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The freshest outflow channel, Floods in Athabasca Valles
SigurRosFan
post Apr 9 2006, 11:33 AM
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Release date: April 03, 2006

- http://themis.asu.edu/features/athabascafloods

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Based on the counts, however, the valley is between 2 million and 30 million years old. If true, that makes it the youngest outflow channel on Mars.

Estimates of the volume range from 10,000 to 10 million cubic meters per second. For comparison, the Mississippi River's flow averages 17,000 cubic meters per second.
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Athabasca Valles and Cerberus Fossae are one of my interesting places on Mars. I'm searching for images of this rootless cinder cones in the valley.


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Bob Shaw
post Apr 9 2006, 11:47 AM
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QUOTE (SigurRosFan @ Apr 9 2006, 12:33 PM) *
Athabasca Valles and Cerberus Fossae are one of my interesting places on Mars. I'm searching for images of this rootless cinder cones in the valley.


I think there were some good MGS images of them. It's a fascinating locale all round!

Bob Shaw


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Guest_Richard Trigaux_*
post Apr 9 2006, 12:02 PM
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This flow looks like if it was guided by one of these numerous low ripples we see in many parts of Mars, and wich ressemble cooling ripples we see on the Moon "seas". In the case of the Moon, these ripples are usually interpreted as consequence of the cooling of large and deep lava flows. But On Mars?


What is stunning is that this water seems to have erupted from a fault in the north east of athabasca valley. If you look at the infrared map (Google Mars, search for Athabasca) it is clear that flow marks are flowing out of it. At first these flow marks are just changes of colour on the ground, without visible erosion, but after erosion marks are very visible. Perhaps it is because if flowed first on rocky terrain (lava flows) and after on a sandy terrain. And again, the flow rate was very large, but during a short time.


That such a large water flow is getting out of the ground in a place where there is a large geological feature contradicts the usual model of a large watertable provoking water eruptions. This water seems to come out of much deeper in the ground, some kind of water volcanism. And the fault too must be recent and active. It seems to be a long one (hundreds of kilometres) and recent and active.


Also clearly visible in the bottom of the image are traces of a broken ice layer. Most probably there was ice forming on a mud flow (at this place the flow was calmer, and likely it gathered much of martian dust to form mud). Further movements broke the ice layer until all the thing settled with freezing. Then the pure ice sublimated, lefting these drawings where mud appeared between ice blocks.
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SigurRosFan
post Apr 9 2006, 12:53 PM
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Additional (2002) article:

- http://www.marstoday.com/news/viewpr.html?pid=7466 (Floods at Mars' Equator Are Recent, UA Scientists Say)

Cerebus Fossae and Athabasca Valley:


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Guest_Richard Trigaux_*
post Apr 9 2006, 04:16 PM
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QUOTE (SigurRosFan @ Apr 9 2006, 12:53 PM) *
Additional (2002) article:

- http://www.marstoday.com/news/viewpr.html?pid=7466 (Floods at Mars' Equator Are Recent, UA Scientists Say)


Did you noticed that, in the fig 1 of this article, there is a fine dark line stretching from, grossly the top left corner to the center. You need to zoom on it with a drawing software (ftp://pirlftp.lpl.arizona.edu/pub/dburr/GRL/, figure1.tiff) and you see that it goes all through the mesa untill the right bottom corner, and that other are visible, parallel to the first. Only possible explanation: tectonic faults. And recent ones. Others seems to crisscross the firsts at low angles. They could not form before the channels.


THERE ARE RECENT TECTONIC FAULTS ON MARS.
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helvick
post Apr 9 2006, 04:54 PM
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QUOTE (Richard Trigaux @ Apr 9 2006, 04:16 PM) *
THERE ARE RECENT TECTONIC FAULTS ON MARS.

These look like faults alright but I assume that "tectonic faults" means large scale crustal movements and I'm not so sure that we can use that sort of description for this. Of cource the faulting might be crustal movement and that might have caused the outflow but the reverse might be true - the outflow might have led to localised faulting and might have a very different root cause.
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lyford
post Apr 9 2006, 05:25 PM
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This image is also fascinating:

Streamlined mesa with similar orientation and terracing. Crater sits at upslope end; mesa formation is hypothesized to be by deposition in its lee during flood flow
It sure looks like the crater filled and then the walls breached and drained with the flow.... That's a lot of water!


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Guest_Richard Trigaux_*
post Apr 9 2006, 06:29 PM
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What is much astonishing too is that there was lava AND water flowing out from the same hole. As if the marsian volcanoes had water as a common type of eruption. On Earth we don't have water volcanoes, but we have mud volcanoes which could create flow traces. But usually the mud is too thick to give flow traces like Athabasca. And anyway mud volcanoes are very generally not connected to lava volcanoes. There are some exception though, but of small size.

Massive water floods on mars are generaly explained as the merting of large underground ice bodies or watertable. Eventually the eruptions would be driven by dissolved gasses. But I wonder if there would not be on Mars mantellic water. We know on Earth that there is a small percentage of water in the mantle (add to this that some volcanoes are fed with marine sediments soaked with water). So most lavas contain water mixed in, a fact which is possible due to the very high pressure into the depths of the Earth. When a mixture of water and lava comes near the surface, usually the separation occurs during the eruption, giving violent explosions. In some case it is a mixture of steam and dust which erupts.

Would not be possible that, on Mars, the separation could take place much deeper, when the lava gets solidified into deep magma chambers? If this could happen, it would give a subterannean body of hot water. With a connection to lava volcanoes.

But if so, this hot water (300-500C) would boil when erupting, lefting only a residue of cold water. The vent would look like a maar (crater without a cone, formed by some explosive eruptions). A large part of the eruption would give a temporary atmosphere to Mars, with rain and snow everywhere on the planet. As I explained in another thread, this would explain the large flow channels in the southern highlands, as well as the small gullies seen on many slopes.
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