Ooids ( O/1/ )
2.5x
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2.5x cross nicols
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2.5x wave plate
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5x
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5x wave plate
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5x
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5x wave plate
|
10x
|
10x wave plate
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10x
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10x
|
Outstanding feature | High energy radial ooids & quartz - in with thin isopachus and equant cement |
Folk Classification | Well sorted quartzose oosparite |
Dunham Classification | Well sorted quartzose oograinstone |
Common Grains | Ooids, &quartz |
Sorting | Well sorted |
Rounding | Well rounded |
Micritization & envelopes | A few coated grains |
Cement & diagenetic fabric | Isopachus cement, interpenetration of ooids before final passive equant spar |
Porosity | None |
Depositional Setting | High energy shoal |
Diagenetic history | Freshwater isopachus cement |
Striking high energy ooid grains within spar cement matrix. Radial calcitic ooid cortex is concentricly layered about nucleae of both quartz and micritic pelloids. Darkened spots within ooid layers and micrite envelopes are cyanobacteria colonies that caused local micritization when high energy grains came to rest in this setting. In some parts of thin section common points of contact between ooids show some interpenetration and disolution at ooid grain boundaries.
Thursday, November 11, 2021