Paleoenvironmental analysis of Ediacaran strata in the Catalina Dome, Bonavista Peninsula, Newfoundland
Ediacaran strata in the Conception and St. John’s groups that are exposed in the Catalina Dome, eastern Newfoundland, comprise a succession that is thinner but otherwise broadly similar to that known from the well-studied outcrops near Mistaken Point in southern Avalon Peninsula and Spaniard’s Bay in northern Avalon. In all of these areas, strata consist of turbidites deposited in deep-water basin-plain and slope environments, but important differences help to constrain interpretations of basin history and Ediacaran paleobiology of eastern Newfoundland. A turbidite paleocurrent shift from easterly to southerly is consistent with the existing two-phase tectonic model for basin evolution previously proposed for the Avalon Peninsula. In the Catalina Dome, however, this shift occurred stratigraphically higher than at Mistaken Point but lower than at Spaniards Bay in the Avalon Peninsula. Probable seismoturbidites are common in the lower part of the Catalina succession, suggesting particularly active tectonism. Except in the very lowest 20 m of the succession (Drook and lowermost Mistaken Point formations) in which ash is absent, volcanic ash beds are both more common and more volumetrically significant throughout the succession than farther to the south and east, which suggests that deposition occurred closer to the volcanic arc. Volcanic ash beds persist higher stratigraphically, occurring within the Fermeuse Formation, which here contains diverse rangeomorph fossils in contrast with the low-diversity assemblage of Ediacaran discs prevalent in the Fermeuse Formation of the Avalon Peninsula. This distribution strongly reaffirms the importance of taphonomy in controlling the composition of deep-water Ediacaran assemblages.