which can be applied to derive the ages of linear landforms such as faults, ridges and channels. To estimate the absolute age for the end of the thrust system’s activity, we applied both Le Feuvre and Wieczorek Production Function and Neukum Production Functions. Moreover, to further confirm the results obtained with the buffered crater counting method, the classic stratigraphic approach has been adopted, in which a faulted and an unfaulted craters were dated for each system. The results gave consistent ages and suggested that the most movements along major structures all over Mercury most likely ended at about 3.6–3.8 ​Ga. This gives new clues to better understand the tectonics of the planet and, therefore, its thermal evolution. Indeed, the early occurrence of tectonic activity in the planet’s history, well before than predicted by the thermophysical models, coupled with the orientation and spatial distribution of the thrust systems, suggests that other processes beside global contraction, like mantle downwelling or tidal despinning, could have contributed to the first stage of the planet’s history.

The Seismically Active Lobate Scarps and Coseismic Lunar Boulder Avalanches Triggered by 3 January 1975 (MW 4.1) Shallow Moonquake

AbstractOn 3 January 1975, the largest shallow moonquake (MW 4.1) occurred at Laue impact crater on the Moon. The fault responsible for the moonquake and origins of coseismic boulder avalanches are unknown. Our study reveals a set of previously unreported, seismically active, young lobate scarps near the epicenter. In addition, hundreds of boulder falls are observed on the interior walls of two impact craters on either side of the lobate scarps. The varying preservation levels and crater size‐frequency distributions of impact craters superimposed on the boulder falls indicate their episodic origins at 1.6 Ma and during the 1975 shallow moonquake. Our ground motion simulations confirm that the MW 4.1 moonquake along the lobate scarp at 1‐ to 5‐km focal depths produced strong ground shaking that triggered the boulder avalanches. Also, the fault slip along the Lorentz basin wall beneath the Laue crater floor produced the lobate scarps and the shallow moonquakes.

Evidence of thrust faulting and widespread contraction of Ceres

The surface of the dwarf planet Ceres is considered to be dominated by geological processes typical of small bodies or medium-sized icy bodies, such as impact cratering1,2; there are also features of putative cryovolcanic origin3 as well as those related to flow of near-surface ice4. Extensional features4–6 include regional linear troughs, fractures and pit chains, fractures associated with impact craters and with crater floors, and polygonal craters whose walls seem to be structurally controlled. However, no contractional features, which are related to thrust fault activity more typical of large silicate bodies7–11, have been described. Here we report the presence of scarps, ridges and fractures associated with thrust faults, tectonically raised terrains and thrusted craters—all contractional features. These structures closely resemble thrust-fault-related lobate scarps on Mercury7,8 and Mars9,10, albeit with lower displacement. They seem more abundant in high-latitude ancient terrains, perhaps owing to illumination effects that aid identification. The observed deformation implies that the crustal material is stronger than water ice but weaker than silicate rocks, consistent with our current knowledge of crustal composition12 and rheology13. These features suggest that large-scale contraction, possibly related to differentiation processes, occurred in the history of Ceres. Contractional features such as scarps, ridges and fractures from thrust faults are typical of large silicate bodies such as Mercury and Mars. Evidence for similar features on Ceres suggests the possibility of large-scale contraction on this icy body.

Evidence for recent and ancient faulting at Mare Frigoris and implications for lunar tectonic evolution

