Investigations of Morphologies and Emplacement Mechanisms of Volcanically-Derived Landforms on the Moon and Mars

abstract: Previous workers hypothesized that lunar Localized Pyroclastic Deposits (LPDs) represent products of vulcanian-style eruptions, since some have low proportions of juvenile material. The objective of the first study is to determine how juvenile composition, calculated using deposit and vent volumes, varies among LPDs. I used Lunar Reconnaissance Orbiter Camera Narrow Angle Camera (LROC NAC) digital terrain models (DTMs) to generate models of pre-eruption surfaces for 23 LPDs and subtracted them from the NAC DTMs to calculate deposit and vent volumes. Results show that LPDs have a wide range of juvenile compositions and thinning profiles, and that there is a positive relationship between juvenile material proportion and deposit size. These findings indicate there is greater diversity among LPDs than previously understood, and that a simple vulcanian eruption model may only apply to the smallest deposits. There is consensus that martian outflow channels were formed by catastrophic flooding events, yet many of these channels exhibit lava flow features issuing from the same source as the eroded channels, leading some authors to suggest that lava may have served as their sole agent of erosion. This debate is addressed in two studies that use Context Camera images for photogeologic analysis, geomorphic mapping, and cratering statistics: (1) A study of Mangala Valles showing that it underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian, consistent with alternating episodes of flooding and volcanism. (2) A study of Maja Valles finds that it is thinly draped in lava flows sourced from Lunae Planum to the west, rendering it analogous to the lava-coated Elysium outflow systems. However, the source of eroded channels in Maja Valles is not the source of the its lava flows, which instead issue from south Lunae Planum. The failure of these lava flows to generate any major channels along their path suggests that the channels of Maja Valles are not lava-eroded. Finally, I describe a method of locating sharp edges in out-of-focus images for application to automated trajectory control systems that use images from fixed-focus cameras to determine proximity to a target.Dissertation/ThesisDoctoral Dissertation Geological Sciences 201

Progress and prospects for research on Martian topographic features and typical landform identification

The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science

Planet Mercury: volatile release on a contracting world

This thesis investigates the geological processes by which materials containing high concentrations of volatile substances have been delivered to the surface of the planet Mercury throughout its history, despite global contraction, which could be expected to impede the replenishment of these materials from depth. With the aid of high-resolution data from the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft, I perform detailed analyses of the two types of geological features most indicative of the action of volatiles at Mercury’s surface: flat-floored depressions known as ‘hollows’, and pits and deposits thought to be the products of explosive volcanism. For hollows, I seek to clarify the nature of the substance lost to form them and the mechanisms by which this has been introduced to, and lost from, the surface recently enough to explain their pristine appearance. I produce a global catalogue of hollows, study their local associations, and investigate their spectral character, finding evidence that they form primarily by sublimation of a moderately volatile substance, potentially a sulfide, from a specific low-reflectance substrate exhumed and exposed by meteorite impacts. To better understand explosive volcanism, I investigate its longevity and the processes promoting it at specific locations. Through identifying, dating and characterising proposed pyroclastic deposits and vents, I show that putative explosive volcanism was more long-lived than voluminous effusive eruptions, that its occurrence is tectonically controlled, and that its eruptive style indicates magma storage prior to eruption, at greater depths than on the more tectonically-neutral Moon. This indicates that, rather than precluding it, global contraction favoured volcanic explosivity by promoting magma storage during which volatiles could become concentrated in the magma. Furthermore, because processes concentrating volatiles have been important in the genesis of both hollows and explosive volcanism, their occurrence does not necessarily indicate a high planetary bulk volatile fraction

The Formation and Degradation of Planetary Surfaces: Impact Features and Explosive Volcanic Landforms on the Moon and Mars

abstract: Impact cratering and volcanism are two fundamental processes that alter the surfaces of the terrestrial planets. Though well studied through laboratory experiments and terrestrial analogs, many questions remain regarding how these processes operate across the Solar System. Little is known about the formation of large impact basins (>300 km in diameter) and the degree to which they modify planetary surfaces. On the Moon, large impact basins dominate the terrain and are relatively well preserved. Because the lunar geologic timescale is largely derived from basin stratigraphic relations, it is crucial that we are able to identify and characterize materials emplaced as a result of the formation of the basins, such as light plains. Using high-resolution images under consistent illumination conditions and topography from the Lunar Reconnaissance Orbiter Camera (LROC), a new global map of light plains is presented at an unprecedented scale, revealing critical details of lunar stratigraphy and providing insight into the erosive power of large impacts. This work demonstrates that large basins significantly alter the lunar surface out to at least 4 radii from the rim, two times farther than previously thought. Further, the effect of pre-existing topography on the degradation of impact craters is unclear, despite their use in the age dating of surfaces. Crater measurements made over large regions of consistent coverage using LROC images and slopes derived from LROC topography show that pre-existing topography affects crater abundances and absolute model ages for craters up to at least 4 km in diameter. On Mars, small volcanic edifices can provide valuable insight into the evolution of the crust and interior, but a lack of superposed craters and heavy mantling by dust make them difficult to age date. On Earth, morphometry can be used to determine the ages of cinder cone volcanoes in the absence of dated samples. Comparisons of high-resolution topography from the Context Imager (CTX) and a two-dimensional nonlinear diffusion model show that the forms observed on Mars could have been created through Earth-like processes, and with future work, it may be possible to derive an age estimate for these features in the absence of superposed craters or samples.Dissertation/ThesisDoctoral Dissertation Geological Sciences 201

