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Volcanic features of the far side Aitken Crater including post-impact volcanism and volcanic events extending beyond the period of mare type crater flooding are discussed. The features attributed to extrusions of viscous lava are also discussed.
The Mars Geologic Mapping (MGM) Program was introduced by NASA in 1987 as a new initiative in the Planetary Geology and Geophysics (PGG) Program. The overall purpose of the program is to support research on topical science problems that address specific questions. Among the objectives of the project are: (1) to produce highly detailed geologic maps that will greatly increase the knowledge of the materials and processes that have contributed to the evolutionary history of Mars; (2) to define areas of special interest for possible future investigation by planned missions (Mars Observer, Mars Sample Return); and (3) to maintain the interest of the planetary community in the development of new concepts and the re-evaluation of Martian geology as new data in usable form become available. Some interesting highlights of the geologic mapping indicate that multiple flood episodes occurred at different times during the Hesperian Period in both Kasei and Maja Valles. Studies of small channels in the Memnonia, Mangala, and Tharsis regions show that fluvial events appear to have occurred during the Amazonian Period at equatorial latitudes. Flood waters occurred during the Amazonian Period at equatorial latitudes. Flood waters from Mangala Valles may have seeped into surficial materials with the subsequent development of numerous sapping channels and debris flows; this suggests that the ancient highland terrain consists of relatively unconsolidated materials. Multiple layers were observed for the first time in the ridged plains lava flows covering large areas of Lunae Planum; some wrinkle ridges in this area are associated with grabens and collapse volcanic units at Hadriaca and Tyrrhena Paterae indicates that the units may have been emplaced by gravity-driven pyroclastic flows. Unlike the north polar layered deposits, those in the south polar region show no angular unconformities or evidence of faulting and folding. Water ice in the south polar layered deposits may be protected from solar heating and sublimation by a weathering rind or lag deposit on the surface.
Two models have been proposed for the resurfacing history of Venus: (1) equilibrium resurfacing and (2) global resurfacing. The equilibrium model consists of two cases: in case 1, areas less than or equal to 0.03 percent of the planet are spatially randomly resurfaced at intervals of less than or greater than 150,000 yr to produce the observed spatially random distribution of impact craters and average surface age of about 500 m.y.; and in case 2, areas greater than or equal to 10 percent of the planet are resurfaced at intervals of greater than or equal to 50 m.y. The global resurfacing model proposes that the entire planet was resurfaced about 500 m.y. ago, destroying the preexisting crater population and followed by significantly reduced volcanism and tectonism. The present crater population has accumulated since then with only 4 percent of the observed craters having been embayed by more recent lavas. To test the equilibrium resurfacing model we have run several Monte Carlo computer simulations for the two proposed cases. It is shown that the equilibrium resurfacing model is not a valid model for an explanation of the observed crater population characteristics or Venus' resurfacing history. The global resurfacing model is the most likely explanation for the characteristics of Venus' cratering record. The amount of resurfacing since that event, some 500 m.y. ago, can be estimated by a different type of Monte Carolo simulation. To date, our initial simulation has only considered the easiest case to implement. In this case, the volcanic events are randomly distributed across the entire planet and, therefore, contrary to observation, the flooded craters are also randomly distributed across the planet.
The Deccan Traps in the Indian subcontinent represent one of the most extensive flood basalt provinces in the world. These basalts occur mainly as flat-lying, subaerially erupted tholeiitic lava flows, some of which are traceable for distances of more than 100 km. Offshore drilling and geophysical surveys indicate that a part of the Deccan subsided or was downfaulted to the west beneath the Arabian Sea. The presence of 1 to 5 m thick intertrappean sediments deposited by lakes and rivers indicates periods of quiescence between eruptions. The occurrence of numerous red bole beds among the flows suggests intense weathering of flow tops between eruptive intervals. Although the causative relationship of the Cretaceous-Tertiary (K-T) biotic extinctions to Deccan volcanism is debatable, the fact that the main Deccan eruptions straddle the K-T event appears beyond doubt from the recent Ar-40/Ar-39 ages of various Deccan flows. This temporal relationship of the K-T event with Deccan volcanism makes the petrochemical signatures of the entire Deccan sequence (basalt flows, intercalated intertrappean sediments, infratrappean Lameta beds (with dinosaur fossils), and the bole beds) pertinent to studies of the K-T event. The results of ongoing study is presented.
