Origin of Coated Grains: Trace Element Constraints

Coated grains, which may have skeletal cores, are non-skeletal carbonate and non-carbonate grains formed in marine as well as non-marine environments. These grains are classified according to their structure and environmental parameters (Peryt, this vol.). Peloids are micritic grains without recognizable structures and are represented by individual grains and aggregates. Ooids, oncoids, rhodoids, and vadoids are coated grains with distinct structural features.