Are concretions formed by microorganisms?

Definition of a stromatolite:

"stro·mat·o·lite ( P ) Pronunciation Key (str-mtl-t)
n.

A widely distributed sedimentary structure consisting of laminated carbonate or silicate rocks, produced over geologic time by the trapping, binding, or precipitating of sediment by groups of microorganisms, primarily cyanobacteria."

The question that I have then, is "Are concretions stromatolites or stromatolite-like objects?"

Courtesy of RPage:

/R

marsman

If they were, I'd be happy.

Not every laminated rock is a stromatolite, even if it fills the letter of the definition. The term is generally used only in connection for those features that are almost certainly microbial in origin. However some features called stromatolites are now thought to be abiogenic preciptations, and are no longer called stromatolites.

However stromatolites are never spheroidal. Stromatolites are either domal or columnar. Although originally applied to flat-laminated sediments, the term is rarely applied to such sediments today. Spheroidal microbialites are called oncoids.

Additionally stromatolites form on the sediment water interface. They do not form at depth either though diagenesis or weathering.

To add to the confusion, not all stromatolites are laminated. These are called thrombolites because of their clotted fabric.

The martian features show little evidence of internal lamination. There is no evidence for microbial activity. They are spherical, not domal or columnal. The martian features clearly formed beneath the surface through diagenesis or weathering. So they not stromatolitic in in any sense of the word.

What is the provenance of those great pictures by the way? Where are they form, what litwerature do you have on them?

Cheers

Jon

These pictures were sent via email from RPage. Here is another one that shows the concentric layering of an Ordovician Spherule:

Maybe these are oncoids.

[Link]

/R

marsman

This is a picture from Mars (with an inlaid lower corner comparison picture from Earth) (Courtesy of Mann):

The spherical shaped objects in the Mars portion of this picture appear to be domal, IMO.

Mann,

Do you remember what Sol this picture came from?

/R

marsman

Marsman, thanks for posting these images. I have many more images that I would like to put up for discussion here.

In regard to Reply #3:

That is not an image from the Wisconsin Ordovician Glenwood Formation. I found that in a nearby cornfield in northern Illinois and do not know what age it is. It is likely Silurian, Ordovician or older. I would guess that it is an Ordovician or Silurian sponge-like organism but I do not know for sure. I’m sure that someone out there can identify it.

Jon, in regard to Reply #2:

Stromatolites form colonies that are composed primarily of cyanobacteria. It is likely that many stromatolites represent colonies of bacteria with cyanobacteria constituting the majority but with other microorganisms present. In a symbotic association of microorganisms greater adaptation to adverse conditions could be possible. Some of the Ordovician spherules/structures may have formed on or near the surface and others may have formed under water or underground (post deposition). The Ord. Spherules and the Moqui Marbles may have contained cyanobacteria and may have formed underground. I assembled a summary comparing the Earth stromatolites, the Ordovician spherules, and the Mars berries back in April of 2004. Horton helped in reducing image size and hosting the link:

http://www.lipfordm.com/wtsi/RPage/RPage.htm

A few months after that, I found Ulrike Brehm’s studies and it just about blew my socks right off:

http://paleopolis.rediris.es/cg/CG2004_L03/

Ulrike has been studying living spherical communities of bacteria/microorganisms (cyanobacteria, heterotrophic bacteria and benthic diatoms) that work together in an apparent symbiotic relationship to build larger spherical structures. During my correspondence with Ulrike he agreed to examine the Ordovician spherules. I have asked Marsman to post the SEM images that Ulrike has recently produced of the Ord. Spherules. These Sem images exhibit what appear to be fossilized bacteria in thin carbon films throughout the spherules. I would guess that further investigation will reveal a inner multiple concentric layering of thin carbon films within the spherules and the carbon layers will reveal bacterial structures.

While this is hardly conclusive proof of life on Mars, I think that it is a BIG deal.
We are proving that many concretions may be a result of microorganism interaction. The Ordovician spherules, Moqui marbles and some other Earth concretions are morphologically similar to the Mars berries. While we may have to wait 20 or more years for a Mars sample return mission we have this topic to explore. This is a very exciting time in planetary exploration!!