Characterisation of Isidis Planitia and the Beagle 2 Landing Site on Mars

Isidis Planitia is a large impact basin on Mars. I have determined that the extensive numbers of sub-kilometre sized cones and cone chains in the basin are the result of deposition of sediments by retreating ice in a process analogous to terrestrial terminal moraine formation, along with the formation of pingos, mud- and cryovolcanoes by the expansion of freezing fronts into a subsurface containing liquid water. I have interpreted the sinuous ridges within the basin as analogous to terrestrial eskers. Much of the research I have carried out uses Mars Orbiter Laser Altimeter (MOLA) data to study the topography of the basin. I have interpolated and detrended the data in order to detect subtle variations in topography that are obscured by the the basin slope. I have analysed the large scale ridges within the basin, determining that they are the result of compressional tectonics forming normal faults, analogous to lunar wrinkle ridges. I have demonstrated that a model involving tectonic loading of the basin convincingly explains the division of ridges into an inner zone of concentric thrusting faults, and an outer zone of radially thrusting faults, and also provides an explanation for the gravitational anomaly found within the basin. I have analysed the larger impact craters in the basin, and determined that they show evidence of interaction with buried volatiles at the time of their formation. I have also identified a number of previously unknown buried craters within the basin, and calculated the age of the buried unit in which they formed to be Lower-to-mid-Hesperian. I have investigated thermal and other surface properties of the basin surface. Finally, I have drawn the available evidence together to determine a history of events that have shaped the surface and subsurface of the basin during the Hesperian and Amazonian Epochs

Supervolcanoes Within an Ancient Volcanic Province in Arabia Terra, Mars

Several irregularly shaped craters located within Arabia Terra, Mars represent a new type of highland volcanic construct and together constitute a previously unrecognized martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae display a range of geomorphic features related to structural collapse, effusive volcanism, and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulfur and erupted fine-grained pyroclastics from these calderas likely fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. Discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars

North Gale Landform and the Volcanic Sources of Sediment in Gale Crater Mars

An investigation into the origins of a previously unidentified landform north of Gale Crater, Mars (North Gale Landform, NGL) using remotely sensed datasets and morphological mapping has determined that it is a volcanic construct that collapsed and produced a hummocky terrain deposit to the south. Volcaniclastic sediments have been detected in the sedimentary rocks of Gale Crater by APXS. They can be grouped into distinct classes: Jake_M and Bathurst_Inlet. Jake_M are float rocks and cobbles made of igneous sediments with evolved, alkaline compositions and pitted, dusty surfaces. Bathurst_Inlet are least altered potassic basaltic sediments in siltstone sandstone to matrix-supported conglomerates. Simple petrologic models demonstrate there is a need for more than one distinct crystalline source. Bathurst_Inlet class targets are not mantle melts and Jake_M class targets are not differentiated from Bathurst_Inlet or Adirondack. NGL may be one source for the volcaniclastic sediments in Gale Crater

