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Publications (236)
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We identify a large fault system, called a shortening structure, that has been repeatedly active during the last 2 billion years. This is suggested by a series of landslides with a variety of degradation states. These originate from where a large‐scale shortening structure deforms the wall of Marsabit crater. We propose these...
The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be comp...
Mercury’s Debussy Quadrangle (H14) lies between 0–90° E and 22.5–65° S. Here we use MESSENGER data to produce the first geological map of this quadrangle at a scale of 1:3,000,000, based on linework completed at a scale of 1:300,000. We distinguish crater units and plains units. For compatibility with historic and recent maps of other Mercury quadr...
Mercury's tectonic history has been dominated by global contraction as the planet shrinks and cools. Previously, fault dips have been indirectly estimated by measuring offsets to the rims of craters displaced by fault movement. Here we present the first observations of a fault surface exposed in three dimensions, in this case within a volcanic vent...
Explosive volcanic vents are widespread on Mercury. Compound volcanic vents comprise multiple individual vents, and probably formed through multiple events. We demonstrate that ~70% of the volcanic vent sites on Mercury that have been imaged with sufficient resolution to resolve their internal features are compound vents that have probably undergon...
Our tectonic mapping as part of a larger morphostratigraphic mapping effort of the H13, Neruda Quadrangle has led us to recognise the “Neruda-Paramour-Alvin” thrust system. The system appears to extend from the southern limits of H13 north through H09 and H08 and simplifies at its northern end in H04. Mercury’s tectonic evolution is dominated by gl...
The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be comp...
Geological Mapping Update
Mapping update and volcanic vent discovery
The Hokusai (H05) quadrangle is in Mercury’s northern mid-latitudes (0–90°E, 22.5–65°N) and covers almost 5 million km2, or 6.5%, of the planet’s surface. We have used data from the MESSENGER spacecraft to make the first geological map of H05. Linework was digitized at 1:400,000-scale for final presentation at 1:3,000,000-scale, mainly using a ~166...
A complete global series of 1:3M-scale maps of Mercury is being prepared in support to the ESA/JAXA BepiColombo mission. Currently, 35% of Mercury has been mapped and 55% of the planet will be covered soon by the maps in progress.
Observations based on an average mapping scale of 1:400k provide context for the redefinition of the global stratigraphy of Mercury. Results show that the Intermediate Plains unit should be re-introduced as an official mappable terrain.
After the end of Mariner 10 mission a 1:5M geologic map of seven of the fifteen quadrangles of Mercury [Spudis and Guest, 1988] was produced. The NASA MESSENGER mission filled the gap by imaging 100% of the planet with a global average resolution of 200 m/pixel and this led to the production of a global 1:15M geologic map of the planet [Prockter et...
We are looking for geological evidence for volcanism in Mansurian impact basins (>100 km). This will tell us about how plains volcanism ended on Mercury during an era of global cooling and contraction. Within the Mansurian, we predict that older, larger basins host more volcanism than younger, smaller ones. We expect there came a time when impacts...
We are using MESSENGER data to produce a 1:3M scale geological map of the Hokusai (H05) quadrangle. Linework is drawn at 1:400k. Below, we show the current state of the map. Mapping of the northern smooth plains is nearly complete. Next, we will map the intercrater plains in the south. We will consider subdivision of this more cratered unit into tw...
The smooth plains on the floor of Mercury's Caloris basin and those almost entirely surrounding it beyond its rim are usually accepted to be younger than the rim materials, and to be lava flows rather than impact melt. High resolution imaging shows that emplacement of interior and exterior plains was concurrent, with evidence of both inward and out...
MESSENGER data are being used to construct ~1:3M scale quadrangle geological maps of Mercury. Here, we present our progress mapping the Hokusai quadrangle.
The globally extensive smooth plains of Mercury are believed to be mostly volcanic in origin. Widespread effusive volcanism on Mercury is thought to have ended by ~3.5 Ga due to secular cooling of the planet’s interior, and contraction of its lithosphere. As the planet cools and contracts, melt should be produced at a slower rate and in smaller vol...
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...
