Skolithos pipe rock and associated ichnofabrics from the southern Rocky Mountains, Canada: colonization trends and environmental controls in an early Cambrian sand-sheet complex

The Lower Cambrian Gog Group of the southern Rocky Mountains of western Canada offers an opportunity to explore animal-sediment relationships in a high-energy setting, during the early phase of Phanerozoic diversification. Its strata record a sand-sheet complex on the broad pericontinental shelf of West Laurentia. Six ichnofabrics are recognized: Skolithos IF-1 characterized by Skolithos linearis in planar cross-stratified sandstone; Skolithos IF-2 with Skolithos linearis and accessory Diplocraterion parallelum in ripple cross-laminated, and planar and trough cross-stratified sandstone; Skolithos IF-3 with S. linearis and Planolites montanus in wavy- and flaser-bedded sandstone, interfingering with bioturbated mudstone exhibiting P. montanus and Teichichnus rectus; Skolithos IF-4, characterized by abundant Skolithos linearis in planar and trough cross-stratified sandstone; Rosselia IF-1 consisting of Rosselia isp. in planar cross-stratified sandstone; and Rosselia IF-2 consisting of scattered small Rosselia isp. in hummocky, cross-stratified sandstone. The presence of contrasting ichnofabrics within a single early Cambrian sand-sheet complex illuminates how the colonization trends of suspension and detritus feeders were controlled by factors specific to the various sub-environments. square Gog Group, Ichnofabric, Lower Cambrian, Pipe Rock, Rosselia, Skolithos.