It is always difficult to identify a feature by looking into a single photograph. it is also not mentioned whether it is a section of bedding plane. However, it looks like concretions in mudstone. Due to weathering, typical concentric layered pattern is exposed.

It is always difficult to identify a feature by looking into a single photograph. it is also not mentioned whether it is a section of bedding plane. However, it looks like concretions in mudstone. Due to weathering, typical concentric layered pattern is exposed.

Dear Mr. Oluwajana,

I can only support the previous answers to the question which were more a sort of a soft claim of getting more information about the environment of deposition and of the positioning of the image.

It is a clayish matrix and the concentric rings show a slight change in color caused by a variation of the valence state of Fe, due to oxidation. The diameter of the tubular structures lies between that of a tree trunk and a simple root fragment. They are well oriented and as such they might fall into the size range covered by the above floral remains.

Another feature very common in environments abundant in bituminous material belongs to the natural gas seepages which are known from many places such as the Eocene beds of Pobitite Kamani, Bulgaria.

So far there is a lot of uncertainty in my answer due to the lack of information on the internal texture of the tubular or ring-like structures and the host environment. I attach two papers of mine, one from a true coal-bearing environment the other from a transitional environment of the Nepalese Kathmandu Lake, where lignites and bituminous sedimentary rocks occur side-by-side nearshre. Maybe both papers help you to restructure your question and to single out the features you find of assistance in the interpretation of the host environment and the physical-chemical regime.

At the current stage I do not dare to give you a clearer answer.

Best regards

H.G.Dill

Try this reference:

HOSKIN, K.F.G. and PISARSKI, J.B. 1964. Chemical characteristics of the cements

of the Godrevy 10-ft raised beach and of certain deposition pipes in the

St Agnes Pliocene deposits, Cornwall. Transactions of the Royal Geological

Society of Cornwall, 19, 328-348.

Dear Mark, Harald,  Biplab and Peter, I really appreciate your responses and suggestions. Kindly find attached pictures of other structures observed during the mapping exercise. The third picture is 1m thick coal seam.

Dear Mr. Oluwanja,

it seems to be a concretion in one of the argillaceous interbeds quite common in the coal measures worldwide. The entire system is currently strongly oxidized but I suspect of having  primarily developed in a more reducing environment where Fe was present in its bivalent state and contained in siderite or ankerite. It is a type of subeconomic ironstone mineralization belonging in the broadest sense to the so-called clayband deposits. There is a transition from claybands into blackbands depending upon the abundance of goethite and siderite. If you want to use these Fe-bearing layers for sequence stratigraphic purposes I recommend the attached  paper below.

I wish you all the best for your studies

H.G.Dill

Concretion!!

Dear Oladotun 

It look a concretion or  nodules grow within sediment during diagenesis and this may take place below the sediment-water interface.

Good Luck.

It looks like petrified transversal section of tree trunk

Iron ball concretions in fine-grained sandstones

probably associated with a fossil water-table

Dear Mr. Oluwajana,

please release some more data to the audience as to the microstructure and mineralogy. I still maintain my theory on a clayband/ blackband ironstone either in a lacustrine or paralic environment. The hydrologic system plays an important part in the precipitation and transport of Fe, which cannot be carried as an ion but needs so-called chelate complexes common to "Rio Negro" fluvial drainage systems which carry enough organic matter. In case of a break-down of these complexes e.g., at the boundary between freshwater and seawater Fe is forced to precipitate. Even other process of fluid mixing can provoke a similar reaction in terrigeneous environments of deposition.

H.G.Dill

Dear Mr. Oluwajana,

please release some more data to the audience as to the microstructure and mineralogy. I still maintain my theory on a clayband/ blackband ironstone either in a lacustrine or paralic environment. The hydrologic system plays an important part in the precipitation and transport of Fe, which cannot be carried as an ion but needs so-called chelate complexes common to "Rio Negro" fluvial drainage systems which carry enough organic matter. In case of a break-down of these complexes e.g., at the boundary between freshwater and seawater Fe is forced to precipitate. Even other process of fluid mixing can provoke a similar reaction in terrigeneous environments of deposition.

H.G.Dill

Dear Mr. Oluwajana,

please release some more data to the audience as to the microstructure and mineralogy. I still maintain my theory on a clayband/ blackband ironstone either in a lacustrine or paralic environment. The hydrologic system plays an important part in the precipitation and transport of Fe, which cannot be carried as an ion but needs so-called chelate complexes common to "Rio Negro" fluvial drainage systems which carry enough organic matter. In case of a break-down of these complexes e.g., at the boundary between freshwater and seawater Fe is forced to precipitate. Even other process of fluid mixing can provoke a similar reaction in terrigeneous environments of deposition.

H.G.Dill

It looks like a concentric nodule or ironstone concretion as Dr. Dill and Dr. Moreau suggest. There's a smaller one to the right of the pencil.

D. A. Goddard

I think that's not a sedimentary structure, known as a structure formed during deposition. It seems to be an iron oxide concretion as Dr. Dill, Dr. Moreau and Dr. Goddard have suggested.

imentary stucture but some erosional feature

Oladotun Afolabi Oluwajana, are we looking down on the bedding plane, or is the view normal to bedding?  The structure, and the smaller feature of similar shape to the right, do appear to be concretionary, but might also be "tree" trunks in growth position?  Dig into the outcrop and confirm if "spherical"?  Concretions commonly have organic matter of some sort at the center or nucleus.  Might the nucleus be fossilized wood, coal, or charcoal?  Can you take a broom to the surface so that we can see associated bedding structures...that is, are the objects embedded in a  "conglomerate" of sorts?

I agree with the opinion that this could be ironstone concentration

It looks a concretion in mudstone reflecting ferricrete soil feature. In general is oxidizing condition but the concentric alternation reflects change in the conditions, possibly in semi-arid climate.

I too agree with researchers Fayez and Mazin.  We see similar features on fine grain ferrugenious sand stones where they form hard concentric rings. This also appear possibly just exfoliation weathering!! One need to know counts of such structure and their association with host rock which makes things more clear

Probablement un nodule ferrugineux sédimentaire!!!!

Diagenetically formed ferruginous concretions

It consists of an iron oxide concretion.

Article Composition, nucleation, and growth of iron oxide concretions

Cordially yours,

Nadir

Thanks Mohammed