Please help identify

[abyssunder]

Good work, Hank and my appreciation for Steve Kershaw for his interest and determination, and last but not least, I'm glad I wasn't wrong in my initial thinking.

[GeschWhat]

What an interesting, informative thread! @Hank, thank you for posting all the wonderful photos, having your sample cut and sharing informational you received from Steve K. 

[Hank]

One additional note to this topic, I received the following email from Dr Kershaw regarding an educated guess that the specimen could have come from the Mississippian or Devonian period:

Dear Hank,

 

I am pleased it was helpful. It is interesting to learn that you may have Mississippian stromatoporoids, because these are not at all common, only a few specimens have been reported before. I suspect it is more likely to be Devonian, but if a Mississippian age is confirmed then that is most interesting. The stromatoporoids became pretty much extinct at the end of the Devonian.

 

Do let me know if you discover anything more, and if I can be of any more help, do please keep contact.

 

 

Best wishes

Steve

 

I am not adept at understanding how geologic formations move with time.  This piece came from an area where it could have been deposited from erosion of the grand canyon, probably from devonian age material.  If anyone has a better idea of how to place this in the proper period I would love to hear your opinion.  From what Dr Kershaw said, it would be rare to find a stromatoporiod  from the Mississippian age.

[ynot]

4 minutes ago, Hank said:

If anyone has a better idea of how to place this in the proper period I would love to hear your opinion. 

The piece is not showing river erosion.  I think it has not traveled far from it's formation.

The only way to be sure of the age is to trace it back to the formation and find some in situ pieces.

[Hank]

Alright, I will see what I have from the same place and if possible will go back when it cools down a bit.

[DPS Ammonite]

49 minutes ago, Hank said:

Alright, I will see what I have from the same place and if possible will go back when it cools down a bit.

Take a look at a geological map of Arizona (link below). What rock unit did the rock come from? I am curious to see if the area is Colorado River gravels deposited in the last 6 million years. Also take pictures of some of the other associated rocks. That might help to determine if this is river gravel or gravel/alluvium from a closer source.

 

http://www.azgs.az.gov/services_azgeomap.shtml

 

See photo of partially silicified probable stromatolite from the Redwall Limestone from Gila County, Arizona. I say probable because I see no pillars in any laminated layer. Note how the layers continue from the gray limestone into the white/ brown chert. Yours may come from the same formation.

 

 

 

[DPS Ammonite]

Here is a photo of the other side of the probable stromatolite from Gila County, AZ:

[Hank]

Here is the area I found the specimen.  The blue dot shows the location.  The legend displayed corresponds to the area.

[DPS Ammonite]

7 hours ago, Hank said:

Here is the area I found the specimen.  The blue dot shows the location.  The legend displayed corresponds to the area.

There are no local sources for the likely Paleozoic fossil. You found it in an area that has some terrace (Colorado River) deposits. Nearby Miocene gravel/alluvium deposits could also be a source that has been reworked. The nearest sources of suitable Paleozoic rocks are on eastern Lake Mead near Pierce's Ferry (the Grand Canyon is the most likely source).

 

Keep an eye out for relatively recent petrified wood that was formed in the ancient bed of the Colorado River and occurs from below Lake Mead to Yuma.

 

[cyruspup]

Hello Hank

 

I have found over 20 stromatolites  in Golden Shores and this rock you picture is weathered sandstone type rock. I have found many that look like this. Pictures below is Golden Shores Stromatolite.