Grainstone

Thin-section of a grainstone with calcitic ooids; Carmel Formation, Middle Jurassic, of southern Utah, USA.

Grainstone (Brassfield Formation near Fairborn, Ohio, USA). Grains are crinoid fragments.

Under the Dunham classification, grainstones are grain-supported carbonate sedimentary rocks that contain no micrite. The spaces between grains are filled with sparry cement.

References

Dunham, R.J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W.E., ed., Classification of carbonate rocks: American Association of Petroleum Geologists Memoir 1, p. 108-121.

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