Structural control of Cambrian paleotopography and patterns of transgression in western Laurentia

The Cambrian transgression across the Great Unconformity produced one of largest expansions shallow marine habitats and associated diversification invertebrate faunas in Earth history. However, identification underlying controls on pattern seas has been hampered by imprecise or inaccurate age assignments for many formations. Recovery an Ehmaniella Zone trilobite fauna from Lodore Formation northwestern Colorado (United States) revises this unit to be significantly older, specifically middle Miaolingian (upper Wuliuan). This expands established distribution thick deposits northern Rocky Mountains within 90 km a broad region central where strata are missing Furongian successions rest directly basement. boundary between these two regions marks position ~200 east-west offset generally north-south–trending paleoshoreline western North America. is co-located with Precambrian continental suture zone (Cheyenne belt) at Yavapai terrane margin east similar magnitude latitude early Paleozoic shelf edge Nevada. We thus posit that deep-seated crustal-scale features controlled paleotopography Laurentia, strongly influencing patterns structure ecosystem during submergence. These continental-scale structural elements remained major control paleogeography >200 m.y. into late Paleozoic.