Devonian-carboniferous Hangenberg mass extinction event, widespread organic-rich mudrock and anoxia: Causes and consequences

摘要: Abstract The Hangenberg Bio-event represents one of the largest Phanerozoic mass extinction events. It is not only recorded by changes in faunal composition affecting all trophic levels (in terrestrial and marine environments), but also recognized lithological geochemical just prior to Devonian–Carboniferous (D–C) boundary. This global crisis occurs at base a globally extensive black, organic-rich mudrock which sharply gradationally overlies ramp platform carbonates. Together with positive excursions S, O, C, Sr isotope curves, dramatic changes, D–C boundary, imply an episode climatic perturbation. A low-latitude continuum organic carbon generation burial evidenced formation organic- phosphatic-rich black mudrocks, specific deviations disappearance nektobenthic organisms, diversification small-eyed or blind trilobites, appearance primary producers zooplankton accustomed nutrient-rich conditions. proposed that oceanic overturn subsequent eutrophication resulted heightened productivity, development benthic anoxia biotic demise forms. Gradual cooling leading `mini'-glaciation Gondwana was driving force conditions mixing eutrophication.