Field experiments were conducted to determine experimentally how well a seismometer installed using a penetrator would be coupled to the ground. A dry lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were fired at various distances to generate seismic signals. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology, although some minor differences were observed at frequencies near the upper limit of the frequency band.
Field experiments were conducted to determine how well a seismometer installed using a penetrator would be coupled to the ground. A dry-lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were at various distances to generate seismic signals. These signals were detected by the penetrator-mounted geophone assembly and by a reference geophone assembly buried or anchored to surface rock and 1-m from the penetrator. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence, and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology.
Mercury (Hg) anomalies linked to Large Igneous Provinces (LIP) volcanism have been identified in sediments across all five major mass extinctions in Earth's history. This study tests whether Hg in marine sediments is a reliable proxy linking Deccan Traps volcanic eruptions to late Maastrichtian global climate warming and the mass extinction at the Cretaceous-Paleogene boundary (KPB). Our primary test site is the Elles section in Tunisia, the auxiliary Global Stratotype Section and Point (GSSP) to El Kef. Elles has the most complete marine sedimentary record and a high average sedimentation rate of ~4.7 cm/ky. Here, we chose the Hor Hahar section in Israel to corroborate the geographic distribution of Hg fallout from Deccan volcanism. Reliability of the Hg proxy over the last 550 ky of the Maastrichtian to early Danian was evaluated based on high-resolution age control (orbital cyclostratigraphy), stable isotope climate record, Hg concentrations, biotic turnover and mass extinction. These results were correlated with the pulsed Deccan eruptive history constrained previously by U-Pb zircon geochronology. Our results support Hg as robust proxy for Deccan volcanism with large Hg spikes marking “extreme event” (EE) pulsed eruptions correlative with climate warming peaks separated by steady, less intense eruptions. Long-term global climate warming began near ~350 ky pre-KPB, reached maximum warming (3–4 °C) between 285 and 200 ky pre-KPB, followed by gradual cooling and rapid temperature drop between 45 and 25 ky pre-KPB. During the last 25 ky before the KPB, multiple Hg EE eruptions correlate with hyperthermal warming that culminated in the rapid mass extinction at Elles during ≤1000 years of the Cretaceous. These latest Cretaceous Hg peaks may correlate with massive, distal, Deccan-sourced lava flows (>1000 km long) that traversed the Indian subcontinent and flowed into the Bay of Bengal, bracketing the mass extinction. These results support Deccan volcanism as a primary driver of the end-Cretaceous mass extinction.
Results are presented of the topographic mapping of six large central volcanoes on Mars. Stereo images of the volcanoes Olympus Mons, Elysium Mons, Albor Tholus, Ceraunius Tholus, Uranius Tholus and Uranius Patera were acquired by Viking Orbiter 1, and pairs of images were compiled into topographic maps through the use of digital image measurement techniques. Olympus Mons is found to have the general form of a terrestrial basaltic shield constructed almost entirely from lava flows, however with an altitude of 20-23 km and flank slopes averaging about 4 deg; a high nominal density indicates that anomalously dense lithosphere underlies the shield. Uranius Patera is observed to be a similar feature of present relief about 2 km, with its lower flanks buried by later lava flood deposits. Elysium Mons has about 13 km of local relief with average slopes of 4.4 deg, although its upper flank slopes are significantly steeper than those of Olympus Mons, suggesting a shield volcano modified by a terminal phase of mixed volcanic activity. Albor Tholus is found to be a partially buried 3-km shield-like construct, while Ceranius and Uranius Tholus are steeper cone-like features with reliefs of about 6 and 2 km, respectively, which may be lava shield constructs modified by a terminal stage of explosive activity.
One question of great interest to those who study the evolution of the Martian atmosphere is: if there was an early, dense atmosphere that was removed, is there any mechanism that could restore it? In the case of an atmosphere removed largely by the formation of carbonates, the only obvious means of restoring it is by the thermal decomposition of the carbonates. Decomposition of carbonates under turbulently flowing lava holds great promise as a means of resupplying the atmosphere with CO2. Huppert and colleagues have modeled the emplacement of terrestrial komatiite flows and found that komatiites, even when flowing over previously emplaced and cooled komatiite flows, could melt and erode this rock to a significant depth. Based on this work, I have begun modeling the erosion of Martian carbonate deposits under turbulently flowing, komatiitic lava. Initial results from this modeling indicate that a high-volume lava flow, emerging at a temperature of, say, 1600 degrees, is capable of eroding several meters of carbonate deposits per day. If such a flow is active for a hundred days, several hundreds of meters of carbonate could be decomposed. If this process occurred over a large area, a bar or more of CO2 could be injected back into the atmosphere over an extremely short period of time. The implications of such an occurrence are intriguing. For instance, if a relatively late pulse of volcanism (such as is suggested by Frey) were to cause a large flow of lava over carbonate deposits in the northern lowlands, the resulting pulse of CO2 into the atmosphere could conceivably restore the climate to one in which liquid water could exist on the surface, or ice could flow.
