The surface expression of intrusive volcanic activity on Mars

Post contributed by Peter Fawdon, Dept. of Earth and Planetary Sciences, Birkbeck, University of London, UK.

Volcanism is an important process that can be observed on the surface of many planetary bodies. Not all magma bodies erupt extrusively onto the planet’s surface, many simply stall within the crust, cooling slowly over millions of years to form igneous intrusions. On Earth erosion and uplift expose the frozen core of ancient volcanoes relatively frequently, however, it is considerably more difficult to investigate this intrusive magmatism on other planets.

Figure1

Figure 1 shows a perspective view across Nili Patera. This view is generated in ArcScene using data from a mosaic of three CTX elevation models and orthoimages. The view shows Nili Tholus and the associated bright central lava unit as well as the graben along the top of the uplifted region of the western caldera floor.

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Martian Maars: valuable sites in the search for traces of past martian life

Post contributed by Dr. Sandro Rossato, Department of Geosciences, University of Padova, Padova, Italy

Fig1

Figure 1: Terrestrial maars. (a) is a group of three maars filled with water in the Eifel region, Germany (rim-to-rim diameter ~0.5-1 km) (“Maare” by Martin Schildgen – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Maare.jpg#/media/File:Maare.jpg). (b) shows the Wabah maar, located in Saudi Arabia (rim-to-rim diameter ~2 km) (courtesy of Vic Camp, San Diego State University).

Terrestrial maar-diatremes are small volcanoes (see this previous post for a general description) which have craters whose floor lies below the pre-eruptive surface and are surrounded by a tuff ejecta ring 2-5 km wide (Figure 1) that depends on the size of the maar itself and on the depth of the explosion (Lorenz, 2003). Maar-diatremes constitute highly valuable sites for in situ investigations on planetary bodies, because they expose rocks at the surface from a great range of crustal depths and are sites which could preferentially preserve biomarkers.

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Young volcanism on Mercury

Post by Carolyn Ernst, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA.

Prior to 2008, less than half of Mercury’s surface had been imaged at close range, during the flybys of Mariner 10 in the mid-1970s. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft completed three flybys of the planet in 2008 and 2009 on its way to insertion into orbit about Mercury on 18 March 2010 and viewed most of the planet’s surface that had never before been seen by a spacecraft. These MESSENGER images have helped to confirm some Mariner-10-based hypotheses and have elicited new science questions to be investigated.

September

Image 1: Narrow-angle camera mosaic of Rachmaninoff basin, 290 km in diameter, as seen during MESSENGER’s third Mercury flyby on 29 September 2009. Orthographic projection, ~ 440 m/pixel, centered at ~28ºN, 58ºE. MESSENGER images 0162744128 and 0162744150, credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

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Mercury’s Mighty Valles

Post by Dr. Paul K. Byrne, Carnegie Institution of Washington, USA

 Channel-like landforms termed “valles” (sing. “vallis”) have been observed on the Moon, Mars, and Venus, and recent results from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission show that the innermost planet hosts its own brand of valles, too. Resembling the broad outflow channels on Mars and Venus, five shallow, linear depressions form a channelized network at high latitudes in Mercury’s northern hemisphere. These valles are situated adjacent to expansive northern volcanic plains that cover some 6% of the planet’s surface, and likely conducted voluminous, low-viscosity lavas from these plains southward.

Image 1: This vallis has the steep sides, smooth floors, and erosional residuals characteristic of Mercury’s broad valles, and likely channeled lavas from left to right across the image. The image has a field of view of ca. 150 km. The 57°N parallel and 115°E meridian are shown, and Kofi basin is labeled. The image is a portion of MESSENGER’s Mercury Dual Imaging System (MDIS) global monochrome basemap, which has a resolution of 250 meters per pixel.

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Lava temperatures determine flow composition on Earth and Io.

Post by Robert Wright, and Mary C. Bourke,

Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, US.

Department of Geography, Trinity College, Dublin, Ireland.

Image 1: A Giant plume from Io’s Tvashtar volcano composed of a sequence of five images taken by NASA’s New Horizons probe on March 1st 2007, over the course of eight minutes from 23:50 UT. The plume is 330 km high, though only its uppermost half is visible in this image, as its source lies over the moon’s limb on its far side. Image source from NASA.

