Peloidal sediments and crusts form up to 75 percent of framework limestones in Upper Triassic reefs in the Yukon Territory. The peloids are spherical to irregular in shape, 20-250 mu m in size, and are commonly surrounded by one or more rims of sparry calcite. The peloidal sediments occur in confined cavities and in open spaces between reef framebuilders; the peloidal crusts generally coat calcareous sponges and tabulozoans. Internal evidence suggests that the peloids are not detrital grains or fecal pellets, and comparisons with Mg calcite peloids and peloidal crusts in modern environments suggest that they are precipitates, possibly resulting from bacterial activity.

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