MSL Sol 514: Mineral Veins Or Fossilized Crinoid Columnals?

iRoyalty
reply to post by jeep3r

 

This is what we should be keeping an eye out for, people keep claiming every rock is a skeleton, or a fossilised monkey or an (insert earth creature structure here).

Instead, we should be looking for evidence of plant life, that would be a sure sign that there is, was, or could have been life on Mars.

thats correct, all these claims of fossils and yet no sigh of a planet wide ecosystem to support it. as yet no biological by-products of such ecosystem has been found, no limestone, chalk, coal tar or oil and similar hydrocarbons or even biological methane.

reply to post by jeep3r


Haven't seen this cute little animation posted yet (source: NASA/JPL):


Somehow fits well to the mounting evidence for habitable environments incl. lakes & conditions for microbial life at different locations on Mars.

iRoyalty
reply to post by jeep3r

 

This is what we should be keeping an eye out for, people keep claiming every rock is a skeleton, or a fossilised monkey or an (insert earth creature structure here).

Instead, we should be looking for evidence of plant life, that would be a sure sign that there is, was, or could have been life on Mars.

Could a volcanic eruption on Earth (say Vesuvius) have blown rocks, statuettes, and pottery out of Earth's atmosphere, into space where it eventually landed on Mars?

reply to post by stormcell



*sarcasm on*

Well, unless a city was built directly on top of that volcano I'd say 'no' ... and even if, would that debris make it into space? Then all would depend on size, shape, speed and rotation of those hypothetical 'chunks' upon reentry. Even Curiosity needed a heatshield!

My guess is that all arguments would become obsolete when considering the final impact, but interesting that you were thinking about the possibility of that happening!

*sarcasm off*!

Being a geologist myself we are often taught not to jump to conclusions until we've held the rock in our hands, but given the likelihood of that happening any time soon I feel relatively safe in saying that they look awfully like plagioclase feldspar phenocrysts set within a largely aphanitic groundmass. That would make this rock extrusive volcanic in origin, however the presence of such large crystals would mean that this melt was erupted during the process of crystallisation (as plagioclase is one of the first minerals to crystallise).

reply to post by NoExpert


kinda like these ones ?

pics

hmm just found an excellent rock viewer, shame nasa didn't have a robotic arm to take pictures from 4 sides, might have a chance to create 3d rocks like this one

3drock



funBox

reply to post by NoExpert


Thanks for the explanation.

Now, one question: having said that about the rock, what do you think about finding a rock like that in a place like the one Curiosity is, a supposed dry lake? Thanks in advance.

funbox
reply to post by NoExpert

 

kinda like these ones ?

pics

Precisely like that, though the view there is down the microscope so the structures in that image are not on the same scale as the images taken by Curiousity.

Some macroscopic examples from Earth would be:

This and this.

ArMaP
Thanks for the explanation.

Now, one question: having said that about the rock, what do you think about finding a rock like that in a place like the one Curiosity is, a supposed dry lake? Thanks in advance.

No worries. As for the fact that it's not the sort of rock we'd expect to find in a sedimentary environment, I really couldn't comment with any certainty given the amount of information we have available. The MAST cam images don't show if the outcrop is in situ or not which is the most important factor.

I could list some possible explanations, for example it could very well just be a large boulder of ejecta that has landed in Gale crater. It could be the result of an impact induced melt (unlikely in my opinion given the size of those phenocrysts), it could be the exposed surface of the environment present before the sedimentary facies began to dominate, etc...

But that's the annoying thing about having to do geology from a distance. A lot of 'could' and not enough certainty.

reply to post by NoExpert


Thanks for your helpful comments, NoExpert ... it's incredibly useful for us to have a geologist like yourself among us. Your expertise will certainly help examining the martian terrain and features in threads like these with professional insight (even if that means that we might need to 'ground' some of our interpretations & theories).

By the way: do you happen to have an opinion on this thread by fellow ATS member Arken or other formations like those found in this OP (see mosaic on first page)? Are any of these especially intriguing to you?

