Mud flows exposed to the low atmospheric pressures found on Mars will behave similar to lava flows in Hawaii or Iceland, also known as pahoehoe flows, according to new research.
This image from NASA’s Mars Reconnaissance Orbiter (MRO) shows a hill with a central crater. Such features have been interpreted as both mud volcanoes (really a sedimentary structure) and as actual volcanoes (the erupting lava kind). They occur on the floor of Valles Marineris below a closed topographic contour that could have held a lake, and the compaction of wet sediments may have created mud volcanoes. Image credit: NASA / JPL-Caltech / University of Arizona.
Tens of thousands of volcano-like landforms dot the surface of Mars. Some have been attributed to magmatic volcanism.
These landforms occur in terrains covered by sediments thought to have been deposited by ancient floods, and the rapid burial of wet sediments could have resulted in mud volcanism.
However, little is known about how mud would flow on Mars, due to the complexity of performing these experiments in the lab.
Dr. Petr Brož from the Institute of Geophysics of the Czech Academy of Sciences and colleagues decided to address the knowledge gap and investigate the lava-like flows on Mars.
The researchers poured a water-rich mud over a cold sandy surface in the low-pressure Mars Chamber at the Open University, UK, and multiple cameras recorded the results.
Their experiments were designed to simulate the hostile Martian conditions revealing how the instability of water within the mud changes the mud’s behavior.
They found that under the low atmospheric pressure and low temperatures of the Martian surface, mud flows would end up looking similar to pahoehoe flows on Earth.
“Most people assume hot magmatic volcanic activity created all the features we see on Mars, but it looks like some of them may in fact be due to mud volcanism — meaning a potentially different geological history for Mars in terms of assumed volcanic activity,” said Dr, Manish Patel, a planetary scientist at the Open University.
“This is a great example of how a seemingly bizarre idea for an experiment in a lab can revolutionize our interpretation of the features on another planet.”
Water is not stable and begins to boil and evaporate under Martian surface pressure. The evaporation removes latent heat from the mud, eventually causing it to freeze.
The team showed that the experimental mud flows spread like terrestrial pahoehoe lava flows, with liquid mud inside the flow spilling out from ruptures in the outer frozen muddy crust, then refreezing to form a new flow lobe.
This finding suggests that mud volcanism can indeed operate on the surface of Mars.
“This is a very exciting and unexpected result,” Dr. Brož said.
“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 experiences.”
“However, our experiments clearly show that in reality, this simple process which we all know from our childhood would be very different on Mars.”
A paper on the findings was published in the journal Nature Geoscience.
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P. Brož et al. Experimental evidence for lava-like mud flows under Martian surface conditions. Nat. Geosci, published online May 18, 2020; doi: 10.1038/s41561-020-0577-2