I would appreciate any interpretation on the following SEM images or the Ordovician spherules. Are these biological or non-biological?

Robert Page

The Ord. Spherules and the Moqui Marbles may have contained cyanobacteria and/or other microorganisms and likely formed underground. The main theme here is that these appear to be biological structures, they could be bacterial or fungal, or even nanobe and/or could constitute a symbiotic community. Information so far seems to indicate that they contain a bacterial variety, extremophilic or otherwise.

Thats a cool link to Brehm's studies.
I read through his paper, retaining what i could. This is what led me to looking at images of colonial bacterias, actually, colonial organisms, of all types.

Marsman, this is sol 25.

The earth crop is a colonial bacteria, found in the dirt. Amazing, every time i see this comparision, very simular.

I believe a symbiotic relationship, or a growth, of colonial organism, maybe death, or takeover of a different microbial organism, resulting in hematite replacement.

That probably dosn't make any sense, but i'm just a guy off the street.

"There is no evidence" for microbial activity?
I'm curious what type of evidence you would except Jon Clarke?

I can visualize what we would see with a higher magnification.

Can anyone, not see, the products, of biological activity, in this image?

Can you see the tiny berry in crown ring?

Can you see the starfish shape on the bottom berry in reply 4, 12 oclock?

Can you see the tiny berry in crowned ring, that sits On Top, of the berry, in my image here?

Dana johnson was the first to point out the starfish shapes on the berries. i think these are related to the crowned rings, with berries.

In my sol 106 thread, i will post what i see in this image.

Bingo!

Don't forget this crowned ring ripped from it's base:

Lot's of stuff here to comment on, so i will take them in order.

Reply 3:

That sort of open semi-concentric structure is reminiscent on what you might find in an oncoid. What a geologist would do is take a thin section of that to look for further evidence. If you can tell me where these spheroids are from and what formation they comprise I might be able to find some literature. Simply stating they are "Ordovician" is not enough. The Ordovician lasted close on 50 My and Ordovician rocks are found on every continent, deposited in environments randing from deep marine to subaerial and even subglacial.

Reply 4: There is not enough information in that image to say whether the rounded shapes are domal or not. We need to know the orientation of the image with respect to bedding. Are we looking at a cross section through bedding, down on a bedding plain, up at the bottom, what? Are the rounded features in situ or in a secondary deposit? What is the larger context of the setting? the same applies to the terrestrial examples. You need much more information before you can start drawing conclusions.

Reply 5:

Thanks for the information on the Ordovician examples. There may be a literature on these things, I will try to find out. I doubt they are sponges though, sponges have very distinctive external and internal morphology and these look nothing like them.

Brehm’s work is interesting but it would be much more impressive if it were done from an environment that actually formed ooids (like the Persian Gulf, Bahama Banks, or Shark Bay), rather than one that is about as far removed from an ooid forming envirnment that you can get and still be marine, namely the North Sea. It would also do much for the credibility of the work if he had recognised that there is no genetic link between diatoms and ooids.

Reply 6:

The Mocqui Marbles form during deep burial diagenesis. Cyanobacteria are photosynthetic organisms. There is no way that cynaobacteria could have played a role - it's dark down there. If microoorganisms did play a role (pure conjecture at this stage) they would have to have been iron oxidising bactera, very different organisms
indeed.

As for the supposed Ordovician examples it is vital to known when they formed in the history of the rock. Are they depositional, did they form during deep burial, or are they the result of weathering? Until we know there context we can't begin to understand their origin, whether or not they may be microbial, let alone speculate as to their relevance as possible analogues for Martian features.

Reply 7:

What is the context of the MI?

What is the context of the terrestrial example? What is the scale of the image? What aspect of the image is microbial and how do you know? What is the nature of the shiny rounded objects and the white material?

Reply 8:

I see nothing remotely biological in that image. If you had seen as many non-biological rounded grains (ooids, pisoids, peloids, nodules, concretions, vadoids etc.) as I have you wouldn't jump to a biological explanation either.

