Show us your stromatolites

[Yoda]

Green River Formation

Eocene

 

 

[Wrangellian]

Interesting... That one's quite different from the other Green River stuff I've seen.

[Wrangellian]

8 hours ago, MarcoSr said:

Edit:  Check out the below link on Gary Green Jasper.  This site has exceptional pictures and is run by a geologist with a bachelor’s and master’s degree in geology and who had a 40-year career as a geologist and geophysicist.

 

https://www.donwoolverton.com/gary-green-jasper

That may be the best summary of this material I've seen yet, as well as general info on jaspers.

[Yoda]

14 minutes ago, Wrangellian said:

Interesting... That one's quite different from the other Green River stuff I've seen.

I also have this one : 

 

 

[Wrangellian]

Ah yes. That one will look nice if you ever get it polished.

[MarcoSr]

5 hours ago, Yoda said:

Green River Formation

Eocene

 

 

 

3 hours ago, Wrangellian said:

Interesting... That one's quite different from the other Green River stuff I've seen.

 

Really nice piece.  Below is a somewhat similar piece that I have.

 

Hydrothermal Solution Middle Eocene Green River Formation Sweetwater Basin Wyoming (403grams 5.25x4.75x.375 inches)

 

 

 

 

 

 

 

Marco Sr.

[Wrangellian]

Maybe that one is from the same location as Yoda's?

[Yoda]

9 minutes ago, Wrangellian said:

Maybe that one is from the same location as Yoda's?

Both of mine came from that "friend of ours" on the bay 

 

No exact locality data.

Just : Green River Formation

[Yoda]

Remembered I had another Green River Stromatolite 

 

 

[Wrangellian]

Yes, I forgot to show my Green River specimen too...

Info according to the label:

Chlorellopsis sp, - Eocene, Green River Fm. - Wamsutter, Wyoming

 

Cut/polished surface:

 

Rough surface:

 

All the spaces between the digits appear to be filled with ooids(?):

 

 

13 hours ago, Yoda said:

Both of mine came from that "friend of ours" on the bay 

 

No exact locality data.

Just : Green River Formation

Yeah...

I'm thinking that you might be able to include the data from Marco's similar piece, as a possible location for yours.

Edited May 28, 2021 by Wrangellian
spacing

[MarcoSr]

13 hours ago, Yoda said:

Both of mine came from that "friend of ours" on the bay 

 

No exact locality data.

Just : Green River Formation

 

I see some nice pieces on the different websites but a lot of times the sellers have very little or no information on them because they came from an estate sale or a rock shop that closed years ago and had no tags or labels.  I actually don't like labels on my pieces or by them so I have a folder on my computer with pictures of each piece with the data in the file names.  Also I see pieces that were self collected by the sellers so you can get an accurate location for them but the sellers have no idea about the time periods or the formations etc.  At least with those pieces you can search the web for additional data.

 

Marco Sr.

[MarcoSr]

I really like pieces with oncolites.  Below is a small slab from hot springs in Peru.

 

Stromatolite oncolites,  thermophilic extreophilic microbes, from geothermal hot springs during the Pliocene to Pleistocene Age, from the high Andes Huanuco Region, Peru (96g 3.875x1.75x.31 inches)

 

 

 

 

 

 

 

 

 

 

 

Marco Sr.

[MarcoSr]

I recently acquired the below microbial mat slab ? (I believe it is) from the Pennsylvanian of Oklahoma.  Below is a short discussion from www.Ediacaran.org on how to identify a microbial mat and a NASA presentation on present day microbial mats.

 

Microbial mats are found fairly commonly on Ediacaran bedding planes worldwide, often alongside macro-fossils and trace fossils. Mats can be recognized as wrinkly surface textures on bedding planes (coming in a variety of forms commonly referred to as Microbially Induced Sedimentary Structures, or MISS), or more rarely as preserved assemblages of tiny pyritized filaments coating the surfaces of macrofossils (e.g. in the White Sea; Grazhdankin & Gerdes, 2007). Perhaps the most recognizable type of MISS is called 'elephant skin' texture, so-called for its cracked and wrinkled appearance. Microbial mats can also be recognized in thin sections cut through bedding planes, and can be identified by the characteristic way they orientate sediment grains (Noffke, 2009), or occasionally as microfossils of the original microbes (e.g. Callow & Brasier, 2009). However, many purely sedimentological (i.e. non-biological) processes can produce structures that look similar to MISS, and therefore it is often difficult to conclusively recognize true MISS in the field (Davies et al., 2016).  (from www.Ediacaran.org)

 

Nasa Presentation:

 

 

 

There is a very distinct pattern on this slab.  However, I can’t say for 100% sure whether it was created by microbes or just wind/water action. There are lots of inclusions in the slab (as can be seen in the pictures at high magnification below) but I can’t say for sure what they are.

