Nutrification-related anoxia primed metazoan reefs for their ultimate Frasnian-Famennian collapse in the Alberta Basin, Canada

Abstract

The collapse of metazoan carbonate reefs during the Late Devonian Period is commonly attributed to ocean anoxia, yet the exact mechanisms that caused this and the long-term decline of marine ecosystems are debated. This study integrates sedimentology, palaeontology, and trace and rare earth element geochemistry to determine palaeoenvironmental conditions during the growth of Frasnian reefs in the Alberta Basin, Canada. Middle to late Frasnian stromatoporoid-dominated reefs exhibit negative Ce/Ce* (mean 0.73) and elevated redox-sensitive trace element (U, V, Mo) concentrations indicative of predominantly well‑oxygenated conditions, but also exhibit positive Eu/Eu* (mean 1.41) and low chalcoph..