Peloids

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File:PeloidsCarboniferousNV.jpg
Peloids and a brachiopod shell visible in a limestone thin-section; Bird Spring Formation (Carboniferous) of southern Nevada.

Peloids are fecal pellets that are produced by organisms that consume calcium carbonate mud. They are formed from organism excretions of undigested calcium carbonate mud. Peloids tend to be oval in shape and uniform in size. They are smaller than ooids and tend to be no larger than a silt to fine-sand size. Unlike ooids, peloids lack concentric and radial internal structures, making them easy to distinguish from ooids and other non-skeletal grains. Instead of being identified by an internal structure, like ooids, peloids can be identified by their dark color due to the organic matter from which they are formed.

Depositional environment

Peloids collect in lagoons and shallow intertidal zones where they are protected from rough ocean currents. However, peloids will not remain protected forever and will eventually break down into micrite. Through burial processes, peloids will become cemented and preserved.

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