Small (<50 km across) shield volcanoes are known on Earth, the Moon, Mars and Venus, but previous identifications of these features on Mercury have been reevaluated. Until now, only low-lying volcanic craters formed by putative explosive eruptions have been positively identified on Mercury. We have found two new candidate small shields at the edges...
Mercury’s quadrangle H02 ‘Victoria’ is located in the planet’s northern hemisphere and lies between latitudes 22.5° N and 65° N, and between longitudes 270° E and 360° E. This quadrangle covers 6.5% of the planet’s surface with a total area of almost 5 million km2. Our 1:3,000,000-scale geologic map of the quadrangle was produced by photo-interpret...
Mercury’s quadrangle H02 ‘Victoria’ is located in the planet’s northern hemisphere and lies
between latitudes 22.5° N and 65° N, and between longitudes 270° E and 360° E. This
quadrangle covers 6.5% of the planet’s surface with a total area of almost 5 million km2. Our
1:3,000,000-scale geologic map of the quadrangle was produced by photo-interpret...
Unusually low reflectance material, within which depressions known as hollows appear to be actively forming by sublimation, is a major component of Mercury's surface geology. The observation that this material is exhumed from depth by large impacts has the intriguing implication that the planet's lower crust or upper mantle contains a significant v...
This work describes the newly mapped quadrangles of Mercury H02, H03, H04, H06 and the methods used for merging these products into an unique 1:3M geologic map.
The morphology and infill of several large basins on Mercury, such as Rachmaninoff and Raditladi, have been studied in detail. This work aims to provide a similar analysis of Rustaveli basin. Rustaveli is a ~200 km diameter peak-ring basin on Mercury.
New ~1:3M scale quadrangle geological maps of Mercury are being produced. Using data from NASA’s MESSENGER spacecraft, we are making a geological map of Hokusai quadrangle, for which there is no existing Mariner 10 map. Linework is drawn at 1:400k scale using ArcGIS. Craters >20km will be assigned degradation classes according to the schemes in and...
Quadrangle geological maps from Mariner 10 data cover 45% of the surface of Mercury at 1:5M scale. Orbital MESSENGER data, which cover the entire planetary surface, can now be used to produce finer scale geological maps, including regions unseen by Mariner 10.
Hokusai quadrangle (0–90° E; 22.5–66° N) is in the hemisphere unmapped by Mariner 10. It...
Rustaveli basin on Mercury (82.76° E, 52.39° N) is a 200.5 km diameter peak-ring basin. Since the approval of its name on April 24, 2012, it has not featured prominently in the literature. It is a large and important feature within the Hokusai (H5) quadrangle of which we are currently producing a 1:2M scale geological map. Here, we describe our fir...
New ~1:2M scale quadrangle geological maps of Mercury are being produced. Using orbital data from NASA’s MESSENGER satellite, we are examining Hokusai, for which there is no existing Mariner 10 map. Although work on this map has only just begun, we have made observations of important geological features which warrant further study, including Rustav...
Vents and deposits attributed to explosive volcanism occur within numerous impact craters on both the Moon and Mercury. Given the similarities between the two bodies it is probable that similar processes control this spatial association on both. However, the precise morphology and localization of the activity differs on the two bodies, indicating t...
For this issue's cover feature, Dave Rothery rounds up the haul of data and images from New Horizons' flying visit to Pluto and its large moon Charon in July.
In this work we present a new geologic map and structural analysis of the Victoria quadrangle (H2) of Mercury, along with a reconnaissance study of the geometry and kinematics of lobate scarps in this area. To this end, we produced a 1:3,000,000 geologic map of the area using the images provided by the NASA spacecraft MESSENGER , which has been orb...
At a global scale, Mercury is dominated by contractional features manifested as lobate scarps, wrinkle ridges and high-relief ridges. Here, we show that some of these features are associated with strike-slip kinematic indicators, which we identified using flyby and orbital Mercury Dual Imaging System (MDIS) data and digital terrain models. We recog...
Nili Patera is a 50 km diameter caldera at the center of the Syrtis Major Planum volcanic province. The caldera is unique among Martian volcanic terrains in hosting: (i) evidence of both effusive and explosive volcanism, (ii) hydrothermal silica, and (iii) compositional diversity from olivine-rich basalts to silica-enriched units. We have produced...
