This blog provides commentary on interesting geological events occurring around the world in the context of my own work. This work is, broadly, geological fluid dynamics. The events that I highlight here are those that resonate with my professional life and ideas, and my goal is to interpret them in the context of ideas I've developed in my research. The blog does not represent any particular research agenda. It is written on a personal basis and does not seek to represent the University of Illinois, where I am a professor of geology and physics. Enjoy Geology in Motion! I would be glad to be alerted to geologic events of interest to post here! I hope that this blog can provide current event materials that will make geology come alive.

Banner image is by Ludie Cochrane..

Susan Kieffer can be contacted at s1kieffer at gmail.com

Thursday, March 31, 2011

Mud volcanoes on Mars?

Mounds on Mars in Acidalia Planitia, Mars. From
Oehler and Allen, Evidence for pervasive mud volcanism
in Acidalia Planitia, Mars, Icarus, 208(2),pp. 636-657, 2010.

Since the days of Viking exploration, there has been speculation that mud volcanism occurs on Mars. Candidate features populate the Northern Plains (see review in the paper referenced in the figure caption to the left).  On Earth, mud volcanism is triggered by tectonic compression or generation of hydrocarbons (esp. methane, CH4).  Neither process appears to be prominent on Mars.  Mechanisms that have been proposed include: (1) dewatering of debris flows; impact-related, seismic shaking causing liquefaction; sedimentation with compaction and degassing; and sublimation of CH4 or CO2 clathrates.  The mounds in Acidalia are on a very large scale, and Oehler and Allen favor an explanation that includes the basin's unique geologic setting.  Acidalia Planitia sits where large quantities of sediments were deposited from outflow channels.  It was a "depocenter" for accumulation of mud and fluids from this sedimentation.  The mounds may be attributable to large overpressure developed in response to the rapid outflow deposition, "perhaps aided by regional triggers for fluid expulsion related to events such as tectonic or hydrothermal pulses, destabilization of clathrates, or sublimation of a frozen body of water."  They could account for a significant release of gas, and the process may have created long-lived conduits for upwelling groundwaters.

In a recent article in Earth and Planetary Science Letters (v. 304, pp. 511-519, 2011), Pondrelli et al. reported on possible mud volcanoes within Firsoff impact crater. The mounts are on the crater floor, and appear as isolated or composit cones 100-500 m in diameter, and tens of meters high.  More than 1/3 have subcircular depressions on their apices, 5-39 m deep, interpreted as vents. The mounds themselves are meter-sized boulders embedded in a finer-grained matrix, a mud breccia. The mounds are located on or near faults and are aligned with fractures, suggesting larger pathways for fluid migration along faults related to the impact that produced the crater. The authors speculate that methane was involved in the process of forming the mounds.


Anonymous said...

It's amazing to see other people actually interested in this stuff. I'm part of a research team studying Firsoff and found this blog entry completely by chance while looking for some Earth analogues of mud volcano mounds for our upcoming conference in Melbourne, Australia. Great job on the summary there, I might add. It's cool to find other people actually interested in the research that we're doing, beside the ones also working on the same thing. It gives one a sense of accomplishment, rather than the regular shrugs and bewildered faces one gets when trying to explain impact-generated hydrothermal systems in a high-pitched, excited voice to a regular, very passive person. Well...that's it for that rant and good on you for the enthusiasm shown! :D


Susan W. Kieffer said...

Thanks for the interest and compliment, Alice!