Nearside basin-related extensional tectonism on the Moon was thought to have ended by about 3.6 billion years ago and mare basin-localized contractional deformation ended by about 1.2 billion years ago. Lunar Reconnaissance Orbiter Camera (LROC) high resolution (50–200 cm/pixel) images show the Moon's surface in unprecedented detail and have enabled us to find many previously unidentified tectonic landforms, forcing a re-assessment of our views of tectonism in the maria. The morphology and stratigraphic relationships of these newly identified populations of tectonic landforms imply a more complex and longer-lasting history of deformation. We selected Mare Frigoris as an ideal location to perform a mapping survey where excellent imaging conditions, abundant tectonic landforms, and restricted mascon allow us to unravel the mare's tectonic evolution. Similar to previous surveys, we find that tectonism in the eastern portion of Mare Frigoris was controlled by ancient mascon induced flexure. In the western portion, however, we identify a parallel set of ancient compressional wrinkle ridges across the mare that is inconsistent with an origin by mare basin-centric mascon flexure or influence from the Mare Imbrium mascon. Instead, our results imply an ancient, regional, non-isotropic stress field over western Mare Frigoris. We also identify young wrinkle ridges and show that they have likely been active within the last 1 billion years, and some ridges as recently as within 40 million years. Finally, we identify a 300 km long series of lobate scarps coincident with one of the shallow moonquakes recorded during Apollo and use geodetic strain from the mapped global population of young lobate scarps to predict a level of seismicity consistent with the shallow moonquakes recorded during Apollo. In tandem with similarly young lobate scarps and small graben, as well as recorded shallow moonquakes, these young wrinkle ridges imply that some tectonism in and around Mare Frigoris has occurred in the geologically recent past and likely still continues today.

Structural modeling of lobate scarps in the NW margin of Argyre impact basin, Mars

Martian lobate scarps are prominent tectonic structures interpreted to be the topographic expression of large thrust faults generated under compression. Here, we present a structural modeling performed on three large lobate scarps (Ogygis Rupes, Bosporos Rupes and Phrixi Rupes) located in the heavily cratered highlands of Mars, specifically in Aonia Terra, between Thaumasia Montes and Argyre impact basin. These lobate scarps, formed in the Late Noachian/Early Hesperian, strike parallel to the edge of the Thaumasia Montes, and were generated by ESE-vergent thrust faults. Structural analysis of craters deformed by these lobate scarps gives minimum estimates for the faults slip of ∼1700–3100 m. We applied two structural methods in order to constrain the geometry of these thrust faults at depth, area balanced cross sections and forward mechanical dislocation modeling, obtaining a depth of faulting in this area between ∼18 and ∼45 km, and dip angles between 23° and 35°. These results are consistent with previous studies of lobate scarps on Mars. The depth of faulting gives an estimation of the depth of the brittle-ductile transition at the time of its formation giving a range of depth in which the state of the lithosphere change from brittle to ductile-dominated deformation. The heat flow values calculated from the obtained depths of the brittle–ductile transition range from 25 to 51 mW m−2. We show that the brittle-ductile transition depth in Aonia Terra is set in 18–27 km at a larger distance from the basin center, while it is deeper closer to the Argyre rim (∼33–45 km). This difference seems to indicate a thickening of the brittle domain under Argyre main rim with respect to the external area but, attending to regional geology and heat flow values calculated, this high value (∼33–45 km) might be an overestimation of the depth of faulting caused by the presence of the crater rim elevation before the formation of the lobate scarps.

Topographic Expressions of Large Thrust Faults on Mars.

On planets with little erosion, thrust faults produce broad, asymmetric, positive-relief, linear to arcuate ridges -often referred to as lobate scarps- that remain largely unaltered, such that their topographic expressions are a measure of the structural uplift caused by the displacement and associated country-rock deformation of the faults. Here we map and systematically assess the structural relief of 24 thrust faults across Mars to infer their growth behavior. Our mapping indicates that the majority of individual thrust faults have simple, linear map traces with lengths of up to ~450 km, but that some thrust faults form systems of up to 1400 km in length. For the most topographically pronounced landforms, the structural relief developed above the fault is as great as ~3400 m. We then relate topographic measurements to the displacement on the underlying fault planes to study the displacement variations along the fault length. We find a variety of displacement distribution shapes of the fault systems, which we attribute to differences in fault growth that include unrestricted and restricted growth, linkage, and/or fault interaction. Finally, we relate the maximum displacements (Dmax ) determined for each of the faults to their respective fault length (L) to establish a maximum displacement-to-length relationship. The observed scaling characteristics and order-of-magnitude scatter of our Dmax/L data are not uncommon for fault populations on Earth and tie in well with the map patterns, tectonic geomorphology, and systematic along-strike displacement distributions to have grown in a basement-block faulting style found in intra-plate tectonic settings on Earth.

