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Publications
Publications (349)
The Moon’s lithosphere has been in a net compressional stress regime for the past 3.6 billion years, leading to the formation of globally distributed kilometer-scale thrust faults that form lobate scarps at the surface. Lobate scarps are among the youngest features on the lunar surface. A sign of their recent activity is the presence of meter-scale...
The timing and scale of lunar tectonism provide a crucial insight into the geologic evolution of Earth’s Moon. Within the nearside lunar maria, wrinkle ridges formed during and after the emplacement of the mare basalts as a result of subsidence-induced contraction. Past analyses of lunar wrinkle ridges and associated fault structures have helped to...
Wrinkle ridges are the predominant tectonic structure on the nearside lunar maria. Although lunar wrinkle ridge formation began as early as ∼3.9–4.0 Ga, recent investigations have identified wrinkle ridges in the lunar maria that were tectonically active as recently as the Copernican period of lunar geologic history. Some of those geologically youn...
We just finished the 5th quadrangle for “MerCatSS” — the Mercury Catalog of Shortening Structures. We produced a global 222 m/pixel DTM allowing us to catalog 15, mostly unprecedented morphometric parameters for each mapped structure.
To assess the temporal trends of scarp parameters and to better understand global/regional stress, we will determine both relative and absolute ages for the shortening structures in the western hemisphere of Mercury.
The lunar south pole regions are subjected to global stresses that result in contractional deformation and associated seismicity. This deformation is mainly expressed by lobate thrust fault scarps; examples are globally distributed, including polar regions. One small cluster of lobate scarps falls within the de Gerlache Rim 2 Artemis III candidate...
Subsurface reflectors in radar sounder data from the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express spacecraft indicate significant dielectric contrasts between layers in the Martian Medusae Fossae Formation (MFF). Large density changes that create dielectric contrasts are less likely in deposits of v...
In the work presented here, we build on prior age determination studies for young wrinkle ridges on the Moon by conducting traditional and buffered crater counts over a recently active wrinkle ridge in eastern Mare Procellarum.
The lithosphere of the Moon has been deformed by tectonic processes for at least 4 billion years, resulting in a variety of tectonic surface features. Extensional large lunar graben formed during an early phase of net thermal expansion before 3.6 Ga. With the emplacement of mare basalts at ∼3.9–4.0 Ga, faulting and folding of the mare basalts initi...
The lithosphere of the Moon has been deformed by tectonic processes for at least 4 billion years, resulting in a variety of tectonic surface features. Extensional large lunar graben formed during an early phase of net thermal expansion before 3.6 Ga. With the emplacement of mare basalts at ~3.9 – 4.0 Ga, faulting and folding of the mare basalts ini...
We provide the first solar system wide compendium of speleogenic processes and products. An examination of 15 solar system bodies revealed that six cave‐forming processes occur beyond Earth including volcanic (cryo and magmatic), fracturing (tectonic and impact melt), dissolution, sublimation, suffusion, and landslides. Although no caves (i.e., con...
Introduction: The global distribution of shortening structures on Mercury as well as geographic and temporal trends of any of their morphometric and structural parameters are key to better understand the planets' history of contraction, tidal despinning, and lithologic/rheologic variations in its current crust [1-4]. Previous global cataloging of~6...
Evidence of significant extension on the Moon is associated with nearside mare. The load induced by the mare basalts resulted in lithospheric flexure and graben forming extension. We use high-resolution topographic and image data from the Lunar Reconnaissance Orbiter (LRO) and the SELenological and ENngineering Explorer (SELENE) to generate detaile...
Wrinkle ridges are the largest and most morphologically complex contractional landforms found on the Moon. They occur exclusively in mare basalt and are thought to result from load induced subsidence and flexure of the lunar lithosphere. The displacement‐length (Dmax/L) relations of wrinkle ridge thrust faults in mascons, where mare basalts are gen...
The Lunar Geophysical Network (LGN) mission is proposed to land on the Moon in 2030 and deploy packages at four locations to enable geophysical measurements for 6–10 yr. Returning to the lunar surface with a long-lived geophysical network is a key next step to advance lunar and planetary science. LGN will greatly expand our primarily Apollo-based k...
The crust of Mercury has experienced contraction on a global scale. Contractional deformation is expressed by a broadly distributed network of lobate thrust fault scarps. The most likely principal source of stress is global contraction from cooling of Mercury's interior. Global contraction alone would be expected to result in a uniformly distribute...