 

Microbial mat slab?, Pennsylvanian 305 MYA, from the Hartshorne Sandstone from Haskell County, Oklahoma (1830grams 15.2x6.5x.6 inches).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Marco Sr.

[Wrangellian]

I would have ID'd that as wave ripples, but I can't say it was not colonized by slime (I believe I've seen ripples covered in algae/etc on the beach where the currents have changed/died down enough to allow it), I just can't tell from the rock we're looking at.

Is that piece coated in some sort of sealant? How did it get cut - is there a dealer selling this stuff by the square inch, or did it have to be cut to free it from the bedrock?

I like your photog style... The surrounding black makes the rock look good. How do you achieve that? Do you fill in the surrounding space using Photoshop or similar?

 

Speaking of stromatolite info, I found this in a link that Oxytropidoceras posted:

https://www.geological-digressions.com/the-art-of-the-stromatolite/

The original post (another page on that site) had to do with the formation of shungite, mostly found in Russia, about 2 billion years old. Apparently it's mostly organic carbon. I've been meaning to get myself a piece of that stuff.

Edited May 30, 2021 by Wrangellian

[MarcoSr]

2 hours ago, Wrangellian said:

I would have ID'd that as wave ripples, but I can't say it was not colonized by slime (I believe I've seen ripples covered in algae/etc on the beach where the currents have changed/died down enough to allow it), I just can't tell from the rock we're looking at.

Is that piece coated in some sort of sealant? How did it get cut - is there a dealer selling this stuff by the square inch, or did it have to be cut to free it from the bedrock?

I like your photog style... The surrounding black makes the rock look good. How do you achieve that? Do you fill in the surrounding space using Photoshop or similar?

 

Speaking of stromatolite info, I found this in a link that Oxytropidoceras posted:

https://www.geological-digressions.com/the-art-of-the-stromatolite/

The original post (another page on that site) had to do with the formation of shungite, mostly found in Russia, about 2 billion years old. Apparently it's mostly organic carbon. I've been meaning to get myself a piece of that stuff.

 

I looked at a number of papers on microbial mats.  All the picture examples pretty much looked like patterns caused by wind/water action to me.  I think you need to do thin sections, or recognize the microbes themselves in the pieces to be sure.  I even read that you can do a chemical analysis and look for chemical signatures.  A lot of the inclusions in this piece look like what I was seeing in the papers.  But to me the inclusions could be anything.

 

The piece isn't coated with any kind of sealer, natural color differences.  Most pieces of this that I saw on the web were the light grayish color of this piece on the right side.  The vast majority of this in Bing and Google images (probably at least 30 different pieces of different sizes) was from a major fossil dealer on the web that I bought from.  I think the piece had to be cut from the sandstone/sandstone block.  The thickness is too uniform, and I don't see sandstone uniform like this. Sandstone doesn't break along planes like shale or some other sedimentary rocks where you can find weathered out pieces like this.  I got a really good price for the piece itself that I just couldn't pass up.  Although when I saw the shipping cost, because of the size and weight, I almost backed out of the deal.

 

I take pictures of the slabs on a black background and then clean up the black in paint.net (freeware).  Depending on the lighting that I use to get the piece to look good, clean-up of the black can be very easy or take a bit of time.

 

Marco Sr.

 

 

[Wrangellian]

Ah, I thought it looked somewhat glossy/wet, but I guess as you say that's just the different colors of sediment in and between the ripples. I may also be misinterpreting the size. Well, not that much, 15" seems about right. Ripples are usually around the 1" range for size, I think? I believe the elephant skin stuff they talk about is smaller than wave ripples. Anyway not easy to confuse those two, once you've seen both.

I also think I see more widely-spaced waves in your piece - are those ridges running diagonally from upper left to lower right, against the ripples?

Are there saw marks on the back? Otherwise I would wonder how they got it down that thin unless it was a natural bed. I believe sandstone can come in thin beds too. That Coconino stuff with the animal tracks is sandstone, and it's thin-bedded.