Both the Moon and Mars exhibit volcanic modification of impact craters characterized by subfloor intrusions that either lift the old crater floor or result in extrusions of lava. Endogenic modification of martian craters, however, probably has involved interactions between such intrusive bodies and permafrost, as suggested by differences between lunar and martian floor-fractured craters. Such interactions raise the interesting possibility for hydrothermally concentrating ores in a manner analogous to the Sudbury structure on the Earth that may be consistent with interpretations of Viking lander results.
Thermal inertia, defined as the square root of the product of thermal conductivity, density, and specific heat, has been noted to vary in inverse proportion to porosity in Hawaiian basalts. It is presently suggested that porosities of the order of more than 80 percent are required if the low thermal inertias observed in Martian shield volcanoes are the result of pristine lava flow surface properties. An aeolian origin is held to be most likely in view of thermal measurements on Mars; the volcanic surfaces in question are anticipated to have a short lifetime in their environment.
The Mars Exploration Rover Spirit has identified five distinct rock types in the Columbia Hills of Gusev crater. Clovis Class rock is a poorly-sorted clastic rock that has undergone substantial aqueous alteration. We interpret it to be aqueously-altered ejecta deposits formed by impacts into basaltic materials. Wishstone Class rock is also a poorly-sorted clastic rock that has a distinctive chemical composition that is high in Ti and P and low in Cr. Wishstone Class rock may be pyroclastic in origin. Peace Class rock is a sedimentary material composed of ultramafic sand grains cemented by significant quantities of Mg- and Ca-sulfates. Peace Class rock may have formed when water briefly saturated the ultramafic sands, and evaporated to allow precipitation of the sulfates. Watchtower Class rocks are similar chemically to Wishstone Class rocks, and have undergone widely varying degrees of near-isochemical aqueous alteration. They may also be ejecta deposits, formed by impacts into Wishstone-rich materials and altered by small amounts of water. Backstay Class rocks are basalt/trachybasalt lavas that were emplaced in the Columbia Hills after the other rock classes were, either as impact ejecta or by localized volcanic activity. The geologic record preserved in the rocks of the Columbia Hills reveals a period very early in martian history in which volcanic materials were widespread, impact was a dominant process, and water was commonly present.
The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, thorium, and potassium. The Procellarum region has been interpreted as an ancient impact basin approximately 3200 km in diameter, though supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border the Procellarum region and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dikes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of quasi-rectangular border structures with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the elevated heat flux in the region.
The consensus regarding interpretation of Magellan radar imagery assigns Venus a young volcanic surface subjected in many areas to moderate crustal shortening. I infer that, on the contrary, ancient densely cratered terrain and large impact basins may be preserved over more than half the planet and that crustal shortening has been much overestimated. I see wind erosion and deposition as far more effective in modifying old structures. Integration with lunar chronology suggests that most of the surface of Venus may be older than 3.0 Ga and much may be older than 3.8 Ga. Broad volcanos, hug volcanic domes, plains preserving lobate flow patterns, and numerous lesser volcanic features, pocked sparsely by impact craters, are indeed obvious on Magellan imagery. Some of these postvolcanic impact craters have been slightly extended, but only a small portion has been flooded by still younger lavas. Relative ages of the young craters are indicated by the varying eolian removal of their forms and ejecta blankets and flow lobes, and the oldest are much subdued. If these young impact craters, maximum diameter 275 km, include all preserved impact structures, then their quantity and distribution indicate that Venus was largely resurfaced by volcanism approx. 0.5 Ga, subsequent eruptions having been at a much reduced rate. Away from the approx. 0.5 Ga volcanic features, much of Venus is, however, dominated by circular and subcircular features, 50-2000 km in diameter, many of them multiring, that may be mostly older impact and impact-melt structures substantially modified by wind action. Eolian erosion scoured to bedrock old ridges and uplands, including those that may be cratered terrains and the rims and outer-ring depressions of large impact basins, and removed all surficial deposits to the limits of resolution of the imagery. The complementary eolian deposits form not only dunes, wind streaks, and small plains, but also broad radar-dark plains, commonly assumed to be volcanic although lacking flow morphology, whose materials appear to be thick because they are smoothly compacted into buried craters.
