Geochemistry of Neoproterozoic black shales from Svalbard: Implications for oceanic redox conditions spanning Cryogenian glaciations

摘要: Abstract We present paleoredox data from black shales the ca. 835–630 Ma Akademikerbreen and Polarisbreen groups, northeastern Svalbard. These iron speciation, trace metal, organic carbon include first record of ocean redox conditions leading up to Sturtian glaciation contribute emerging narrative protracted Neoproterozoic oxygenation. Sampled were deposited under dominantly suboxic anoxic-ferruginous on a stable continental shelf. Together with other basins, these show no evidence dramatic increases in environmental oxygen levels prior or following glaciation. Proposed global oxygenation aftermath Marinoan did not lead long-term shelf environments Svalbard northwestern Canada. suggest that this reflects sufficient matter loading maintain anoxic water columns margins. In contrast, concentrations may have been higher low-productivity zones further offshore, where downwelling oxygenated surface waters even increased deep ocean.