The Lunar Geophysical Network (LGN) mission is proposed to land on the Moon in 2030 and deploy packages at four locations to enable geophysical measurements for 6-10 years. Returning to the lunar surface with a long-lived geophysical network is a key next step to advance lunar and planetary science. LGN will greatly expand our primarily Apollo-base...
The extensive Medusae Fossae Formation (MFF) along the dichotomy boundary on Mars has geologic features indicative of wind erosion of low‐density material. There is evidence suggesting a water ice component, but with considerable uncertainty linked to the unknown MFF porosity and compaction behavior. We use SHARAD radar sounder data to estimate the...
Mercury is a one-plate planet that has experienced significant radial contraction primarily driven by interior cooling. In some previous studies aimed at estimating the total magnitude of contraction, numerous faults are assigned to positive relief landforms, many without evidence of origin by deformation, resulting in estimates of planetary radius...
Rationale for the deployment of a Lunar Geophysical Network (LGN) in 2030.
Planetary tectonics provide a record of the myriad of processes that shape planetary surfaces and interiors. While there is a long history of mapping and modeling planetary tectonics, stresses from disparate processes are not generally captured by a single model. We present a comprehensive and general stress and tectonics model that can consider mu...
Graben are a common tectonic landform associated with lunar mare. These graben are hypothesized to have formed either due to subsidence induced flexure resulting from loading of the lithosphere by mare basalt (mascon tectonics) or by dikes related to intrusive volcanism. High-resolution topography derived from data from the Lunar Reconnaissance Orb...
In 2007, the National Academies designated “understanding the structure & composition of the lunar interior” (to provide fundamental information on the evolution of a differentiated planetary body) as the second highest lunar science priority that needed to be addressed. Here we present the current status of the planned response of the Lunar Geophy...
Block fields and associated relatively high reflectance material along wrinkle ridge summits are revealed in meter‐scale Lunar Reconnaissance Orbiter Camera images. Wrinkle ridges with block fields in Mare Australe, Crisium, Fecunditatis, Frigoris, Nubium, the northern half of Oceanus Procellarum, Serenitatis, and Tranquillitatis are evenly distrib...
Found on all terrestrial planets, wrinkle ridges are anticlines formed by thrust faulting and folding resulting from crustal shortening. The MErcury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft's orbital phase returned high resolution images and topographic data of the previously unimaged northern high latitudes of M...
The discovery of young thrust faults on the Moon is evidence of recent tectonic activity, but how recent is unknown. Seismometers at four Apollo landing sites recorded 28 shallow moonquakes between 1969 and 1977. Some of these shallow quakes could be associated with activity on the young faults. However, the epicentre locations of these quakes are...
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 enable...
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 fiv...
Meridiani Planum is one of the most intensely studied regions on Mars, yet little is known about the physical properties of the deposits below those examined by the Opportunity rover. We report the detection of subsurface echoes within the Meridiani Planum deposits from data obtained by the Mars Advanced Radar for Subsurface and Ionospheric Soundin...
We selected approximately 10,500 narrow-angle camera (NAC) and wide-angle camera (WAC) images of Mercury acquired from orbit by MESSENGER's Mercury Dual Imaging System (MDIS) with an average resolution of 150 m/pixel to compute a digital terrain model (DTM) for the H6 (Kuiper) quadrangle, which extends from 22.5°S to 22.5°N and from 288.0°E to 360....
The Rembrandt basin is crosscut by the largest fault scarp on Mercury, Enterprise Rupes, and a second scarp complex, Belgica Rupes, extends to the basin's rim. Topographic data derived from MESSENGER orbital stereo images show that these tectonic landforms bound a broad, relatively flat-floored valley with a mean width of ~400 km. Crosscutting rela...
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-1970s. 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 contr...
Subsurface radar sounding observations by the MARSIS and SHARAD instruments are affected by ionospheric phase distortions that lead to image blurring and delay offsets. Based on experience with SHARAD image correction, we propose that ionospheric blurring in MARSIS radargrams may be compensated with a model of smoothly varying quadratic phase error...
To date, no detailed fracture mapping of the wispy terrains of Saturn’s moon Dione have been completed in conjunction with a detailed characterization of the tectonic structures. Our analysis of the structures within Dione’s wispy terrains reveals tectonic features identified as scarps, twin scarps (likely graben), and troughs. Along with being les...
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 gra...
The Lunar Reconnaissance Orbiter Camera (LROC) is the first instrument to provide widespread coverage with a range of incidence angles at the resolution required to detect small-scale landforms. A sample (n = 238) of globally distributed, small-scale graben average 26 m wide and 179 m long. When dividing the population into those located within mar...