Thanks again & I'm very much looking forward to seeing you around in this forum!

NoExpert
Being a geologist myself we are often taught not to jump to conclusions until we've held the rock in our hands, but given the likelihood of that happening any time soon I feel relatively safe in saying that they look awfully like plagioclase feldspar phenocrysts set within a largely aphanitic groundmass. That would make this rock extrusive volcanic in origin, however the presence of such large crystals would mean that this melt was erupted during the process of crystallisation (as plagioclase is one of the first minerals to crystallise).

Would that account for the fact that the apparent "crystals" are clearly not aligned, and that some of them are actually overlapping?

Blue Shift
Would that account for the fact that the apparent "crystals" are clearly not aligned, and that some of them are actually overlapping?

Absolutely. You need to have in mind that the rock surface is essentially a 2D representation of a 3D system. Crystal growth often isn't linear and ordered, rather it is limited to interstitial spaces between other nucleating crystals. Intergrowth and twinning are very common. I've whipped up a rather crude image in paint that I hope demonstrates how the various orientations of crystals can produce an 'interlocking' pattern at the surface level of the rock (in this case the red line), despite all being at different orientations to one another.

Alternatively just take a look at the examples from our own planet to see the same interlocking texture. Here and here.

jeep3r
reply to post by NoExpert

 

Thanks for your helpful comments, NoExpert ... it's incredibly useful for us to have a geologist like yourself among us. Your expertise will certainly help examining the martian terrain and features in threads like these with professional insight (even if that means that we might need to 'ground' some of our interpretations & theories).

By the way: do you happen to have an opinion on this thread by fellow ATS member Arken or other formations like those found in this OP (see mosaic on first page)? Are any of these especially intriguing to you?

Thanks again & I'm very much looking forward to seeing you around in this forum!

Many thanks for the warm welcome, I don't believe I'll be as much help you believe however as I'm rather hesitant to make a confident assessment of any geological feature based upon a few photographs. The Curiousity geology team have dozens of sedimentologists (I personally know one) and geologists on their panels and from what he says, more often than not their discussions end in deadlock because they hardly ever agree on anything. It's one of the main reasons why I think we need a manned mission ASAP, to get some boots on the ground and some proper field geology going. Curiousity is a fantastic piece of equipment but there's only so much a rover can do. But that's another argument.

As for your referenced material, I will admit that some of the outcrops do bear a resemblance to certain aspects of a vertebrae, however in the background of the main image there another outcrop of what appears to be the same rock type and that simply looks like a lump of rock. And because what we know of the Martian past, the existence of complex life at any point in the planet's history is thought to be rather slim. Like I say, if I was actually standing there myself I'd walk over and take a look, but if you're driving a £1 billion rover that trundles along at a few metres per hour, I can fully understand not wanting to delay the primary scientific goals of the mission to drive the rover over to a formation that looks slightly like a vertebrae (this is even assuming they spotted it).

Personally I think Mars almost certainly did have life and may continue to harbour it deep underground. I don't, however, believe that it was or is any more advanced than single celled organisms. I'd definitely say keep looking, but I think the smoking gun is yet to be found. And when it does come, it'll more than likely be microscopic. High hopes then for ExoMars in 2018.

reply to post by NoExpert


Complex past life on Mars might be difficult to imagine, especially when irrefutable signs for a complex eco-system on the surface are missing or not clearly shown up to this point. I wonder how massive meteorite impacts, volcanism, erosion, the loss of atmosphere over time and other events might have reshaped the surface to an extent that the majority of potential traces would be covered in dust or buried beneath the surface.

Whatever the case, I think it's good to have an extra opinion on all this from a geological point of view. So thanks again for responding to these threads & posts from time to time, and don't forget to let us know as soon as you've come across any images/features/formations that piqued 'your' interest ... would certainly be interesting to see which kind of rocks get geologists excited (although I understood that excitement is 'relative' if you can't grab that rock with your own hands and take a close look for yourself)!