Radial Ooids - Girvanella, Trilobites & Crinoids - Carboniferous (0/34/Carb/Aus)
10x
|
2.5x
|
20x
|
5x
|
5x
|
2.5 cross nicols
|
5x cross nicol
|
5x cross nicol
|
2.5 wave plate
|
5x wave plate
|
5x wave plate
|
Outstanding feature |
Radial ooids, girvanella, trilobites and crinoids with spar overgrowths |
Folk Classification |
Echinoidal Oosparite |
Dunham Classification |
Echinoidal Oolitic Grainstone |
Common Grains |
Ooids, echinoids, and trilobites |
Sorting |
Good |
Rounding |
Good |
Micritization & envelopes |
Little micritization |
Cement & diagenetic fabric |
Equant spar overgrowths on echinoids |
Porosity |
None |
Depositional Setting |
Open marine high energy setting |
Diagenetic history |
Large equant spar overgrowths |
The ooids are interpreted to have accumulated in a high energy open marine setting. Note how the ooids are almost spherulitic in character. The darkened spots within ooid cortex or layers are after cyanobacteria colonies that caused the local micritization. Note the beautiful overgrowths on the crinoid fragments and the neat trilobite hash!!! There is even a colony of Girvanella skulking in the thin section!
Thursday, November 11, 2021