I wasn't going to go that far and speculate what gases they could be, if these are truly gas escape structures. The link you provided to the article about the similar structures in Colorado refers to the gas probably being methane. However, I assume any type trapped gas could cause these structures. It is certainly suggestive that the color of the rock they just drilled into indicates a reducing environment. The same type of environment that methane is found on Earth today.

It's also wise to remember that water & of course CO2 sublimate at Mars surface pressure.

Jury's still out on what these are, but if they are in fact gas escape features then those two substances would be the most likely candidates by a wide margin.

Don't we also sometimes see these structures in vertical surfaces, perpendicular to the bedding plane? If so, they are more likely to be the rims of small concretions, as has been discussed previously, than gas escape structures.

John

fredk: the tardy images are now there--I was still only looking back 60 days.

Possibly not at the time these features formed. There are lots of Earth analogues that could explain these features, including the suggested gas release, concretions or nodules. Diapirs or armored mud balls would be a good fit for the large examples seen.

Anyone have a vacuum chamber and some clay-y mud?

Also I have to wonder what would happen to a carbonate / mud mix when sulfuric acid percolates through it. I would think that CO2 would bubble out it...

I gotta side with John: Concretion 'craters' are a far more likely explanation.

Consider: Escaping gas bubbles would only be possible in a malleable--presumably wet--surface if the atmosphere was considerably different than that of today. Very well, but how would such features be preserved for a couple of billion years in such an apparently pristine fashion given such an atmosphere with stronger winds?

We have substantial evidence that wind erosion is a modern process on Mars, albeit operating much more slowly then on Earth. Therefore, these features are more likely to be artifacts of previous concretions that formed in a wet environment and weathered away faster then the substrate in which they were embedded due to compositional differences (possibly moisture content) as the planet's climate evolved.

Gotta wait for the experts to officially weigh in, but that's the hypothesis that makes the most sense to me right now.

INTERACTIVE panorama from Mars: Curiosity Rover's Self Portrait at "John Klein" Drilling Site:
http://www.360cities.net/image/mars-panorama-curiosity-solar-day-177





This self-portrait of NASA's Mars rover Curiosity combines 66 exposures taken by the rover's Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity's work on Mars (Feb. 3, 2013).

At the bottom of this panorama is the hole in a rock. The drilling took place on Feb. 8, 2013, or Sol 182, Curiosity's 182nd Martian day of operations.

The images for full panorama obtained by the rover's 34-millimeter Mast Camera. The mosaic, which stretches about 30,000 pixels width, includes 113 images taken on Sol 170 and an additional 17 images taken on Sol 176.

Please don't hesitate to share it

First BW panorama of Mars from Curiosity rover got more that 1,700,000 views from August 2012:
http://www.360cities.net/image/curiosity-rover-martian-solar-day-2

Perfect!
Getting Mars Street View a century early, what's not to like?

Entirely consistent with what John Grotzinger has said about this area though. And if these structures can survive in a very active Earth environment, i'm pretty sure they could do the same on Mars.

Wow 360pano.eu, That took my breath away! Very Superb work!

Tht is just awsome - definitely the closest thing to being there particularly if you display on HD widescreen TV

Amazing work !

First post.

360pano.eu: Wow, that is fantastic!

All: Has there been any hint from the MSL team that the "shiny prong" will be a ChemCam target? Some closer MAHLI shots of it would be nice too.

I think it's too far away for ChemCam from here, and might be tricky to reach, certainly for MAHLI. But there may be others.

Phil

It appears to be out of range for the laser, at around 9 metres vs laser range 7 metres. I guess chemcam imaging could be done.

To get any benefit from mahli, we'd have to drive a lot closer, and it doesn't look like that's going to happen soon.

The bigger question is: does the team think it's worth the effort?

Edit: scooped by Phil!