Geomorfología glaciar del flanco noroeste del volcán Hectes Tholus, Marte

Tesis Doctoral de la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, Departamento de Geodinámica, leída el 05-11-2015El volcán Hecates Tholus (32.18°N, 150.28ºE; cuadrante MC-7), de unos 180 km de diámetro y 5.300 metros de altura, es el único edificio de la provincia volcánica de Elysium, en las Tierras Bajas de Marte, en el que se han descrito rasgos geomorfológicos que podrían estar causados por procesos glaciares. Además, distintos autores relacionan la red radial de canales que surcan las laderas del volcán como causadas por la fusión de un antiguo casquete glaciar en la cima del edificio, siendo éste un ejemplo más de las intensas interacciones magma-agua en esta región del planeta, cercana al antiguo océano marciano y que dieron lugar a fenómenos muy interesantes, como los terrenos caóticos de Galaxias Chaos, a pocos kilómetros del volcán. Una característica muy particular de este edificio volcánico es la presencia de dos depresiones anidadas en la base de la ladera Noroeste, de 20 y 60 km de diámetro. La menor de ellas (Depresión A), situada a mayor altitud, ha sido interpretada por algunos autores como causada por una erupción lateral del volcán hace unos 350 Ma. Sin embargo, la de mayor diámetro y situada a menor altitud (Depresión B), no tiene un origen claro, aunque se han discutido distintas hipótesis. En cualquier caso, es especialmente en el interior de estas depresiones donde se han encontrado los rasgos geomorfológicos que podrían estar causados por actividad glacial, como posibles cordones morrénicos y depósitos de till...Hecates Tholus volcano (32.18°N, 150.28ºE; MC-7 quadrangle) is the only edifice of the Elysium volcanic province, at the lowlands of Mars, showing evidence of glacial activity, as deduced from the geomorphological study. This work completes the previous regional works with the aim of refine our knowledge about the glacial events occurred at this site of Mars. We build a detailed geomorphological mapping (1:100.000 in scale) of the lower NW flank of the edifice (31.8º-33.08ºN, 148.37º-149.38ºE), where the glacial ”marsforms” concentrate, based on the use of CTX images. Moreover, we performed detailed crater size-frequency distribution, geomorphological, morphometric, compositional, and thermal analysis to finish the cartography and get the necessary evidences to model the glacial evolution of the area. Those analyses were possible thanks to the use of a wide variety of images, including HRSC, HiRISE, MOC, and THEMIS, as well as HRSC-derived topographic data, THEMIS-derived Brightness surface temperature, TES-derived thermal inertia maps, and SHARAD ground penetration radargrams, everything integrated into a Geographic Information System...Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEunpu

Wet-Based Glaciation on Mars

Mars is a glacial planet. It hosts water ice in large polar ice caps, and in thousands of ‘viscous flow features’ in its mid latitudes that are thought to be debris-covered water ice glaciers. These ice deposits range between a few million to ~1 billion years in age and formed during Mars’ most recent epoch, the late Amazonian. The late Amazonian was characterised by extremely cold and arid climate conditions that are not conducive to melting of ice. Consequently, late-Amazonian glaciation has been dominated by cold-based glacier thermal regimes. However, the recent discovery of an esker (a ridge of sediment deposited by meltwater flowing through a tunnel within or beneath glacial ice) associated with a viscous flow feature in the Phlegra Montes region of Mars’ northern mid latitudes provided the first indicative evidence that wet-based glaciation occurred in at least one location during the late Amazonian. In this thesis, I present the discovery of a second candidate esker associated with a viscous flow feature, in the NW Tempe Terra region of Mars’ northern mid latitudes. I argue that the remarkably similar geologic settings of the NW Tempe Terra and Phlegra Montes candidate eskers (both within tectonic rift/graben valleys) suggests that geothermal heating, possibly with an additional component of viscous strain heating within the basal ice, was a prerequisite for basal melting under cold climate conditions. I then characterise the 2D and 3D morphometries of these candidate eskers, undertake comparisons with the morphometries of ancient putative eskers on Mars and eskers on Earth, and develop conceptual models for the dynamics of esker formation in NW Tempe Terra. Finally, I present a geomorphic map of Chukhung crater, Mars, which hosts esker-like sinuous ridges associated with viscous flow features and provides a case study of the ongoing challenges for esker identification on Mars

The Volcanic Evolution of Syrtis Major Planum, Mars

This thesis explores the geological history of the Syrtis Major Planum volcanic province on Mars. The primary aims are (i) to differentiate the various units that make up the lava plain of Syrtis Major Planum, (ii) to investigate the formation of the central caldera complex, and (iii) to understand how the volcanic architecture has evolved over time in the regional contex. The methodology applied is that of planetary geological mapping using remote sensing data. Two new morpho-stratigraphic maps of Syrtis Major Planum have been produced. Map 1, a 1:2,000,000 scale map, uses 100 m/pixel THEMIS data as the base layer, and draws on 6 m/pixel CTX data to provide additional information. Map 2 is a 1:250,000 scale map of the Nili Patera caldera and uses base layer mosaics of CTX data and CTX Digital Terrain Models. The mapping shows that there were two major phases of magmatism at Syrtis Major. The first phase (~3.6 Ga – ~3.2 Ga) consisted of tube-fed lava plains interleaved with giant (>300 km) tabular lava flows emplaced from the centre of the planum. By the end of this phase, a fractionally crystallised magma reservoir, partially melting the hydrated sediments of the underlying Noachian highlands, had developed. The eruptive products of this magma reservoir include an ignimbrite, now exposed in Nili Patera. The second phase of magmatism (~2.7 Ga - ~2.2 Ga) consisted of temporally sporadic volcanism, spatially concentrated in the central caldera complex, and includes two examples of high-silica lava units. These derived from partial melting of the fractionally crystallised magma reservoir in the presence of hydrothermal fluids. The evolution of lava emplacement style and composition over time is best explained by the interaction between the waxing to waning stages of a mantle plume with the underlying Noachian terrain. This interaction led to the distinctive morphology of the volcanic shield, the explosive formation of the calderas, and the unusual compositions found within the central caldera complex. The volcanism of Syrtis Major is therefore defined both by the epoch in which it occurred, and the composition of the crust in which it formed