Ooid - Cortex Layers Brittle, Compact & Break - Cretaceous (O/38/K/Tx)
Outstanding feature |
Radial ooids |
Folk Classification |
Well sorted oosparite |
Dunham Classification |
Well sorted oograinstone |
Common Grains |
Ooids |
Sorting |
Well sorted |
Rounding |
Well rounded |
Micritization & envelopes |
Some micritized borings into radial fabric |
Cement & diagenetic fabric |
Thin equant rims and final spar fill |
Porosity |
Intercrystalline |
Depositional Setting |
High energy but restricted shoal |
Diagenetic history |
Equant calcite is a final spar fill |
Calcitic ooid grains that accumulated on high energy shoals. Sparse isopachus rim cements are calcite. Ths final void fill cementation is low magnesian calcite equant spar. Some of the spar is penetrating and replacing the ooids. The calcite cement was probably derived from earlier aragonitic material. The ooids are interpenetrating and have peloids nucleae. Ooid layers or cortex become brittle and locally break off the surfaces of the ooids under compaction.
Thursday, November 11, 2021