Petrified wood with bore holes and small fossils

[Steve Gass]

I found this really interesting rock while cleaning my pond over the weekend. The pond is lined with round river rocks (presumably mined here in Oregon) and this one caught my eye as I was cleaning. When I looked at it a little closer, it appears to be petrified wood with some type of bore holes. Some of the bore holes are filled with what looks like agate and others have what one might imagine a dried out petrified worm might look like. I looked at it under magnification and noticed what looks like a couple of very small (<1/8") fossils. The clearest one is in the center of the first photo. One half looks like a series of radial lines (like a pill bug) and the adjacent half looks like really tiny scales or similar regular texture which isn't really visible in the photo and I couldn't get a shot through the scope. Is this actually petrified wood with bore holes and how does the agate-like material get in there and could a worm or grub get petrified?

 

Thanks for your thoughts.

 

Steve

[Oxytropidoceras]

Teredolites - "Teredolites is an ichnogenus of trace fossil, characterized by borings in substrates such as wood or amber."

 

Gingras, M.K., Maceachern, J.A. and Pickerill, R.K., 2004. Modern perspectives on the Teredolites ichnofacies: observations from Willapa Bay, Washington. Palaios, 19(1), pp.79-88.

 

I would interpret the sequence of events as the wood being first bored by bivalves, buried, and finally silicified. The worm-like features are the sides of borings in wood with their texture reflecting episodic nature of how the bivalves bored the wood.

 

Yours,

 

Paul H.

Edited February 17, 2022 by Oxytropidoceras
added paper

[Mahnmut]

4 minutes ago, Oxytropidoceras said:

Teredolites - "Teredolites is an ichnogenus of trace fossil, characterized by borings in substrates such as wood or amber."

 

 

Just because I do not completely understand the concept:

Possibly different kinds of borings are subsumed under the ichnogenus Teredolites, but with preserved parts of the animal still in place it would be at least theoretically possible to determine a "normal" (organism vs trace) genus?

Best Regards,

J

[Thomas.Dodson]

20 minutes ago, Mahnmut said:

Just because I do not completely understand the concept:

Possibly different kinds of borings are subsumed under the ichnogenus Teredolites, but with preserved parts of the animal still in place it would be at least theoretically possible to determine a "normal" (organism vs trace) genus?

Best Regards,

J

Teredo and the Teredo-like genera have had species erected in the past based on the "actual" organism. In fact, picture #1 shows a Teredo-type bivalve in the boring. However, Teredolites is a ichnogenus alone; it only applies to the trace fossil. For example, the bivalve is distinct, perhaps Teredo sp., but the burrows themselves are only ever Teredolites.

 

Specimens 4. and 5. below are different Teredo species.

[abyssunder]

Teredolites, a very nice example! 

(using the xylic substrate as ichnotaxobase)

Edited February 17, 2022 by abyssunder

[abyssunder]

1 hour ago, Mahnmut said:

Just because I do not completely understand the concept:

Possibly different kinds of borings are subsumed under the ichnogenus Teredolites, but with preserved parts of the animal still in place it would be at least theoretically possible to determine a "normal" (organism vs trace) genus?

Best Regards,

J

bivalves

[Steve Gass]

1 hour ago, Oxytropidoceras said:

I would interpret the sequence of events as the wood being first bored by bivalves, buried, and finally silicified. The worm-like features are the sides of borings in wood with their texture reflecting episodic nature of how the bivalves bored the wood.

Am I correct in interpreting your comment to imply that it is normal for the wood to petrify as a first step with bores remaining open and then later being filled with the agate (silicified - new word for the day)? Intuitively, I'd think it would be odd for the bores to remain open while the original petrification took place. 

 

Also, I guess the definition of teredolites includes both the positive and negative images for the bores - i.e. both bore voids in a separate medium and the fossilized 'clubs' that presumably formed in the filling of such voids? 

 

I appreciate the well-informed answers from all - thank you!

[Oxytropidoceras]

4 hours ago, Steve Gass said:

Am I correct in interpreting your comment to imply that it is normal for the wood to petrify as a first step with bores remaining open and then later being filled with the agate (silicified - new word for the day)? Intuitively, I'd think it would be odd for the bores to remain open while the original petrification took place. 

 

Also, I guess the definition of teredolites includes both the positive and negative images for the bores - i.e. both bore voids in a separate medium and the fossilized 'clubs' that presumably formed in the filling of such voids? 

 

I appreciate the well-informed answers from all - thank you!

 

In more detail, I meant to say, first wood, would get washed into the sea. Second, it become waterlogged and sink to the bottom. Third, while lying exposed on the bottom, small pelecypods will bore into the wood and riddle it with holes. Fourth, after being bored and riddled with holes, a sudden influx of sediment would bury the wood and fill the hole with sediment. Fifth, while the sediment is still mud and before it compacted and lithified, excess silica in the pore waters will attached itself preferentially to and eventually replace the organic matter conprising the wood as it decayed with agate. The mud, lacking oganic matter, will remain unaffected by the excess silica. Six, after the wood is silicified, it would buried deep enough to be changed to either shale or mudstone. Finally, after the strata containing the silicified teredolite has been tectonically uplifed and exposed by erosion, the excasing strata will be eroded and exposing the silicified teredolite. The shale / mudstone will be preferentially removed from around the harder pieces of silicified teredolite by weathering and from inside the borings leaving behind empty borings as voids.

 

If the wood is not silicified, it will be coalified and compressed around mud-filled borings that will become mudstone-filled borings. In this case, the mudstone-filled borings are more resistent to weathering then the coalified wood. The coalified wood will be destroyed by oxidation of exposed strata and the lithified mudstone-filled borings as the 'clubs' mentioned above.

 

The impression that I get is that "...teredolites includes both the positive and negative images for the bores..."

 

General papers on the fossilization and preservation of wood.

 

Mustoe, G.E., 2017. Wood petrifaction: A new view of permineralization and replacement. Geosciences, 7(4), p.119.

 

Open access version of above paper.

 

Mustoe, G.E., 2018. Non-mineralized fossil wood. Geosciences, 8(6), p.223.

 

Researchgate Version of above paper

 

More papers about silicified wood on Researchgate

 

Yours,

 

Paul H.

 

 

Edited February 18, 2022 by Oxytropidoceras
fine-tuned sentence wording

[Steve Gass]

Thank you Paul H. for the very helpful elaboration. It sounds like this particular specimen must have had quite the journey to get to it's present state, with both positive and negative teredolites, petrified substrate and fossil remains of the bivalves that likely created the bores. 

 

Take care,

 

Steve