[meteorite-list] Vast Systems of Ancient Caverns on Mars May Have Captured Enormous Floodwaters

[Ron Baalke]

NEWS RELEASE FROM THE PLANETARY SCIENCE INSTITUTE

FROM: 
Alan Fischer
Public Information Office
Planetary Science Institute
520-382-0411
520-622-6300
fischer at psi.edu

Vast Systems of Ancient Caverns on Mars May Have Captured Enormous Floodwaters

Dec. 4, 2012, Tucson, Ariz. -- An international research team led by the Planetary 
Science Institute has found evidence that indicates that approximately 
2 billion years ago enormous volumes of catastrophic floods discharges 
may have been captured by extensive systems of caverns on Mars, said PSI 
Research Scientist, J. Alexis Palmero Rodriguez.

Rodriguez and the research team came to this conclusion after studying the terminal 
regions of the Hebrus Valles, an outflow channel that extends approximately 250 
kilometers downstream from two zones of surface collapse. 

The Martian outflow channels comprise some of the largest known channels in the 
solar system. Although it has been proposed their discharge history may have once 
led to the formation of oceans, the ultimate fate and nature of the fluid discharges 
has remained a mystery for more than 40 years, and their excavation has 
been attributed to surface erosion by glaciers, debris flows, catastrophic 
floodwaters, and perhaps even lava flows, Rodriguez said.

The PSI-led teams' work documents the geomorphology of Hebrus Valles, a Martian 
terrain that is unique in that it preserves pristine landforms located 
at the terminal reaches of a Martian outflow channel. These generally 
appear highly resurfaced, or buried, at other locations in the planet. 
Rodriguez and his co-authors propose in an article titled "Infiltration 
of Martian overflow channel floodwaters into lowland cavernous systems"
published in Geophysical Research Letters that large volumes of catastrophic 
floodwaters, which participated in the excavation of Hebrus Valles, may 
have encountered their ultimate fate in vast cavernous systems.

They hypothesize that evacuated subsurface space during mud volcanism was an 
important process in cavern development.  Mud volcanism can expel vast 
volumes of subsurface volatiles and sediments to the surface. But because 
evacuation of subsurface materials generally occurs within unconsolidated 
sediments resulting caverns are transient and mechanically highly unstable. 

However, the investigated Martian caverns appear to have developed within 
permafrost, which at -65 degrees Celsius (-85 degree Fahrenheit) - a 
typical mean annual surface temperature for the investigated latitudes 
- has a mechanical strength similar to that of limestone. Limestone 
rocks host most of the terrestrial cavern systems.

Possible cavern have been recently identified on Mars and their existence 
has caught much scientific and public attention because of their potential 
as exobiological habitats. However, their age and dimensions remain 
uncertain. The discovery of vast caverns that existed in ancient periods of 
Mars shows that these habitats may have in fact existed during billions of 
years of the planet's history, Rodriguez said.

PSI Senior Scientist Mary Bourke and Research Scientist Daniel C. Berman 
are co-authors on the paper.

This research was funded by a grant to PSI from the NASA Mars Data Analysis 
Program.


CONTACT:
J. Alexis Palmero Rodriguez
Research Scientist 
alexis at psi.edu


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sykes at psi.edu

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