Proceedings of the MEVTV Workshop on The Evolution of Magma Bodies on Mars

The workshop focused on many of the diverse approaches related to the evolution of magma bodies on Mars that have been pursued during the course of the Mars Evolution of Volcanism, Tectonism, and Volatiles (MEVTV) Program. Approximately 35 scientists from the Mars volcanology, petrology, geochemistry, and modeling communities attended. Segments of the meeting concentrated of laboratory analyses and investigations of SNC meteorites, the interpretation of Viking Orbiter and Lander datasets, and the interpretation of computer codes that model volcanic and tectonic processes on Mars. Abstracts of these reports are presented

Depth/diameter relationships of fresh craters within Hesperia Planum, Mars

Meteorite impact craters represent important geological features for revealing the near-surface layers of a planetary surface. In the case of Mars, this characteristic was proposed as a useful method to study spatial variations of such attributes as the distribution of sub-surface volatiles, and heat flow. Using the Planetary Image Cartography System (PICS) software, a quantitative analysis was completed of the geometry of fresh impact craters in the Hesperia Planum region of Mars, where an uniform target material and optimum viewing geometry make possible an analysis of target effects over a large geographic region. Because of the morphologic similarity to the lunar maria, it is likely that Hesperia Planum comprises a series of flood lavas that partially infilled topographic depressions within the Martian highlands. Measurements of partially buried crater rims suggest that the lava flows within Hesperia Planum are between 200-400 m thick

Significant achievements in the planetary geology program, 1981

Recent developments in planetology research are summarized. Important developments are summarized in topics ranging from solar system evolution, comparative planetology, and geologic processes, to techniques and instrument development for future exploration

The Interaction of Impact Melt, Impact-Derived Sediment, and Volatiles at Crater Tooting, Mars

We are producing a 1:200K geologic map of Tooting crater, Mars. This work has shown that an incredible amount of information can be gleaned from mapping at even larger scales (1:10K 1:25K) using CTX and HiRISE data. We have produced two new science papers (Morris et al., 2010; Mouginis-Mark and Boyce, 2010) from this mapping, and additional science questions continue to arise from our on-going analysis of Tooting crater: 1) What was the interplay of impact melt and volatile-rich sediments that, presumably, were created during the impact? Kieffer and Simonds [1980] predicted that melt would have been destroyed during impacts on Mars because of the volatiles present within the target we seek to understand if this is indeed the case at Tooting crater. We have identified pitted and fractured terrain that formed during crater modification, but the timing of the formation of these materials in different parts of the crater remains to be resolved. Stratigraphic relationships between these units and the central peak may reveal deformation features as well as overlapping relationships. 2) Morris et al. [2010] identified several lobate flows on the inner and outer walls of Tooting crater. It is not yet clear what the physical characteristics of the source areas of these flows really are; e.g., what are the sizes of the source areas, what elevations are they located at relative to the floor of the crater, are they interconnected, and are they on horizontal or tilted surfaces? 3) What were the details of dewatering of the inner wall of Tooting crater (Fig. 1)? We find evidence within Tooting crater of channels carved by water release, and the remobilization of sediment (which is inferred to have formed during the impact event). Sapping can be identified along the crest of unit 8 near the floor of the crater (Fig. 2a, 2b). This unit displays amphitheater-headed canyons that elsewhere on Mars are typically attributed to water leaking from the substrate [Laity and Malin, 1985; Malin and Edgett, 2000]

The geological history of Nili Patera, Mars

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 a new geological map using three mosaicked 18 m/pixel Context Camera digital elevation models, supplemented by Compact Remote Imaging Spectrometer for Mars Hyperspectral data. The map contextualizes these discoveries, formulating a stratigraphy in which Nili Patera formed by trapdoor collapse into a volcanotectonic depression. The distinctive bright floor of Nili Patera formed either as part of a felsic pluton, exposed during caldera formation, or as remnants of welded ignimbrite(s) associated with caldera formation—both scenarios deriving from melting in the Noachian highland basement. After caldera collapse, there were five magmatic episodes: (1) a basaltic unit in the caldera's north, (2) a silica-enriched unit and the associated Nili Tholus cone, (3) an intrusive event, forming a ~300 m high elliptical dome; (4) an extrusive basaltic unit, emplaced from small cones in the east; and (5) an extreme olivine-bearing unit, formed on the western caldera ring fault. The mapping, together with evidence for hydrated materials, implies magmatic interaction with subsurface volatiles. This, in an area of elevated geothermal gradient, presents a possible habitable environment (sampled by the hydrothermal deposits). Additionally, similarities to other highland volcanoes imply similar mechanisms and thus astrobiological potential within those edifices

