[meteorite-list] Mars Odyssey THEMIS Images: October 4-8, 2010

[MEM]

The term" rift valley/rift" is somewhat subjective as a rift proper is normally 
associated with plate movement but this example in not from the "tectonic plate 
movement" we are familiar with on earth. This valley resulted from a "tectonic 
process". Specifically a branch of tectonic study called thrust/contraction 
tectonics <http://en.wikipedia.org/wiki/Thrust_tectonics>

The feature is a graben . A graben <http://en.wikipedia.org/wiki/Graben> is type 
of fault feature where contraction( vs compression) pulls perpendicular to to 
the linear features and a block of landscape drops in relation to the 
surrounding.  On each side of the graben will be steep sloped escarpments. A 
horst is the highland between two grabens that remained at the same elevation of 
may have been up-thrusted.

In the example you posted the movement was a few inches/feet left and right of 
the escarpments( parallel lines) as well as a downward movement of the valley 
floor a distance I am unable to determine from the photo but could have been 
tens to hundreds of feet.  This is not a slip strike fault where the opposite 
sides are displaced laterally.

 I've read recently about contraction of the lunar crust owing to overall 
cooling producing these features.  On a lunar-wide basis when the formerly 
liquid mantle transitioned to a solid the sum total of all the nanometer sized 
compression of the space between molecules is seen on the surface as these 
grabens.  The link above shows a substantial graben on the moon.  


To read about recent graben formation on earth you might google the 1811-1812 
New Madrid Earthquare or<http://en.wikipedia.org/wiki/New_Madrid_Seismic_Zone>  
and the formation of the ReelFoot lake in western Tennessee. That area lies on a 
failed rift where North America almost split.  I think the Reelfoot Lake basin 
came from a graben drop of only about 6 ft but left a lake of 30 square miles 
and about 3 ft /1meter deep.

Elton



----- Original Message ----
> From: Jerry Flaherty <grf2 at comcast.net>
> To: Ron Baalke <baalke at zagami.jpl.nasa.gov>; Meteorite Mailing List 
><meteorite-list at meteoritecentral.com>
> Sent: Fri, October 8, 2010 8:22:25 PM
> Subject: Re: [meteorite-list] Mars Odyssey THEMIS Images: October 4-8, 2010
> 
> A little geologic help please.
> In the image "Alba Mons Tectonics" could  someone elucidate and elaborate on 
> the tectonic features shown.
> Are we  looking at a rift at one or both parallel "lines" depicted and if so:
> are the  lines related
> what is the direction of the movement
> what specific features  demonstrate this movement
> any other features which demonstrate tectonic  activity that I'm not seeing
> Thanks to any respondents in advance
> Jerry  Flaherty
> --------------------------------------------------
> From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
> Sent:  Friday, October 08, 2010 5:55 PM
> To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
> Subject:  [meteorite-list] Mars Odyssey THEMIS Images: October 4-8,  2010
> 
> >
> > MARS ODYSSEY THEMIS IMAGES
> > October 4-8,  2010
> >
> > o Wind Erosion (04 October 2010)
> >   http://themis.asu.edu/zoom-20101004a
> >
> > o Pavonis Mons (05 October  2010)
> >  http://themis.asu.edu/zoom-20101005a
> >
> > o Wind  Texture (06 October 2010)
> >   http://themis.asu.edu/zoom-20101006a
> >
> > o Central Peak Crater (07  October 2010)
> >  http://themis.asu.edu/zoom-20101007a
> >
> >  o Alba Mons Tectonics (08 October 2010)
> >   http://themis.asu.edu/zoom-20101008a
> >
> >
> > All of the THEMIS  images are archived here:
> >
> >  http://themis.asu.edu/latest.html
> >
> > NASA's Jet Propulsion  Laboratory manages the 2001 Mars Odyssey mission
> > for NASA's Office of  Space Science, Washington, D.C. The Thermal Emission
> > Imaging System  (THEMIS) was developed by Arizona State University,
> > Tempe, in co.oration  with Raytheon Santa Barbara Remote Sensing.
> > The THEMIS investigation is  led by Dr. Philip Christensen at Arizona State
> > University. Lockheed  Martin Astronautics, Denver, is the prime contractor
> > for the Odyssey  project, and developed and built the orbiter. Mission
> > operations are  conducted jointly from Lockheed Martin and from JPL, a
> > division of the  California Institute of Technology in Pasadena.
> >
> >
> >
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