Ooids

1. Ooids

Tangential, originally aragonitic ooids with early marine isopachous rims of fibrous cements. Ooid nuclei are gastropods, quartz grains and peloids (high-energy shoal, Recent).

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

2. Ooids

View in crossed polarisers of present-day tangential ooids. The interference colours and figures are visible. The grainstone is cemented by early marine isopachous rims of fibrous cement.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

3. Ooids

Concentric radial ooids (originally HMC?) in a grainstone with micritised grains, peloids and foraminifera Trocholina. Ooid nuclei are peloids and detrital quartz grains (high-energy shoal).

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

4. Ooids

Radial ooids (proginally HMC?) in a grainstone with thin isopachous rims of marine cement (pink due to staining with alizarin red) and burial blocky sparite (blue-coloured ferroan calcite due to staining with potassium ferricyanide).

Pennsylvanian, Asturias, N Spain, cf. Bahamonde et al. (2015, 2017)

5. Ooids

Radial ooids in a packstone to grainstone, compacted and with concave-convex grain contacts. Nuclei of ooids are bioclasts (red alga Komia, bryozoans and foraminifera; back-shoal, lagoon).

Pennsylvanian, Asturias, N Spain, cf. Bahamonde et al. (2015, 2017)

6. Ooids

Resedimented ooids in a packstone associated with lithoclasts; ooids show an additional micritic coating due to algal-microbial encrustations.

7. Tangential Aragonite Ooids

Tangential originally aragonitic ooids from Recent tropical carbonate settings in the Bahamas. Field of view 2 mm.

Bahamas, Holocene

8. Tangential Aragonite Ooids

Recent ooids from hypersaline lake develop radial fabric of aragonite mineralogy in contrast with the typical tangential aragonitic ooids precipitated in modern tropical marine environments.

Promontory Point, Great Salt Lake, Utah, USA

9. Radial Aragonite Ooids

Deposits from the hypersaline Great Salt Lake showing radial aragonitic ooids, peloids and intraclasts bound by a micrite crust at the top.

Bridger Bay, Antelope Island, Great Salt Lake, Utah, USA

10. Radial Aragonite Ooids

Sediment from present-day beach of a hypersaline lake including radial aragonitic ooids (with detrital quartz nuclei) and peloids, among which common faecal pellets.

Promontory Point, Great Salt Lake, Utah, USA

11. Radial Aragonite Ooids

Thin section of an intraclast composed of ooids. Some ooids appear cemented by overgrowths of their radial aragonite crystals.

Bridger Bay, Antelope Island, Great Salt Lake, Utah, USA

12. Radial Aragonite Ooids

Sediment from present-day hypersaline lake shoreline including radial aragonitic ooids and peloids, among which common faecal pellets and intraclasts.

Promontory Point, Great Salt Lake, Utah, USA

13. Radial Aragonite Ooids

Stained thin section of an intraclast of ooidal sand cemented by aragonite with meniscus and isopachous growth habit. Sample deriving from present-day beach at Great Salt Lake, Utah.

Bridger Bay, Antelope Island, Great Salt Lake, Utah, USA

14. Micritized Calcite Ooids

Micritized ooid and aggregate grain packstone formed by resedimented ooids, intraclasts and aggregate grains from the Middle Jurassic of Mallorca. Ooids were deposited in deep-water aprons and reworked from a nearby platform margin.

Middle Jurassic, Cutri, Mallorca, Spain

15. Ancient Aragonite Ooids

Oomouldic grainstone formed by dissolved former aragonitic ooids within a dolomite cement from Upper Triassic lacustrine deposits in Southwest England, UK. Aragonitic ooids, completely dissolved during diagenesis, formed along a lake shore in a saline lake. Field of view approximately 3 mm.

Upper Triassic, Clevedon, UK (cf. Milroy and Wright, 2002)

16. Compound Ooids

Compound ooids and intraclasts in an ooidal grainstone.

Cambrian, Newfoundland, Canada

17. Compound Ooids

Compound ooids and intraclasts in an ooidal grainstone.

Cambrian, Newfoundland, Canada

18. Radial Ooids

Grainstone with radial ooids with some aggragte grains of ooids.

19. Tangential Ooids

Modern tangential ooids from the Egyptian coast.

Recent, Egypt

20. Radial Ooids

Grainstone with radial ooids. Note the clear sparite cement in this ooidal grainstone.

21. Radial Ooids

Grainstone with radial ooids with clear sparite cement. Note that micritisation has taken place forming a micrite rim around the ooids.