Stromatoporoid

[Peat Burns]

I think this is a stromatoporoid but would like additional opinions before I label it.  It comes from dolomitized middle Silurian limestone of northern Michigan.  I thought it might be coral that had undergone diagenesis, but there are well-preserved Favosites present, so I'm pretty sure it's Stromatoporoid.  They were abundant, as were the corals.

 

Here's one in the matrix:

 

Here's my specimen (cut with saw):

 

Here's a "thin" section and an acetate peel:

[Peat Burns]

And here's a magnified view:

[doushantuo]

I wouldn't say "unmistakable stromatoporoid",but it looks like one.Pillars might be more altered than latilaminae due to diagenesis.

[Rockwood]

Is there any chance of it being red algae ? I've read about it being a reef building component but never seen it identified. 

[Johannes]

Some types of red algae start to be reef relevant organisms in the early Mesozoic (Bernecker 2005), but their real importance was since Eocene times (Lipps & Stanley 2016).....

[FranzBernhard]

If I would find such a thing in the Devonian of Graz, Styria, Austria, it would be identified as stromatoporid by the local experts.

Polished slabs of Favosites growing on toppled stromatoporid.

[Tidgy's Dad]

It looks like a classic stromatoporoid to me, layering, dome shaped mass, pillars in cross-section. 

Nice find, Tony! 

[Peat Burns]

8 hours ago, Rockwood said:

Is there any chance of it being red algae ? I've read about it being a reef building component but never seen it identified. 

Good thought. I have some Ordovician calcareous red algae (see below). This one differs in that, although it has fine laminae, it lacks any pore structure like the proposed stromatoporoid.

[Peat Burns]

Thanks @Rockwood, @doushantuo, @FranzBernhard, @Johannes, and @Tidgy's Dad 

 

I will label this as stromatoporoid 

[Tidgy's Dad]

3 minutes ago, Peat Burns said:

Good thought. I have some Ordovician calcareous red algae (see below). This one differs in that, although it has fine laminae, it lacks any pore structure like the proposed stromatoporoid.

 

That's very nice! 

[Johannes]

2 hours ago, Peat Burns said:

Good thought. I have some Ordovician calcareous red algae (see below). This one differs in that, although it has fine laminae, it lacks any pore structure like the proposed stromatoporoid.

 

 

Hmm. From ordovician deposits I know only rare coraline red algae. But there are some other types of calcareous algae, and some stromatoporid crusts with less obvious pore structures. Are you sure with the ID "red algae" for the last one?

[Bobby Rico]

2 hours ago, Peat Burns said:

Good thought. I have some Ordovician calcareous red algae (see below). This one differs in that, although it has fine laminae, it lacks any pore structure like the proposed stromatoporoid.

That is a really beautiful specimen. 

[Peat Burns]

22 minutes ago, Johannes said:

 

Hmm. From ordovician deposits I know only rare coraline red algae. But there are some other types of calcareous algae, and some stromatoporid crusts with less obvious pore structures. Are you sure with the ID "red algae" for the last one?

Yes, it is "Solenopora" (name now invalid because the name Solenopora was given to the holotype of a Eurpean chaetetid sponge that was previously thought to be algae). The red alga shown above is waiting a new name. The orange color comes from boron, presumably a fossil element rather than a replacement element).

[Peat Burns]

20 minutes ago, Bobby Rico said:

That is a really beautiful specimen. 

Thanks, Bobby 

[Johannes]

8 minutes ago, Peat Burns said:

Yes, it is "Solenopora" (name now invalid because the name Solenopora was given to the holotype of a Eurpean chaetetid sponge that was previously thought to be algae). The red alga shown above is waiting a new name. The orange color comes from boron, presumably a fossil element rather than a replacement element).

Ah, ok, I wasn't aware that the solenopora-problem for the palaeozoic ones is solved now. And nice that you have prooven the the boron pigments for the Ordovician, I only know the work of Wolkenstein et al. 2010 for the Jurassic red algae... Hoping to read about that soon.

 

Best regards

 

Johannes

[Peat Burns]

5 hours ago, Johannes said:

Ah, ok, I wasn't aware that the solenopora-problem for the palaeozoic ones is solved now. And nice that you have prooven the the boron pigments for the Ordovician, I only know the work of Wolkenstein et al. 2010 for the Jurassic red algae... Hoping to read about that soon.

 

Best regards

 

Johannes

@Johannes I thought you might like to see a whole algal thallus.  Here are a couple pics.

[Peat Burns]

[abyssunder]

12 hours ago, Tidgy's Dad said:

It looks like a classic stromatoporoid to me, layering, dome shaped mass, pillars in cross-section.

I agree.

[FranzBernhard]

4 hours ago, Peat Burns said:

 I thought you might like to see a whole algal thallus.  Here are a couple pics.

Thanks for the pics! Sure this does not look like a classical stromatoporid! Very informative!

 

10 hours ago, Peat Burns said:

Yes, it is "Solenopora" (name now invalid because the name Solenopora was given to the holotype of a Eurpean chaetetid sponge that was previously thought to be algae). The red alga shown above is waiting a new name. The orange color comes from boron, presumably a fossil element rather than a replacement element).

Is this your own research work and/or are there some papers/abstracts out there? Very interesting topic!!

Franz Bernhard

[Peat Burns]

56 minutes ago, FranzBernhard said:

Thanks for the pics! Sure this does not look like a classical stromatoporid! Very informative!

 

Is this your own research work and/or are there some papers/abstracts out there? Very interesting topic!!

Franz Bernhard

No, this is not based on my research  but what seems to be accepted (re their classification as calcareous red algae). I'm not sure if the boron has been confirmed and published for the late-Ordovician specimens.  This was related to me by a colleague, so I'll have to check the original source. If it hasn't been formally confirmed, I will pursue an investigation on it myself.

 

I am away from my library for the remainder of the weekend, but here are some papers that may be of interest:

 

Xiao, S., A. H. Knoll, X. Yuan & C. M. Pueschel. 2004. Phosphatized Multicellular Algae in the Neoproterozoic Doushantuo Formation, China, and the Early Evolution of Florideophyte Red Algae.  American Journal of Botany 91:  214-227.  (See p. 225, bottom of left column)

Blackwell, W. H., J. H
Marak, & M. J. Powell (1982). The Identity and Reproductive Structures of a misplaced Solenopora (Rhodophycophyta) from the Ordovician of Southwestern Ohio and Eastern Indiana. Journal of Phycology. 18: 477 - 482.

Wolkenstein, K., J.H. Gross, J. & H. Falk. 2010.  Boron-containing organic pigments from a Jurassic red alga.  Proceedings of the National Academy of Sciences. 107: 19374 - 19378

[FranzBernhard]

2 hours ago, Peat Burns said:

No, this is not based on my research  but what seems to be accepted (re their classification as calcareous red algae). I'm not sure if the boron has been confirmed and published for the late-Ordovician specimens.  This was related to me by a colleague, so I'll have to check the original source. If it hasn't been formally confirmed, I will pursue an investigation on it myself.

 

Thank you very much for the infos and the papers!

Franz Bernhard

[Johannes]

17 hours ago, Peat Burns said:

@Johannes I thought you might like to see a whole algal thallus.  Here are a couple pics.

 

Thank you very much!