Volcanosedimentary paleoenvironments of Ediacaran fossils in Newfoundland

摘要: A new perspective on paleoenvironments of Ediacaran fossils the upper Conception Group (Newfoundland) comes from geochemical and sedimentological study volcanic tuffs sedimentary rocks. Tuffs in have major- trace-element compositions U-Pb ages comparable with those source volcanics nearby Burin Bonavista Peninsulas islands St. Pierre Miquelon. Loss silica alkalies some ashes indicates weathering land, not marine diagenesis. Volcanic crystal lapilli fail to show grading highly vesicular scoria scattered a fine-grained matrix, so they were deposited water. These as well block-and-ash flows, spindle bombs, degassing features are evidence eruptions subaerial edifices. The fossiliferous accumulated within forearc basin, formed continental crust, inboard Holyrood horst, uplifted part an ancient subduction complex or accreted terrane. Like analogous basins Oregon-Washington, southern Chile, Japan, includes only bay turbidites, but also variety intertidal terrestrial tsunamites, seismites, tempestites, paleosols. Traditional turbidite models explain deposition Mall Bay, lower Drook, Briscal Formations Group, Gaskiers, Briscal, Mistaken Point coastal plains zones. Paleoenvironments vendobiont preserved life position Newfoundland marginal marine, deep sea.