[MarcoSr]

34 minutes ago, Wrangellian said:

Ah, I thought it looked somewhat glossy/wet, but I guess as you say that's just the different colors of sediment in and between the ripples. I may also be misinterpreting the size. Well, not that much, 15" seems about right. Ripples are usually around the 1" range for size, I think? I believe the elephant skin stuff they talk about is smaller than wave ripples. Anyway not easy to confuse those two, once you've seen both.

I also think I see more widely-spaced waves in your piece - are those ridges running diagonally from upper left to lower right, against the ripples?

Are there saw marks on the back? Otherwise I would wonder how they got it down that thin unless it was a natural bed. I believe sandstone can come in thin beds too. That Coconino stuff with the animal tracks is sandstone, and it's thin-bedded.

 

The elephant skin that I've seen doesn't have ripples.  See the picture below.

 

 

 

 

I see in the papers pictures of microbial mats that look like they are on top of ripples.  See the below picture (from www.Ediacaran.org).

 

An 'orange peel' sedimentary surface texture on the surface of a rippled bed, South Australia, preserving evidence for the original presence of a microbial mat.

 

 

 

 

If you look at the piece under magnification you can see a textured surface in a lot of areas.  You can see this texture in the below magnified pictures (two levels of magnification) from the piece.

 

 

The texture in most of this piece is similar to the "orange peel" texture but not as raised.

 

 

 

 

The texture in places on this piece is very similar to the elephant skin texture in the above picture.

 

 

 

 

The piece is a little longer than 15".  The back of the piece doesn't show obvious saw marks, but you can see a few short straight lines that seem to all run in the same direction and is fairly smooth but with some bumps and not polished.  If I had to guess, after looking closer at it, I would say that the back of the piece was chiseled and pried away from a different material. If you drew lines between the ripples, the lines would run in all directions (in some places almost circular) in the piece as you can see in the picture of the piece, so the ripples aren't oriented in one direction.

 

 

Marco Sr.

[Wrangellian]

Yes, those two examples at top are more what I picture when I think of elephant skin/microbial mat.

I'd like to see some oblique lighting on your piece to see the elephant skin - Your lighting seems to be diffuse or directly top-down (in your closeups) so it's hard to tell.

I don't think ripples are always straight and parallel... it would depend on the variability of the currents. But I could be wrong. One of these days I will go down to the beach to take pics of ripple marks at low tide. The sea is not too far from me, yet I haven't been there in ages! Other people who live far inland are probably jealous of people like me...

Edited May 31, 2021 by Wrangellian

[MarcoSr]

6 hours ago, Wrangellian said:

Yes, those two examples at top are more what I picture when I think of elephant skin/microbial mat.

I'd like to see some oblique lighting on your piece to see the elephant skin - Your lighting seems to be diffuse or directly top-down (in your closeups) so it's hard to tell.

I don't think ripples are always straight and parallel... it would depend on the variability of the currents. But I could be wrong. One of these days I will go down to the beach to take pics of ripple marks at low tide. The sea is not too far from me, yet I haven't been there in ages! Other people who live far inland are probably jealous of people like me...

 

I see ripple patterns all the time as I do most of my fossil collecting along running or tidal water.  I saw a lot of underwater ripple patterns diving.  However, I just didn't pay much attention to them.

 

I always try to take my pictures straight down, unless the piece is polished or chemically treated, which usually causes light hot spots from the camera flash or the microscope LEDs in the pictures.  To avoid light hotspots, I’ll take the camera flash pictures from an obtuse angle and angle the piece under my microscope.  I was able to take pictures of this piece straight down without light hotspots.

 

I’ll contact the sellers of the piece and inquire about what features of the piece led to the microbial ID and who made the determination.  I probably should have done that before I bought the piece, but it was on a very reputable website.  Right now, based upon what I see under the microscope and in the pictures, compared to what I see in on-line papers and websites, I have about a 60/40 confidence level that the piece is microbial.  Depending on the answer I get back, that confidence level could rise or fall.

Marco Sr.

[Wrangellian]

18 hours ago, MarcoSr said:

I always try to take my pictures straight down, unless the piece is polished or chemically treated, which usually causes light hot spots from the camera flash or the microscope LEDs in the pictures.  To avoid light hotspots, I’ll take the camera flash pictures from an obtuse angle and angle the piece under my microscope.  I was able to take pictures of this piece straight down without light hotspots.

I meant with the lighting at an angle. Camera can be straight down. In other words, can you replicate that 'orange peel' photo you showed above?

