You have one excellent example there, the bottom part as seen on this image have moved to the left, as seen in the center and near bottom left on that image.

It would be nice if you provided us with information of the location and scale of that image.

Of course I can give you the link. It's a HiRISE image taken in Ius Chasma. The link of the observation page is: http://hirise.lpl.arizona.edu/TRA_000823_1720

There's a big difference between "tectonics" and "plate tectonics." Nobody will dispute the claim that there has been tectonic activity on Mars, the brittle deformation of rocks in response to geologic stresses. Various events on Mars cause the kinds of stresses that result in tectonic deformation. Things like massive Tharsis volcanism loading the crust, making it bend downward and flex outward, caused a lot of fracturing etc. Things like true polar wander, where the outer rigid shell of Mars may have moved independently of the core as a result of uneven mass distrubution (again, Tharsis) making it rotationally unstable until the outer shell rotated to put the center of Tharsis on the equator. Since spinning planets are fatter through the middle than pole-to-pole, this motion would've required a shape change of the outer shell that would have caused major stresses that would have caused tectonic deformation. On a smaller scale, you see wrinkle ridges throughout volcanic plains that result from the downwarping of the crust after loading with the weight of those lava flows.

"Plate tectonics" is a specific theory of how a planet redistributes its internal heat through the convective motion of a mantle that behaves as a fluid, coupled to a rigid, brittle outer shell, such that the shell breaks into large plates and nearly all tectonic activity on the planet is concentrated at plate boundaries, which are (to a first-order approximation) also the boundaries between mantle convection cells. To say that plate tectonics is happening, you have to show that tectonic activity is only occurring along plate boundaries, and that it results from convection in the mantle.

I was just preparing the exact same post, Emily. Tectonics are evident on every body we've looked at closely in the inner solar system. You can find such fault movements (I want to call it a strike/slip fault, but I'm not certain enough of my terminology to say that definitively), as shown in the Ius Chasma image above, on the Moon and Mercury fairly easily, if you know what to look for. I believe there are similar features on Venus, as well. And wrinkle ridges are quite common everywhere that the weight of enormous lava flows has put pressure on the underlying crust.

But the only place we've seen actual evidence of plate tectonics is here on Earth. At least, thus far.

-the other Doug

Hi again,

I perfectly understand what Emily and Doug want to say, and they are completely right. Of course there is a difference between tectonics and plate tectonics. But, why did I choose this image instead of using one of the thousand pictures of faults in Mars as a point to plate tectonics? Because it's inside the Valles Marineris system, and if we accept the idea that Valles Marineris is a martian rift system we can say that is a divergent margin between two plates.

Of course, I'm not saying that there is a plate tectonics like the one we have in Earth (we don't see, for example, a bimodal height distribution between continental crust and other kind of crust, except the difference of Northern highlands and Sourthern highlands), but accepting the idea of the rift system I think it's necessary to accept the presence of convective motion under the crust to create a rift system.

But, as everything in Mars, we need more data to create a better picture of it's crustal structure and thermal evolution. Maybe Mars lost a very important quantity of heat through vulcanism at a very high rate and wasn't able to develop a plate tectonics like the one we are used to.

Now, *my* best understanding of the rift systems on Mars is that they were created as the weight of the Tharsis Bulge distorted and cracked the underlying crust. No mantle convection or crustal plate processes are required for a rift system to form, just enough weight on the crust to make it crack apart around the heavy weight that's distorting the crust in the first place.

What I have always found interesting is that it appears only the crust to the south and east of Tharsis cracked under the weight. The crust to the north of the bulge doesn't seem to show the same kind of crustal cracking that formed the rift systems.

-the other Doug

Of course, Tharsis Bulge was also responsible, but I think there is also necessary to have some ascending hot material coming from under the crust. I don't want to say that there is a lot of effusive volcanic activity in the rifts, of course, as there is no proof of that. Maybe a mixed mode rifting in which crustal extension due to Tharsis Bulge and a high thermal regime was able to form the rift.

That's my modest opinion, I wish we had more data (or even a field trip!)

Greetings

This is one of the reasons I'm so excited about getting some actual heat flow information from Mars, so we can begin to intelligently model Mars' thermal history.

-the other Doug

That makes good sense. So the Tharsis volcanic chain could be a result of this crustal movement (as opposed to plate migration as on Earth or the concept that the hot spot moved beneath a stable crust)? If so wouldn't the reasonably short chain length indicate that the Tharsis Bulge was close to the then equator and so the crustal rotation would have been fairly small?

I haven't found mentionned here this article of Nature geoscience, so I go for a fisrt post

Planetary science: Uninhabitable martian clays?

Brian Hynek
Nature Geoscience
(2012)
doi:10.1038/ngeo1560


Abstract :
Clay minerals on Mars have been interpreted as an indication for a warm, wet early climate. A new hypothesis proposes that the minerals instead formed during brief periods of magmatic degassing, diminishing the prospects for signs of life in these settings.

apparently the author identified in Mururoa Atoll basalts (famously drilled and investigated during french nuclear testing experiments), clays mineral formed not by weathering, but by magmatic degassing (with of course water in magma gas ). This indicate an other possible way to produce clays, and deacrease the automatic link for martian geology beetween clays and liquid water.

A small meteorite found in Sahara might be from the crust of the planet and from the Amazonian period.

NWA 7034 contains somewhat more water than what is usual for Martian meteorites, also organics of a type that suggest the molecules have been created in a non-biological process.

Carneige institute for Science

They think most other martian meteorites came from the mantle?!

Re: "...researchers have identified a new class of Martian meteorite that likely originated from Mars’s crust."

I think the likeliest interpretation is that of all meteorites likely originating from Mars's crust, this represents a new class.

I think not, mantle material would be something. =) I happened to mention that word 'crust' since the text is several times are phrased in a way that it make a point of: '"It is the first link thus far of any meteorite to the crust."
Without making the matter clear if they identified similar volcanic crust material on Mars from orbit, or something else.

The second part about the organic molecules are another piece of the puzzle, they do not say so directly only referring to "other Martian meteorites" but it have been noted that the magnetites found in AH 84001 could have worked as a catalyst for the organic macromolecules found in that meteorite. Now in the case of NWA 7034 it is feldspar and iron oxide. This work is important since such non-biological processes that produce macromolecules have implications for both current (MSL with SAM) or future instruments flown to Mars.

This is a little clearer, even coming from Faux Scientist:
http://www.newscientist.com/article/dn2304...for-longer.html

"This suggests the known meteorites came from deeper inside the Red Planet." -- I guess that means below any layer that's weathered?