Tectonic patterns of shortening landforms in Mercury's northern smooth plains

Mercury's northern smooth plains are volcanically emplaced units characterized by ghost craters, volcanically buried impact basins, and thrust fault-related landforms. We analyzed the thrust fault-related landforms, traditionally categorized as lobate scarps and wrinkle ridges, within the northern plains in order to describe trends in how these landforms are organized and oriented and what style of deformation (either thin or thick-skinned) their map patterns represent. Our analysis also establishes geologic constraints for which global processes may have produced stresses contributing to these tectonic patterns. We mapped 4853 thrust fault-related landforms in the northern plains at a map scale of 1:1,000,000 using three MErcury Surface, Space, ENvironment, GEochemistry, and Ranging (MESSENGER) global monochrome mosaics. These landforms, described as curvi-linear asymmetric ridges, frequently occur in complex geometrical arrangements that are interpreted to share similar structural characteristics. We called these arrangements “compound landforms”. Like prior studies, we observed thrust faults to follow rims of buried craters. We also observed (1) sigmoidal rises bounded by fault-related landforms, (2) V-shaped rises composed of two landforms terminating at a single sharp point, (3) broad arcuate rises of nearly equal width, (4) parallel, evenly-spaced ridges, and (5) landforms showing alternation in direction of tectonic transport along strike. Respectively, we interpreted these landforms as transpressional uplifts, faults with sharply juxtaposing ramps, pop-up structures, fold and thrust belts, and antithetic fault intersections. By comparison with Earth analogues and patterns produced in numerical and physical models, our results suggest that deformation in the NSPs is thin-skinned. Orientation analysis showed that the northernmost landforms (90°–70°N) were predominantly oriented east–west while most of the landforms between 50° and 30°N were oriented north–south. Variations in orientation with latitude indicate that the growth of thrust fault-related landforms was influenced by sources of stress other than global contraction. If reorientation of the pole due to the formation of the Caloris basin impact did occur, the pattern of fault orientations indicates that geologic processes producing the pattern operated after reorientation.

Timings of early crustal activity in southern highlands of Mars: Periods of crustal stretching and shortening

Extensional and compressional structures are globally abundant on Mars. Distribution of these structures and their ages constrain the crustal stress state and tectonic evolution of the planet. Here in this paper, we report on our investigation over the distribution of the tectonic structures and timings of the associated stress fields from the Noachis-Sabaea region. Thereafter, we hypothesize possible origins in relation to the internal/external processes through detailed morphostructural mapping. In doing so, we have extracted the absolute model ages of these linear tectonic structures using crater size-frequency distribution measurements, buffered crater counting in particular. The estimated ages indicate that the tectonic structures are younger than the mega impacts events (especially Hellas) and instead they reveal two dominant phases of interior dynamics prevailing on the southern highlands, firstly the extensional phase terminating around 3.8 Ga forming grabens and then compressional phase around 3.5–3.6 Ga producing wrinkle ridges and lobate scarps. These derived absolute model ages of the grabens exhibit the age ca. 100 Ma younger than the previously documented end of the global extensional phase. The following compressional activity corresponds to the peak of global contraction period in Early Hesperian. Therefore, we conclude that the planet wide heat loss mechanism, involving crustal stretching coupled with gravitationally driven relaxation (i.e., lithospheric mobility) resulted in the extensional structures around Late Noachian (around 3.8 Ga). Lately cooling related global contraction generated compressional stress ensuing shortening of the upper crust of the southern highlands at the Early Hesperian period (around 3.5–3.6 Ga).

Morphometric analysis of a Hesperian aged Martian lobate scarp using high-resolution data

Southern highlands of Mars have experienced regional to global scale deformations in the history of its evolution. Deformational structures originated from impact-induced stresses and later viscous relaxation of the impact basin to cooling related global contraction. Here in this study, we investigated an Early Hesperian (Eo-Archean / Paleo-Archean equivalent to the Earth) aged lobate scarp i.e., surface signature of thrust fault, possibly originated because of global contraction. We used ‘offset crater perimeter’ measurement technique using high-resolution data (both image and DTM) to execute most precise estimation of fault plane slope and length–displacement relationship. The derived range of fault plane slope is much narrower (21°–29°) than the previously cited 20° to 35° range. Displacement–length ratio (4.51 × 10−3) is also unique and lower than the previously evaluated values of lobate scarps from other region (mainly from dichotomy boundary) of Mars. The newly derived results from the morphometric analysis are due the differential stress pattern and the distinct basement rock rheology. Our results highlight the need for more high-resolution estimation of lobate scarps from several regions with the methodology employed in this study to better understand the global Martian early tectonic scenario.