Crater geometry and ejecta thickness of the Martian impact crater Tooting

We use Mars Orbiter Laser Altimeter (MOLA) topographic data and Thermal Emission Imaging System (THEMIS) visible (VIS) images to study the cavity and the ejecta blanket of a very fresh Martian impact crater ~29 km in diameter, with the provisional International Astronomical Union (IAU) name Tooting crater. This crater is very young, as demonstrated by the large depth/ diameter ratio (0.065), impact melt preserved on the walls and floor, an extensive secondary crater field, and only 13 superposed impact craters (all 54 to 234 meters in diameter) on the ~8120 km^2 ejecta blanket. Because the pre-impact terrain was essentially flat, we can measure the volume of the crater cavity and ejecta deposits. Tooting crater has a rim height that has 500 m variation around the rim crest and a very large central peak (1052 m high and >9 km wide). Crater cavity volume (i.e., volume below the pre-impact terrain) is ~380 km^3 and the volume of materials above the pre-impact terrain is ~425 km^3. The ejecta thickness is often very thin (<20 m) throughout much of the ejecta blanket. There is a pronounced asymmetry in the ejecta blanket, suggestive of an oblique impact, which has resulted in up to ~100 m of additional ejecta thickness being deposited down-range compared to the up-range value at the same radial distance from the rim crest. Distal ramparts are 60 to 125 m high, comparable to the heights of ramparts measured at other multi-layered ejecta craters. Tooting crater serves as a fresh end-member for the large impact craters on Mars formed in volcanic materials, and as such may be useful for comparison to fresh craters in other target materials.The Meteoritics & Planetary Science archives are made available by the Meteoritical Society and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Application of Interferometric Radars to Planetary Geologic Studies

Radar interferometry is rapidly becoming one of the major applications of radar systems in Earth orbit. So far the 2000 flight of the Shuttle Radar Topographic Mission (SRTM) is the only dedicated U.S. radar to be flown for the collection of interferometric data, but enough has been learned from this mission and from the use of foreign partner radars (ERS-1/2, Radarsat, ENIVISAT and JERS-1) for the potential planetary applications of this technique to be identified. A recent workshop was organized by the Jet Propulsion Laboratory and the Southern California Earthquake Center (SCEC), and was held at Oxnard, CA, from October 20th - 22nd, 2004. At this meeting, the major interest was in terrestrial radar systems, but approx. 20 or the approx. 250 attendees also discussed potential applications of interferometric radar for the terrestrial planets. The primary foci were for the detection of planetary water, the search for active tectonism and volcanism and the improved topographic mapping. This abstract provides a summary of these planetary discussions at the Oxnard meeting

Polygenic eruptions on Alba Patera, Mars

A combination of photogeologic mapping, analysis of Viking Orbiter thermal inertia data, and numerical modelling of eruption conditions has permitted us to construct a new model for the evolution of the martian volcano Alba Patera. Numerous digitate channel networks on the flanks of the volcano are interpreted to be carved by sapping due to the release of non-juvenile water from unconsolidated flank deposits. Using the thermal inertia measurements, we estimate the particle size of these deposits to be 3-10 μm, which, together with theoretical modelling of the disperison of explosively derived volcanic materials, leads us to conclude that the flank deposits on Alba Patera are low-relief pyroclastic flows. The recognition of numerous late-stage summit and sub-terminal lava flows thus makes Alba Patera a unique martian volcano that is transitional between the older pyroclastic-dominated highland paterae and the more recent effusive central-vent volcanoes such as the Tharsis Montes