The temperature at which active lava is erupted correlates well with the composition of the lava.  Mafic lavas may be up to 200-330 degrees celsius hotter than felsic lavas. The range of temperatures observed on active lava surfaces can also be used to determine the style with which the lava is erupted (i.e. as aa or pahoehoe lava flows, as lava lakes, or as lava domes). This is possible because the ease with which the crust is fractured depends on the volumetric flux of lava and its rheology (Image 2). As a result, lava bodies that fracture their cool crusts more easily (like aa flows) have hotter temperature distributions than those that fracture their upper surfaces less readily (such as viscous lava domes). (more…)

Inflated Lava Flows on Earth and Mars

Post by Dr. W. Brent Garry1, Dr. Jacob E. Bleacher2, Dr. James R. Zimbelman3, and Dr. Larry S. Crumpler4

  1. Planetary Science Institute, Tucson, AZ, 85719, USA
  2. Planetary Geodynamics Laboratory, Code 698, NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
  3. Center for Earth and Planetary Studies, Smithsonian Institution, National Air and Space Museum, Washington, DC, 20013, USA
  4. New Mexico Museum of Natural History and Science, Albuquerque, NM, 87104, USA

In volcanology, we are traditionally taught about basaltic lava flows advancing as toes of pāhoehoe or as channeled ‘a‘ā flows.  However, under the right emplacement conditions, some basaltic sheet flows will inflate (thicken) from only a few centimeters or meters to almost 20 meters in height.  This process occurs when lateral advancement of the flow is inhibited and liquid lava is injected underneath the solid crust of stalled sections of the flow field, causing the crust to uplift over an expanding liquid core.  The study of inflated lava flows on Earth reveals distinctive morphologic features related to this process including tumuli, inflated sheet lobes (Image 1), squeeze ups, and inflation-rise pits [1,2].  The McCartys lava flow (Image 2) is a 48-km-long, basaltic lava flow in El Malpais National Monument, near Grants, New Mexico that exhibits many of the complex morphologic features related to the process of lava flow inflation.  By studying the morphologic features that are characteristic of inflated lava flows on Earth, we can begin to identify this style of lava flow on other planetary bodies, including the Moon and Mars [3,4,5].

Image 1

Image 1. Geologist Dr. Jake Bleacher stands on the edge of a 12 meter high inflated sheet lobe in the McCartys lava flow, New Mexico. This inflated lobe continues in the foreground and extends in the distance along the left side of the photograph. Cracks, up to 8 meters deep, have formed along the margin of the lobe as the brittle crust had to accommodate for the inflation. The lower elevation unit seen in the central part of this photograph is formed from breakouts along the margin of this inflated sheet lobe and has a hummocky and swale surface texture. Photograph by W. Brent Garry. Full Size Image.

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Lunar Sinuous Rille

Post by Scott MestPlanetary Science Institute, Tucson, AZ 85719, USA.

Lunar sinuous rilles (German for ‘groove’) consist of long, narrow depressions in the lunar surface that meander in a curved path across the surface and morphologically resemble terrestrial fluvial channels (Image 1). Sinuous rilles are generally up to several kilometers wide and hundreds of kilometers in length. On the Moon, sinuous rilles are found within volcanic terrains such as the extensive lunar mare. Their morphology and association with volcanic deposits suggests that they are the remains of lava channels or collapsed lava tubes.

Image 1

Image 1: Part of LROC image M115429448L (resolution is 0.970 m/pixel) showing a close-up of a sinuous rille (arrows) that cuts through dark plains (p) and adjacent hilly (h) materials on the floor of Schrödinger.

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Pseudocraters on Earth and Mars

Post by Dr. Jim Zimbelman , Center for Earth and Planetary Studies, Smithsonian Institution, Washington DC, USA.  

November_10

Image 1. View of pseudocrater at Lake Myvatn, Iceland (JRZ, 8/25/10).

Pseudocraters are distinctive landforms generated when a lava flow moves across ground containing either water or ice; the heat from the lava causes the water or ice to flash to steam, generating localized explosions through the lava.  In the Eifel area of Germany, such explosion craters are often (but not always) later filled with water, and they are called maars.  Important aspects of their formation, which distinguishes them from cinder cones and other monogenetic volcanic vents, is the lack of a source for erupting lava beneath the lava flow or resulting crater; the explosive action is strictly the result of the sudden generation of steam resulting from the heat of the overlying lava flow.  Pseudocraters are typically much broader and shallower than cinder cones, and they may excavate through the entire thickness of the overlying lava flow, ejecting some materials from the rock beneath the flow.  A classic locality for pseudocraters is the Lake Myvatn area of northern Iceland, where a 2000-year-old lava flow moved across wet or icy ground, generating numerous rootless explosion craters that were subsequently surrounded by the shallow waters of Lake Myvatn (Images 1 and 2). (more…)

Low-Latitude Landscape of Fire and Ice on Mars

Post by Mark Bishop.

