Eruptions of mud on Mars in the past ?

Exploration of Mars has revealed the presence of large outflow channels which have been interpreted as the products of catastrophic flood events during which a large quantity of water was released from the subsurface. The rapid burial of water-rich sediments following such flooding may be an ideal setting for sedimentary volcanism, in which mixtures of rock fragments and water erupt to the surface in the form of mud.

boue mars web 400px
An individual mud flow outgoing from a ‘gryphon’
on top of Dashgil volcano in Azerbaijan (39°59′48″N, 49°24′11″E)
© Petr Brož

Tens of thousands of conical hills populate the northern lowlands and other places on Mars. The origin of these structures has been widely debated. It has been proposed by many that these cones may represent the surface expressions of such mud eruptions. However, it is difficult to determine whether these cones are related to mud extrusions or not, partly because the behaviour of extruded mud under martian surface conditions was poorly constrained.

A European team of scientists decided to close this gap in our knowledge. They performed a set of experiments inside a low-pressure chamber during which a water-rich mud was poured over a cold sandy surface. The setup for the experiments was designed to mimic the hostile conditions on Mars to reveal how the instability of water within the mud changes its behaviour. They found that mud exposed to atmospheric pressure as low as that on Mars would propagate in a similar way to lava flows found in Hawaii or Iceland (so-called pahoehoe flows).

"This is a very exciting and unexpected result. We have a tendency to expect that geological processes, like mud movement, would be operating elsewhere in the Solar system in a similar fashion as on Earth. This is based on our everyday experience; however, our experiments clearly show that in reality, this simple process which we all know from our childhood would be very different on Mars". said the research lead author Dr. Petr Brož from the Czech Academy of Sciences.

The observed phenomena are related to the fact that the martian atmosphere is very thin, ~150 times thinner than on Earth. This means that liquid water is not stable, both boiling and evaporating. Evaporation and boiling remove heat from the mud, causing it to freeze.

"These observations could revolutionise our interpretation of many surface features mapped on the martian surface" commented co-author Dr. Susan Conway from the CNRS in France.

The team showed that the experimental mud flows propagate like terrestrial pahoehoe lava flows, with liquid mud spilling from ruptures in the frozen sandy crust, then refreezing to form a new lobe. This finding suggests that mud martian mud volcanoes may be substantially different in shape from terrestrial ones. This work has wider implications, since similar processes may also apply to cryovolcanic extrusions on icy bodies in the Solar System.

 

> Référence : Experimental evidence for lava-like mud flows under Martian surface conditions, Petr Brož1*, Ondřej Krýza1, Lionel Wilson2, Susan J. Conway3, Ernst Hauber4, Adriano3 Mazzini5, Jan Raack6, Matthew R. Balme7, Matthew E. Sylvest7 and Manish R. Patel7,8, Nature Geoscience

1 Institute of Geophysics of the Czech Academy of Sciences, Boční II/1401, 141 31, Prague, Czech Republic, 2 Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK, 3 CNRS UMR-6112 LPG Nantes, France, 4 Institute of Planetary Research, DLR, Rutherfordstr. 2, 12489, Berlin, Germany, 5 Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Norway, 6 Institut für Planetologie, Westfälische Wilhelms-Universität Münster, Germany, 7 School of Physical Science, STEM, The Open University, Milton Keynes, UK Open University, Milton Keynes, United Kingdom, 8 Space Science and Technology Department, STFC Rutherford Appleton Laboratory, Oxford, UK

 

> Contacts :

Susan Conway, CNRS Research Scientist CNRS LPG - susan.conway@univ-nantes.fr - Phone: +33 (0)2 76 64 51 53
Stéphanie Beaunay, communication manager – stephanie.beaunay@univ-nantes.fr – Phone: +33 (0)2 51 12 52 67

 

More informations

> Video online

> Press release CNRS