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

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 4 Dec 2012 11:15:59 -0800 (PST)
Message-ID: <201212041915.qB4JFxCq020297_at_zagami.jpl.nasa.gov>


Alan Fischer
Public Information Office
Planetary Science Institute
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

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

Mark V. Sykes
sykes at psi.edu

Received on Tue 04 Dec 2012 02:15:59 PM PST

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