This feature occurs in Katian / Hirnantian transition strata in West Wales - in laminated hemi-pelagite. It is about 200mm high and 100mm across. There are a number of similar features in the strata 25m or so below this one (it occurs at least 8 times with varying details of morphology. Much of the rock below this level is full of Chondrites style burrows. Looks to me like some form of infilled Dominichnial shaft between surface and deep burrows...any further thoughts?
Is this really a trace fossil? For me it looks more like a (syn?)sedimentary structure. Can you water the surface and make a close up picture of the structure than?
Johannes - here is another one - there is a fairly clear association with the base of the "funnel" structure and a "chondrites" horizon. The infill of the Chondrites is the same colur and texture as the infill of the funnel
I agree with JK, this is the sedimentary structure. Probably in the 3D shape of the funnel.
What sedimentary structure forms funnels? Why the association with Chondrites? Here is another to consider...
Syntectonics can cause funnel structures in different ways. Also erosional structures might be possible. In your last picture it seems that below the "funnel" (you have it only in a twodimensional view?) the layers are arched upwards, so you should also think about the possibility of desiccation or dewatering structures.
At the moment I see no clear evidence for the suggestion these are trace fossils.
Did you have and can supply close ups of the Chondrites?
Dessication not possible these are marine sediments - Chondrites follows. Dewateing is possible - certainly an unstable shelf environment
Some of my colleagues published a paper (in german) about conical structures and Conichnus:
https://www.researchgate.net/publication/235410654_Kegelfrmige_organische_und_anorganische_Strukturen_in_unterkambrischen_Sandsteingeschieben_Norddeutschlands_-_Cone-like_organic_and_inorganic_structures_in_Lower_Cambrian_Sandstone_Geschiebe_of_Northern_Germany?ev=contentfeed
Some of the figures and the cited references might be helpful. Please keep in mind: you see only 2-dimensional pictures of the structure. Unless you havn't seen one (or some) in horizontal sections, you shouldn'd be fixed on a conical structure, also channel-like structures could be possible and open additional interpretations of the structures origin.
Best regards
Johannes
Article Kegelförmige organische und anorganische Strukturen in unter...
Johannes - Thank you for your interest and the information above - I shall certainly have a read and review. I am fully aware of the 3D possibilities - but don't get much chance to see horizontal sections of the critical rocks..
Hi Johannes - I think I see it......can you translate what it says about Plates D and F on page 103.? Thanks again for your interest
Hello Keith,
I hope my translation is usable:
"B: top view of the fossil surface layer with numerous relatively small funnels. D cross-section with two distinct tubes and slightly recurved stratification, which ends in two funnels near the surface layer. F close up of the left funnel with enrichment of pyrite crystals and good developed stratification."
Best regards
Johannes
Johannes - Brilliant - Dankeshun Grosse - if you know what I mean!
As to me it is a sedimentological "story", instead of beeing a trace fossil.
- Badges
- Science topic
- Similar topics
- Biological Science
- Zoology
- Ornithology