Introduction: On both Mercury and the Moon, pyroclastic deposits and endogenic vents are commonly found within impact craters (e.g., [1], [2]). It has been hypothesized that this co-location results from stalling of ascending magma in the relatively low-density brecciated zone beneath craters prior to explosive volcanic eruption [3–5]. However, the...
Introduction: Catenae are chains of more-or-less coalesced craters found on the surfaces of various planets and moons in the solar system. On the Martian moon Phobos it has been hypothe-sised that they are secondary im-pact chains, the primary craters for which are located on the sur-face of Mars [1]. On Jovian moons Callisto and Ganymede, comets f...
We analyse a seemingly-unique landform on Mercury: a conical structure, encircled by a trough, and surrounded by a 23,000 km2 relatively bright and red anomaly of a type interpreted elsewhere on the planet as a pyroclastic deposit. At first glance, this could be interpreted as a volcanically-constructed cone, but if so, it would be the only example...
The identification of widespread pyroclastic vents and deposits on Mercury has important implications for the planet's bulk volatile content and thermal evolution. However, the significance of pyroclastic volcanism for Mercury depends on the mechanisms by which the eruptions occurred. Using images acquired by the MESSENGER spacecraft, we have ident...
The duration and timing of volcanic activity on Mercury is a key indicator of the thermal evolution of the planet, and provides a valuable comparative example for other terrestrial bodies. The majority of effusive volcanism on Mercury appears to have occurred early in the planet's geological history (~4.1–3.55 Ga), but there is also evidence for ex...
Introduction: Impact craters are the dominant sur-face features of solid bodies in the Solar System and the understanding of impact process has been recently improved through advancements in numerical model-ling. In particular, the surface of Mercury shows a wide variety of impact structures corresponding to different modification processes that th...
Mercury’s compound volcanos are only hundreds of meters high. Some could have been active episodically for >1 Ga. Vents are explosively excavated and >1 km deep.
We have created a media-rich Massive Open On-line Course (MOOC) based on a theme of moons of the solar system, including on-line activities, games, and videos.
We use the buffered crater count method to investigate the sequence of events in an area with clear superposition of two volcanic units and a lobate scarp.
The first study to date pyroclastic activity on Mercury, dating the thickest deposits to 3.8-3.27 Ga and smaller-scale activity possibly within the last 1 Ga.
A geological history connecting: Caldera formation, with an ignimbrite or pluton base. Post-caldera dacite flows, resurgent dome, and mafic ring fault volcanism.
At a global scale, Mercury is dominated by contractional features manifested as lobate scarps, wrinkle ridges and high-relief ridges. Here, we show that some of these features are associ- ated with strike-slip kinematic indicators, which we identified using flyby and orbital Mercury Dual Imaging System (MDIS) data and digital terrain models. We rec...
A 27×13 km27×13 km ‘rimless depression’ 100 km inside the southwest rim of the Caloris basin is revealed by high resolution orbital imaging under a variety of illuminations to consist of at least nine overlapping volcanic vents, each individually up to 8 km in diameter. It is thus a ‘compound’ volcano, indicative of localised migration of the site...
The Syrtis Major Planum, originally mapped as unit Hs in the Greely and
Guest 1987 map [1], is a low-angle basaltic shield volcano (Figure 1).
Greeley and Guest suggested it is Hesperian (3.7 - 3.0 Ga) age,
but recent work suggests a wider range of formation ages [2]. The
edifice is a 1500 km by 1100 km (~1 % of the martian surface) basaltic
lava p...
Lobate scarps on Mercury are generally accepted to be surface
expressions of thrust faulting. This is taken as evidence of
lithospheric contraction on a global scale, reflecting either global
cooling, leading to thermal contraction and internal phase changes; or
tidal despinning, leading to collapse of an equatorial bulge; or a
combination of both....
Hollows on Mercury are sub-kilometre scale shallow, steep-sided rimless
pits. Seemingly a result of loss of material to space, they are among
several lines of evidence suggesting that the volatile budget of Mercury
is higher than previously thought. They tend to occur in clusters and
are associated with relatively high-albedo blue material ('bright...