[MarcoSr]

The below piece exhibits a Kinneyia like wrinkle structure which is a prominent indicator of microbial mats formerly existing on the sedimentary surface:

 

 

 

 

See the paper Porada  Ghergut Bouougri 2008 Kinneyia-type wrinkle structures - Critical review and model of formation for a full discussion of this wrinkle srtructure.

 

The below figure from the paper shows examples of Kinneyia structures from various localities and ages:

 

 

 

 

A Kinneyia structure from Kinneyia  A hydrodynamic instability in the fossil record from www.lgoehring.com:

 

 

 

 

Kinneyia like structure in the Grimsby Formation, Silurian exposed in Niagara Gorge, New York from Microbial mat Wikipedia

 

 

 

 

Marco Sr.

[MarcoSr]

Here are pictures of another piece of supposed Bog Jasper that I just purchased that @Wrangellian showed in an above reply.

 

The piece itself:

 

Fossil Bog Jasper (a.k.a. Gary Green Larsonite) from the Trout Creek Formation, Miocene 11 to 14 Million Yrs. Old, McDermitt, Oregon (2 lbs. 9 oz. 3.5x4x4.75 inches)

 

 

 

 

 

 

Magnified close-up pictures of the cut face (rough not polished):

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Magnified close-up pictures of the rough uncut surfaces:

 

 

 

 

 

I don’t see evidence of petrified wood.  However, nothing jumps out to me as evidence of bog material, but I’m not sure what I should expect to see for bog material.

 

Marco Sr.

[Wrangellian]

13 hours ago, MarcoSr said:

The below piece exhibits a Kinneyia like wrinkle structure which is a prominent indicator of microbial mats formerly existing on the sedimentary surface:

 

See the paper Porada  Ghergut Bouougri 2008 Kinneyia-type wrinkle structures - Critical review and model of formation for a full discussion of this wrinkle srtructure.

 

The below figure from the paper shows examples of Kinneyia structures from various localities and ages:

 

A Kinneyia structure from Kinneyia  A hydrodynamic instability in the fossil record from www.lgoehring.com:

 

Kinneyia like structure in the Grimsby Formation, Silurian exposed in Niagara Gorge, New York from Microbial mat Wikipedia

Could be..... Are the scales comparable?

 

4 hours ago, MarcoSr said:

Here are pictures of another piece of supposed Bog Jasper that I just purchased that @Wrangellian showed in an above reply.

The piece itself:

....

I don’t see evidence of petrified wood.  However, nothing jumps out to me as evidence of bog material, but I’m not sure what I should expect to see for bog material.

I like that piece. Should look nice (esp. magnified images) once it's polished.

By the description of the deposit it sounds like you could have any number of things there, maybe microbialites are one of them. I don't know what else this piece could be.. or maybe it's not actually from McDermitt??

[nala]

Few samples,Stromatolite – Acaciella australica Howchin, 1914. Precambrian, Bitter Springs Group. Gillen Member Fitzroy Crossing, Ross River District. Northern Territory Australia

Stromatolite. Conophytum basalticum Walter, 1972. Precambrian, Antrim Basalt formation.Top Spring near 'Wave Hill' Pastoral Station. Northern Territory Australia

Stromatolite. Late Pleistocene. Marion Lake, Stenhouse Bay area. South Australia.

Stromatolite from Assas (around Montpellier) dating from 300 million years ago France

Stromatolites of the Upper Precambrian in the Adrar of Mauritania (western. Sahara).

 

 

Edited June 4, 2021 by nala

[MarcoSr]

4 hours ago, Wrangellian said:

Could be..... Are the scales comparable?

 

Yes and the wrinkles have more or less regular troughs and crests with amplitudes in the range of 0.3–3 mm with intercrest distances of 1–5 mm which match the descriptions in the paper.  I'm pretty certain now, after reading the paper and looking at pictures, that the slab shows evidence of a microbial mat.

 

4 hours ago, Wrangellian said:

I like that piece. Should look nice (esp. magnified images) once it's polished.

By the description of the deposit it sounds like you could have any number of things there, maybe microbialites are one of them. I don't know what else this piece could be.. or maybe it's not actually from McDermitt??

 

Where pieces come from is always a question, especially when the sellers don't collect the piece themselves.  The piece should look nice polished.  I can hand polish the cut face, but I may want to get the rest of the rough surface lightly polished (not freeform as I still want texture) to show detail there also.

 

Marco Sr.