How old are lunar lobate scarps? 1. Seismic resetting of crater size-frequency distributions

Previous studies have estimated the ages of lunar lobate scarps, some of the youngest tectonic landforms on the Moon, based on the estimated life-times of their fresh morphologies and associated small graben, using crater degradation ages, or via buffered and traditional crater size-frequency distribution (CSFD) measurements. Here, we reexamine five scarps previously dated by Binder and Gunga (1985) with crater degradation ages to benchmark the evaluation of both the buffered and traditional CSFD approaches for determination of absolute model ages (AMAs) at scarps. Both CSFD methods yield similar ages for each individual scarp, indicating that fault activity not only can be measured on the scarp itself, but also in the surrounding terrain – an indication that tectonic activity causes surface renewal both adjacent to and even kilometers distant from scarps. Size-frequency variations in the regions surrounding the scarps are thus useful for studying the extent and severity of the ground motion caused by coseismic slip events during scarp formation. All age determination approaches continue to indicate that lunar lobate scarps were active in the late Copernican, with some scarps possibly experiencing activity within the last 100 Ma.

Investigation of newly discovered lobate scarps: Implications for the tectonic and thermal evolution of the Moon

Using observations of lunar scarps in Apollo Panoramic Camera photos, Binder and Gunga (1985) tested competing models for the initial thermal state of the Moon, i.e., whether it was initially completely molten or if the molten portion was limited to a global magma ocean. Binder and Gunga (1985) favored the concept of an initially molten Moon that had entered into a late-stage epoch of global tectonism. Since the start of the Lunar Reconnaissance Orbiter mission, thousands of new small lobate scarps have been identified across the lunar surface with high-resolution images from the Lunar Reconnaissance Orbiter Camera (LROC). As such, we selected spatially random scarps and reevaluated the fault dynamical calculations presented by Binder and Gunga (1985). Additionally, we examined the geometry and properties of these fault scarps and place better constraints on the amount of scarp-related crustal shortening. We found that these low angle thrust faults (∼23˚) have an average relief of ∼40 m and average depths of 951 m. Using crater size-frequency distribution (CSFD) measurements, we derived absolute model ages for the scarp surfaces proximal to the trace of the fault and found that the last slip event occurred in the last ∼132 Ma. Along with young model ages, lunar lobate scarps exhibit a youthful appearance with their crisp morphologies which is indicative of late-stage horizontal shortening. In conclusion, interior secular cooling and tidal stresses cause global contraction of the Moon.

Small graben in the southeastern ejecta blanket of the lunar Copernicus crater: Implications for recent shallow igneous intrusion on the Moon

Dozens of linear graben that are about 10–400m wide and less than 1km long are recognized in the southeastern continuous ejecta deposits of Copernicus, supporting that Copernican-aged tectonism has occurred on the Moon. Fault geometry analysis suggests that the bounding faults of the graben have formed within the ejecta deposits. The graben are exclusively located on a local high-relief area, but they are not formed by mass wasting, because the topographic slope is substantially less than the repose angle of typical lunar materials, and no other extensional structures are visible on similar high-relief areas at the continuous ejecta deposits of Copernicus. The orientations of the graben all point to the center of Copernicus, but the topography of Copernicus is little compensated after formation, suggesting that the graben were not caused by possible crustal isostatic readjustment. This graben system is one of the three examples on the Moon that were interpreted to be caused by shallow igneous intrusions in the format of laccoliths. The currently available GRAIL gravity data have a lower spatial resolution than the size of the graben, so the gravity data cannot resolve the hypothesized sub-kilometer-scale laccoliths beneath the graben. While laccolith intrusion to a depth of about 80m is required to explain the formation of this graben system, the laccolith intrusion scenario is not consistent with the geological context of the graben. A compressional structure is visible close to the graben system, and their spatial configuration and similar preservation states are consistent with being generically related. A close examination of the other two sets of graben that were also interpreted to have no associated compressional structures actually reveals spatially-related lobate scarps and wrinkle ridges in the vicinity. Therefore, shallow igneous intrusion is not plausible or necessary to explain to formation of Copernican-aged graben on the Moon, and they are most likely formed by the late-stage global contraction of the Moon.