The surface of Mercury is dominated by contractional tectonic landforms that are evidence of global-scale crustal deformation. Using MESSENGER orbital high-incidence angle imaging and topographic data, large-scale lobate thrust fault scarps have been mapped globally. The spatial distribution and areal density of the contractional landforms are not...
Caloris basin, Mercury's youngest large impact basin, is filled by volcanic plains that are spectrally distinct from surrounding material. Post-plains impact craters of a variety of sizes populate the basin interior, and the spectra of the material they have excavated enable the thickness of the volcanic fill to be estimated and reveal the nature o...
Mars Express, the first European interplanetary mission, carries the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) to search for ice and water in the Martian subsurface. Developed by an Italian–US team, MARSIS transmits low-frequency, wide-band radio pulses penetrating below the surface and reflected by dielectric discontinuit...
Mercury, a planet with a lithosphere that forms a single tectonic plate, is replete with tectonic structures interpreted to be the result of planetary cooling and contraction. However, the amount of global contraction inferred from spacecraft images has been far lower than that predicted by models of the thermal evolution of the planet's interior....
Digital mapping of lunar mare and lobate scarps.
Global contraction / Of Mercury is more than / Recognized before.
Subsurface reflectors in the Meridiani Planum plains deposits detected by the MARSIS radar sounder.
LROC images and GRAIL gravity data provide new insights into the complex tectonic history of Mare Frigoris, including recent deformation in the basin.
Boulders and high reflectance material along wrinkle ridge slopes may be related to seismic activity from impacts and recent tectonic activity.
The distribution of young thrust fault scarps on the Moon may be the result of global contraction in combination with tidal stresses.
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 i...
We assess the geographic relationship between faults and crustal thickness on Mercury. We find potential for influence of mantle flow on scarp localization.
[1] The volcanic plains that fill the Caloris basin, the largest recognized impact basin on Mercury, are deformed by many graben and wrinkle ridges, among which the multitude of radial graben of Pantheon Fossae allow us to resolve variations in the depth extent of associated faulting. Displacement profiles and displacement-to-length scaling both in...
Orbital images from the MESSENGER spacecraft show that ~27% of Mercury's
surface is covered by smooth plains, the majority (>65%) of which are
interpreted to be volcanic in origin. Most smooth plains share the
spectral characteristics of Mercury's northern smooth plains, suggesting
they also share their magnesian alkali-basalt-like composition. A
s...
Extensional tectonic deformation on Mercury is almost entirely
restricted to impact features that host volcanic smooth plains. However,
tectonic landforms within such features vary enormously in structural
complexity. Here, we describe the progression in tectonic complexity
within four representative volcanically flooded impact sites — a
"ghost cra...
We present evidence for the volcanic origin of a region of intercrater
plains associated with an ancient impact basin approximately the same
size as Caloris.
The frequent spatial association of volcanic pits with thrust faults on
Mercury is motivation to study if faults functioned as conduits for
volatile-rich magmas.
We describe the progression in tectonic complexity from some of the
smallest to the largest volcanically infilled impact features on
Mercury.
MESSENGER orbital images and topographic data are used to map prominent
lobate scarps and characterize the globally contractional strain on
Mercury.
We show that the Caloris interior plains are at least 2.5 km thick, were
emplaced within a short interval, and predated the large-scale tectonic
modification.
We compare maps of lobate scarps and high-relief ridges to crustal
thickness on Mercury, and find no preferred crustal thickness values for
their localization.
We are digitizing lobate scarps in a GIS to identify, age date, and
understand the spatial distribution of these tectonic features, using
LROC and LOLA data.
We examine SHARAD radargrams for layers in the basal unit of Planum
Boreum at Mars' north pole.
A broad valley flanked by lobate scarps associated with the Rembrandt
basin may be evidence of long-wavelength deformation of Mercury’s
lithosphere.
Morphometric comparison of 300 mercurian and lunar wrinkle ridges
indicate greater amounts of global contraction on Mercury than the Moon.
Tectonic deformation within Mare Frigoris has continued to within the
last tens of millions of years.
Revised displacement-length relationship of thrust faults associated
with lobate scarps on the Moon using data from the Lunar Reconnaissance
Orbiter.
Before the launch of the Lunar Reconnaissance Orbiter, known
characteristics of lobate scarps on the Moon were limited to studies of
only a few dozen scarps revealed in Apollo-era photographs within
~20° of the equator. The Lunar Reconnaissance Orbiter Camera now
provides meter-scale images of more than 100 lobate scarps, as well as
stereo-derived...