Cheers

Jon

PS: This discussion could rapidly blow out of hand. How about we start by addressing the title question with respect to the "Ordovician" examples? To do this we need to know:

1) What unit they are from and what literature exists about it

2) What is their age

3) What is their composition and what literature exists about them

4) What is their morphology and what features are they associated with

5) What is their internal structure down to the microscopic scale

5) When did they form in the history of the rock (deposition, burial, weathering)

If we do this I think we will have a much better understanding about these features and people will also have a better understanding on how to determine biological and non-biological origins in terrestrial rocks and the issues involved with doing the same on Mars.

This is a picture of a well-preserved spherule that shows concentric layering. In fact, it shows three distinct layers. With reference to the nearby adjacent spherules, the one towards the upper left shows a smaller spherule starting to project out of the larger spherule. The one on the lower right shows a spherule that has a seam going down the middle.

[Link]

/R

marsman

Here is an interesting article to read:

"Electron and light microscopy showed that oncoids possess distinctly zoned microbial communities consisting of a surficial assemblage of larger (>10-micron diameter) filamentous cyanobacteria and diatoms, overlying a subsurface community (1-2 mm depth) that is dominated by finely filamentous and coccoidal (

[Link]

/R

marsman

John, I think Marsmann and mann are discussing pachytheca, see

this thread

Re 4 shows an image of pachytheca side by side with a martian spherule, and you must admit the similarity is shocking.

Here is another image of pachytheca

Adn RPage discusses the ordovican spherules in detail in his article

here

I agree I do not see anything in Mann's post 8. I know mann sees something there, but I do not get it. I think the analogy to
pachytheca is much more exciting.

Here is an excellent resource for pacytheca, where I got my image reference from.

marsman, I had examined this item many times and not sure it was a spherule now. Beside its geometry is different from spherules, its surface is too smooth or featureless for a berry, compare it with the upper berry on that image.

Re reply 12:

That is one of the few clear examples of concentric layering of a Mars concretion. A few otehrs appear to have a single outer layer. Most of the ratted or fractured ones don't.

Re reply 13:

This link is a study of oncoids, by definition the results of microbial activity. Of itself this says nothing about the origin of Martian concretions.

Re reply 14:

Any small round object resembles Pachytheca. The Martian concretions have a completely different composition and, more importantly, utterly different internal structure. The Martian concretions have no real resemble to Pachytheca.

Why don't we focus on the Ordovocian examples, as I suggested. I will look up the Glenwood formation and see what I can find.

Cheers

Jon

I think a very good point was made that concretions can be formed by different types of bacteria (other than cyanobacteria). For instance, Ferromanganese concretions from the Baltic Sea:

[Link]

/R

marsman

"Concretions "Kettles" (Sedimentary rock), Kettle Point. Paleozoic Upper Devonian 370 million years ago Kettle Point Formation. The concretions are known as Kettles and are found in shale along the shore of Lake Huron at Kettle Point. The Kettles were formed while the mud which formed them was still soft. Bacteria in the mud caused sulphate reduction and the precipitation of concretions. The crystals formed in a radiating pattern, from the centre out, creating a ball these can range in size from 30cms to 1.5 metres across. The pieces in the geological garden are fragments from a ball."

[Link]

/R

marsman

"That is one of the few clear examples of concentric layering of a Mars concretion. A few otehrs appear to have a single outer layer. Most of the ratted or fractured ones don't. "

True, however this statement by itself does not deny the existence of concentric layering of the Mars Spherules. We have a picture of a well-preserved specimen that shows concentric layering (Reply 12). Maybe the other (less clear) specimens are not as well preserved or were preserved differently. Maybe they were formed differently. The only problem with this particular hypothesis "formed differently" is that the size distribution profile for these spherules is roughly the same regardless of location. Thus, the problem remains. Some spherules show clear concentric layering while others do not, and yet they still belong to the same population.

The RAT is a rock grinding tool. How are we going to see clear detail from something that was bludgeoned with clockwise grindings and scrapings from a RAT?

Back to the concretions formed by microrganisms question:

"The pyrite concretions might indicate that the bay muds contained sulfur reducing bacteria, which fed on the abundant organic material in the bottom muds. The production of abundant H2S in the sediments surrounding the delta could explain the low PH phenomenon."

[Link]

/R

marsman