Late movement of basin-edge lobate scarps on Mercury

Basin-edge lobate scarps are a sub-type of tectonic shortening structure on the surface of Mercury that have formed at the edge of volcanic units that fill or partly fill impact basins. We have performed a global survey of these features and find that they are widespread in basins across the planet. We obtained model ages from crater size–frequency distribution analysis for a subset of our surveyed basins, for both the smooth plains infill and for the last resolvable tectonic activity on the associated basin-edge scarps. Our results indicate that some of these lobate scarps were still accumulating strain in the late Mansurian (approximately 1Ga). From a photogeological assessment, we find that the orientations of these basin-edge lobate scarps are similar to those reported for the global population of lobate scarps in earlier studies, appearing to align ∼north–south at low latitudes and ∼east–west at higher latitudes. However, reassessing these landforms’ orientation with artificially illuminated topographic data does not allow us to rule out the effect of illumination bias. We propose that these landforms, the result of crustal shortening in response to global contraction, formed along the interface between the basin floor and the smooth plains unit, which acted as a mechanical discontinuity along which shortening strains were concentrated.

Thrust fault modeling and Late-Noachian lithospheric structure of the circum-Hellas region, Mars

The circum-Hellas area of Mars borders Hellas Planitia, a giant impact ∼4.0–4.2Ga old making the deepest and broadest depression on Mars, and is characterized by a complex pattern of fracture sets, lobate scarps, grabens, and volcanic plains. The numerous lobate scarps in the circum-Hellas region mainly formed in the Late Noachian and, except Amenthes Rupes, have been scarcely studied. In this work, we study the mechanical behavior and thermal structure of the crust in the circum-Hellas region at the time of lobate scarp formation, through the modeling of the depth of faulting beneath several prominent lobate scarps. We obtain faulting depths between ∼13 and 38km, depending on the lobate scarp and accounting for uncertainty. These results indicate low surface and mantle heat flows in Noachian to Early Hesperian times, in agreement with heat flow estimates derived from lithospheric strength for several regions of similar age on Mars. Also, faulting depth and associate heat flows are not dependent of the local crustal thickness, which supports a stratified crust in the circum-Hellas region, with heat-producing elements concentrated in an upper layer that is thinner than the whole crust.

Recent tectonic activity on Mercury revealed by small thrust fault scarps

The planet Mercury has contracted over its history. The identification of small thrust fault scarps suggests the occurrence of tectonic activity on Mercury within the past 50 million years and thus a slow-cooling planetary interior. Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s1. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet’s past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long2,3,4,5. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon6,7,8. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet’s interior.

Recent shallow moonquake and impact-triggered boulder falls on the Moon: New insights from the Schrödinger basin

Shallow moonquakes are thought to be of tectonic origin. However, the geologic structures responsible for these moonquakes are unknown. Here we report sites where moonquakes possibly occurred along young lobate scarps in the Schrodinger basin. Our analysis of Lunar Reconnaissance Orbiter and Chandrayaan-1 images revealed four lobate scarps in different parts of the Schrodinger basin. The scarps crosscut small fresh impact craters ( 1500 boulders associated with trails and bouncing marks. Their origins are largely controlled by recent impact events. Ejecta rays and secondary crater chains from a 14 km diameter impact crater traversed Schrodinger and triggered significant boulder falls about 17 Ma. Therefore, a combination of recent shallow moonquakes and impact events triggered the boulder falls in the Schrodinger basin.

