Fossil found in Douro river area (near Porto, Portugal)

[Eduardo]

I found this fossil near Porto, Portgal.

The geological area is known as Xisto-Grauvaquico Complex (Middle Cambrian).

[Plantguy]

Neat find. I gonna take a guess and think its possibly younger than Cambrian which had no terrestrial plants. Maybe some Carboniferous aged finds maybe older? that have been eroded as part of that geologic area/basin??...

 

Take a look at this reference below-- figure 6. maybe it could be one of the sphenopsids..like Annularia/asterophyllites or others..

 

A new Late Pennsylvanian floral assemblage from the Douro
Basin, Portugal

 

https://www.researchgate.net/profile/Pedro-Correia-11/publication/320433771_A_new_Late_Pennsylvanian_floral_assemblage_from_the_Douro_Basin_Portugal/links/5ada3c490f7e9b28593e5914/A-new-Late-Pennsylvanian-floral-assemblage-from-the-Douro-Basin-Portugal.pdf

 

Pedro Correia one of the coauthors looks like one of the most recent investigators...Geosciences Center · Earth Sciences Department of University of Coimbra, PhD

He could possibly confirm what you have unless someone here on the forum can

add something further...Let us know if you reach out to him...

 

 

Continued hunting success!

Regards, Chris 

[Eduardo]

Thank you very much, Chris!

Yesterday I sent an email to Pedro Correia, and I am waiting for the reply. 

 

Thanks for the quick reply.

Best regards, Eduardo

[FranzBernhard]

Aren´t these some (contact-)metamorphic minerals (amphibole? tourmaline?) growing in a schist?
Franz Bernhard

[Eduardo]

Hi Franz, thank you very much for the reply.

I will post more photos later, maybe it will be more clear.

 

Best regards, Eduardo

[Plantguy]

3 hours ago, FranzBernhard said:

Aren´t these some (contact-)metamorphic minerals (amphibole? tourmaline?) growing in a schist?
Franz Bernhard

I agree Franz it looks suspicious and it might be purely mineralogic... sometimes I just want to hold some of these things in my hand with a loop/lens!

 

Regards Chris 

[DPS Ammonite]

On 7/3/2024 at 6:09 AM, Eduardo said:

Xisto-Grauvaquico Complex (Middle Cambrian).

 

Xisto-Grauvaquico translates as “schist-greywacke” both metamorphic rocks. Franz is right about it being metamorphic.

 

Fossils are unlikely.

 

If you research this rock group, you will find that it is metamorphic. A mica rich schist or phyllite is likely.

 

https://repositorio.lneg.pt/bitstream/10400.9/2616/1/30538.pdf

 

https://www.rupestre.net/tracce/?p=1047

 

 

 

Edited Thursday at 01:46 PM by DPS Ammonite

[Mahnmut]

4 hours ago, DPS Ammonite said:

 

Xisto-Grauvaquico translates as “schist-greywacke” both metamorphic rocks.

 

Hi, I agree Schist- Greywacke appears to be metamorphic, but greywacke in itself isnt.

https://en.wikipedia.org/wiki/Greywacke

I spent most of my youth on greywacke, which had abundant fossils.

So I think Xisto-Grauvaquico describes a Schist that resulted from metamorphosis of Grauwacke?

Best regards,

J

[DPS Ammonite]

9 minutes ago, Mahnmut said:

Hi, I agree Schist- Greywacke appears to be metamorphic, but greywacke in itself isnt.

https://en.wikipedia.org/wiki/Greywacke

I spent most of my youth on greywacke, which had abundant fossils.

So I think Xisto-Grauvaquico describes a Schist that resulted from metamorphosis of Grauwacke?

Best regards,

J

Greywacke is not necessarily metamorphic and could contain fossils. You are right. Thank you. I have not  read the details in Portuguese to see if the greywacke has metamorphic minerals in it. In the San Francisco Bay area a lot of the Franciscan greywacke is metamorphosed to the green schist faces, but still contains rare fossils.