The volcanic processes that formed Vallis Schr teri are not well understood. Vallis Schr teri, located on the Aristarchus Plateau, is the largest rille on the Moon, and it displays three key morphologic components: the Cobra Head, the 155-km-long primary rille, and the 240-km-long inner rille. Observations of terrestrial eruptions are applied here to help explain the morphologic relationships observed for Vallis Schr teri. The Cobra Head, a 10-km-wide source vent surrounded by a 35-kmdiameter and 900-m-high low shield, might have been constructed from fl ows, spatter, and pyroclastic deposits erupted during lava fountain events, similar to the early stages of the vent at Pu u O o in Hawaii and the fi nal morphology of Bandera crater, a cinder cone in New Mexico. The vent fed an initial sheet fl ow controlled by preeruption topography. A channel formed within this sheet fl ow was the foundation for the primary rille, which deepened through construction and thermomechanical erosion by lava. The inner rille is confi ned to the fl at fl oor of the primary rille and is characterized by tight gooseneck meanders. This rille crosscuts the distal scarp of the primary rille and extends toward Oceanus Procellarum. This enigmatic relationship can be explained through backup, overfl ow, and diversion of the lava into a new rille that eroded into the margin of the primary rille. Similar backup, overfl ow, and redirection of the lava fl ow were observed during the 1984 Mauna Loa eruption in Hawaii. Analysis of the fi nal morphology of lunar rilles provides key information about lunar volcanic processes and insight into the local stratigraphy.
Volcanoes are an integral part of the Earth system and are formed by intrusions of magma that 'bubble up’ from Earth’s interior (e.g., lava lamp). They can form above thin areas of the Earth’s crust/ lithosphere known as ‘hot spots or mantle plumes’ such as the Hawaiian Islands or Yellowstone National Park. More commonly they form along ‘subduction zones’ where the thinner oceanic tectonic plates slide below the thicker continental plates. Many of the most active (and violent) volcanos lie along subduction zones known as the Pacific 'Ring of Fire’.
Ex-situ carbon mineralization is a process by which CO2 is reacted with alkaline silicate minerals and rocks to produce stable carbonate materials, which can be used for other industrial processes. Arizona, U.S.A., hosts abundant surficial mafic rocks in three young volcanic fields, Geronimo-San Bernardino, San Francisco, and Springerville, and other distributed locations throughout the state. We created a Mafic Rock Resource Inventory (MRRI) that categorizes geochemical, physical, and textural characteristics of a diverse suite of surficial mafic rock samples and provide a benchmark reaction dataset parameterizing the temperature, pressure, and pH conditions best suited ex-situ mineralization in different rock types. MRRI data is publicly available online via a map-viewer. We establish two reaction condition sets, varied in temperature, pressure, and pH, where crystal-rich and glassy rocks reach maximum reaction extent and different carbonate phases are formed. Systematic ex-situ mineralization experiments on 21 diverse rock types show trends in geochemical, mineralogical, and reactivity behavior and establish maximum effective capture capacity. From this, scoria cones in three Arizona volcanic fields have a ~62 Gt effective CO₂ storage capacity with one of the fields having a ~42 Gt storage capacity in lava flows. Reactivity results have applications to alkaline mafic rock resources exposed globally, including producing additional effective storage capacity estimates and scaled commercialization of mafic rock ex-situ mineralization, should reaction extents be improved through advances in mineralization techniques. MRRI data were used to create a Direct Air Capture to Mineralization (DACM) systems model, technoeconomic analysis, and life-cycle assessment. These documents are presented as three appendices.
Morphological measurements on six well-defined volcanic flows near the summit of the Martian volcano Ascraeus Mons were used to calculate the yield strength and viscosity of the lavas. The results are similar to values obtained for flows on other Martian and terrestrial shield volcanoes. Calculated viscosities are generally higher than measured viscosities for basaltic lavas but considerably smaller than rhyolite or dacite viscosities. The estimated rheologic properties of the Martian flows are most consistent with basaltic or basaltic andesite lavas, but some individual flows could consist of more evolved lavas.