Duration of activity on lobate‐scarp thrust faults on Mercury

Lobate scarps, landforms interpreted as the surface manifestation of thrust faults, are widely distributed across Mercury and preserve a record of its history of crustal deformation. Their formation is primarily attributed to the accommodation of horizontal shortening of Mercury's lithosphere in response to cooling and contraction of the planet's interior. Analyses of images acquired by the Mariner 10 and MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft during flybys of Mercury showed that thrust faults were active at least as far back in time as near the end of emplacement of the largest expanses of smooth plains. However, the full temporal extent of thrust fault activity on Mercury, particularly the duration of this activity following smooth plains emplacement, remained poorly constrained. Orbital images from the MESSENGER spacecraft reveal previously unrecognized stratigraphic relations between lobate scarps and impact craters of differing ages and degradation states. Analysis of these stratigraphic relations indicates that contraction has been a widespread and long-lived process on the surface of Mercury. Thrust fault activity had initiated by a time near the end of the late heavy bombardment of the inner solar system and continued through much or all of Mercury's subsequent history. Such deformation likely resulted from the continuing secular cooling of Mercury's interior.

Global thrust faulting on the Moon and the influence of tidal stresses

Lunar Reconnaissance Orbiter Camera images reveal a vast, globally distributed network of over 3200 lobate thrust fault scarps, making them the most common tectonic landform on the Moon. Based on their small scale and crisp appearance, crosscutting relations with small-diameter impact craters, and rates of infilling of associated small, shallow graben, these fault scarps are estimated to be younger than 50 Ma and may be actively forming today. The non-random distribution of the scarp orientations is inconsistent with isotropic stresses from late-stage global contraction as the sole source of stress. We propose that tidal stresses contribute significantly to the current stress state of the lunar crust. Orbital recession stresses superimposed on stresses from global contraction with the addition of diurnal tidal stresses result in non-isotropic compressional stress and thrust faults consistent with lobate scarp orientations. The addition of diurnal tidal stresses at apogee result in peak stresses that may help trigger coseismic slip events on currently active thrust faults on the Moon.

Identification of tectonic deformations on the south polar surface of the moon

Recent extensional and contractional tectonic features present globally over the lunar surface have been studied to infer lunar crustal tectonism. Investigation of indicators of recent crustal tectonics, such as fault lines, thrust fault scarps, and dislocation of debris along the identified fault planes, primarily using data from the miniature-synthetic aperture radar (mini-SAR) aboard CHANDRAYAAN-1 mission and Narrow angle camera (NAC) images, are the focus of this study. Spatial orientation of these tectonic features helps to elucidate the change in the interior geological dynamics of any planetary body with time. The ability of microwave sensors to penetrate the lunar regolith, along with application of m-χ decomposition method on Mini-SAR data has been used to reveal unique features indicative of hidden tectonics. The m-χ decomposition derived radar images expose hidden lineaments and lobate scarps present within shadowed crater floors as well as over the illuminated regions of the lunar surface. The area around and within Cabeus B crater in the South Polar Region contains lobate scarps, hidden lineaments and debris avalanches (associated with the identified lineaments) indicative of relatively recent crustal tectonism.

Evidence for two stages of compressive deformation in a buried basin of Mercury

The surface of Mercury shows abundant compressive tectonic landforms, including lobate scarps, wrinkle ridges and high-relief ridges, which are different manifestations of thrust faults, and long-wavelength topography variations, which could be the expression of large scale folding. These landforms probably relate to planetary cooling, although other factors such as mantle convection, tidal despinning or true polar wander could affect the distribution, expression and orientation patterns of compressive features. In this work we show that an area of smooth plains including a buried ∼500-km-diameter impact basin experienced two different stages of deformation. The younger deformation stage is characterized by a set of NW–SE oriented wrinkle ridges affecting the smooth plains and having the same approximate orientation as the wrinkle ridges and lobate scarps deforming the surrounding terrains. The older set of tectonic structures consists of NE–SW oriented, closely spaced, subparallel, quasi-rectilinear and low-relief ridges, partially buried by the smooth plains material and crossed by the wrinkle ridges. Therefore, our results suggest that several events occurred between both deformation stages: at least one stage of basin filling; a change in stress orientation, an increasing in the wavelength and amplitude of deformation, and maybe an increasing of the thickness of the deformed layer. Our observations imply a complex stress history for compressive deformation, maybe influenced by the internal and/or orbital/rotational history of Mercury, and are illustrative of the complexity of tectonic history likely to have affected many or most other regions of the planet.