Cone fields of the Tartarus Colles of Mars (~190° W, 26° N) comprise part of the volcanic province of the Elysium Rise. They lie amongst the mesas, ridges, small knobs and hills from which the region derives its name. Considerable interest exists in regard to cone location and origin, as their occurrence may be associated with recent volcanism, as well as the occurrence of near surface ground ice; the presence of which has consequences for past and present climate, astrobiological activity, and future exploration.

Cone fields, Mars

Image 1: MOC NA image M08-01962 (4.52 m/pixel) showing the cone fields and enlarged insets of geomorphic features. Geomorphic details are highlighted and numbered (1-3). Illumination is from the left.

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Caves on Mars

Post by Dr. Bradley J. Thompson.

On Earth, caves are naturally formed subterranean chambers that form unique geologic and biologic environments. Although terrestrial caves are commonly formed in limestone where slightly acidic water has partially dissolved the host rock, caves can also form in ice or even in solidified lava (flowing lava will often form a roofed-over channel or tube that remains hollow once the lava cools and solidifies). Caves provided early humans with their first form of shelter, and the walls of some caves still record evidence of their presence in the form of cave paintings. From an environmental standpoint, caves provide near constant temperature and relative humidity year-round, and thus can serve as a refuge when conditions at the surface are too extreme.

Collapse pit, Arsia Mons, Mars

Subset of HIRISE image PSP_004847_1745 showing the illuminated wall of a collapse pit on the north east flank of a giant volcano on Mars, Arsia Mons.

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Lava Flows on Mars, Io, and Earth

Post by Dr. Jim Zimbelman

Lava flows are one of the common landforms encountered on various objects throughout the inner solar system, as well as on Jupiter’s volcanically active moon Io. Cameras and other remote sensing instruments on various spacecraft have returned an incredible amount of data about lava flows on planetary surfaces. Here we will highlight a couple of examples, along with recent work on lava flows on Earth that is providing new insight into how we can study lava flows on other planets.

Lava Flow on Ascraeus Mons, Mars

Image 1: The image is a portion of frame S08-02516 taken by the Mars Orbiter Camera, which shows part of a heavily cratered lava flow on the flank of the Ascraeus Mons shield volcano in the Tharsis region. The abundance of impact craters on the flow indicates that it is not very recent.

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Valley Networks on Venus

Posted by Dr. Goro Komatsu, IRSPS, Univ. G.d’Annunzio, Italy.  

(Re-posted from IAG Image of the Month, December, 2007)

“…excitement and pleasure in science derive not so much from achieving the final explanation as from discovering the fascinating range of new phenomena to be explained” (Baker and Komatsu, 1999).”

Networks on Venus

The Magellan spacecraft acquired SAR (Synthetic Aperture Radar) images of venusian surfaces at a spatial resolution range of about 100 m per pixel.

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Frozen Seas on Mars and Earth


Posted by
Dr. Matt Balme, Open University, UK. 

(Re-posted from IAG Image of the Month, October, 2007)

Elysium Planitia

Images of the ‘frozen sea’ on Mars (a,b) from the High Resolution Stereo Camera of the ESA Mars Express Mission, and pack-ice (c) in the terrestrial Antarctic.

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Vir-Ava Chasma, Venus

Posted by Les Bleamaster, Planetary Science Institute, Tucson, Arizona, USA.

(Re-posted from IAG Image of the month, July 2007)

This false color, three-dimensional perspective view over the Turan Planum of Venus shows the interaction of tectonic structures and volcanic processes along chasmata or “rifts.”

venus

Foreground is approximately 400 km, with a vertical exaggeration of 8x.

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Volcanic Regions on Venus

Posted by Les Bleamaster, Planetary Science Institute, Tucson, Arizona, USA.

(Re-posted from IAG Image of the Month, May, 2007)

Synthetic Aperture Radar (SAR) images from NASA’s Magellan mission to Venus (science mission complete in 1994) show two distinctly different volcanic regions within only a few hundred kilometers of each other. venusgeo (more…)

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