Many >200-km basins show basin-fill lavas overthrusting the basin
edge. Low-latitude examples are dominated by E-W thrusting, implicating
late tidal despinning.
Hollows are dominantly structurally controlled, suggesting derivation of
hollow-forming volatiles from depth. Insolation influences hollowing
weakly.
Using two rheological models we calculate eruption parameters and
rheological properties for lava flows on Syrtis Major Planum.
Recent images of the surface of Mercury have revealed an unusual and intriguing landform: sub-kilometre scale, shallow, flat-floored, steep-sided rimless depressions typically surrounded by bright deposits and generally occurring in impact craters. These ‘hollows’ appear to form by the loss of a moderately-volatile substance from the planet’s surfa...
Mercury is turning out to be a planet characterized by various kinds of
endogenous hole (discounting impact craters), which are compared here.
These include volcanic vents and collapse features on horizontal scales
of tens of km, and smaller scale depressions ('hollows') associated with
bright crater-floor deposits (BCFD). The BCFD hollows are tens...
Areas of crustal convergence and shortening on Earth, Mars and Venus are
often characterized by structural domains where thrust faults are
associated with strike-slip systems [1]. In the case of Mercury most
structures maintain a wide elongated frontal scarp and only few of them
show kinematic indicators of lateral slip. The comparison between two...
Planets are common around Sun-like stars. ‘Exoplanets’ examines this type of planet. The first discovery of an exoplanet was made in 1995, and hundreds of exoplanets are now known to exist. Exoplanets have been found by detecting slight changes in a star's radial velocity, and by looking for ‘transits’ (a tiny fraction of a star's light that is cut...
‘Giant planets’ looks at Jupiter, Saturn, Uranus and Neptune, the planets that dominate the Solar System in terms of their size. How do you measure the size of a planet, and how do you study it's interior? The atmosphere of each of these planets have been observed and measured: what has been discovered during these investigations, and what is the c...
The composition and chemistry of Mercury’s regolith has been calculated from MESSENGER MASCS 0.3–1.3 μm spectra from the first flyby, using an implementation of Hapke’s radiative transfer-based photometric model for light scattering in semi-transparent porous media, and a linear spectral mixing algorithm. We combine this investigation with linear s...
Thanks to its location at low latitude and close to the terminator in the outbound view of Mercury obtained during MESSENGER’s first flyby, the Beagle Rupes lobate scarp on Mercury has been particularly clearly imaged. This enables us to interpret it as a component of a linked fault system, consisting of a frontal scarp terminated by transpressive...
Impact craters are the dominant surface features of the solid bodies of the Solar System, caused by asteroid and comet bombardment since the Solar System formation about 4.6 Gyr ago. The study of craters' statistical aspects has been applied successfully as the principal tool in dating planetary surfaces. Recently, a new planetary chronology, calle...
The Beagle Rupes lobate scarp was particularly clearly imaged during the
outbound leg of MESSENGER's first flyby, thanks to its location at low
latitude and proximity to the terminator. Previous interpretations of
mercurian lobate scarps regard them as surface expressions of thrusts
whose fault planes dip uniformly and die out at depth, and that la...
This paper discusses the data product requirements needed for X-ray
fluorescence (XRF) spectroscopy studies of planetary surfaces from a
geological perspective. For some science goals elemental ratios are
sufficient, whereas others require absolute elemental abundances with
2σ errors of <2 %.
The Mercury Imaging X-ray Spectrometer (MIXS) on the BepiColombo Mercury Planetary Orbiter (MPO) will measure fluorescent X-ray emission from the surface of Mercury in the energy range 0.5–7.5 keV, which is induced by incident solar X-rays and solar wind electrons and protons. These X-rays will reveal the elemental composition of the surface of Mer...
We describe the contributions that we expect the BepiColombo mission to
make towards increased knowledge and understanding of Mercury's surface
and composition. BepiColombo will have a larger and more capable suite
of instruments relevant for determination of the topographic, physical,
chemical and mineralogical properties of the surface than c...