The Frasnian–Famennian biotic crisis: How many (if any) bolide impacts?

Sequence stratigraphic and genetic aspects of the Tournaisian "Liegender Alaunschiefer" and adjacent beds

“…Global cooling, on the other hand, would improve oceanic ventilation and thus recycle previously unavailable nutrients stored in the deep ocean (Berry and Wilde 1978). Racki (1999) alternatively suggested primary nutrient replenishing by early Variscan volcanic and hydrothermal activity as major control of the Frasnian-Famennian crisis.…”

“…Although conclusive evidence is scarce, the importance of volcanic sources for the Devonian through Early Carboniferous ocean water chemistry and phosphogenesis has previously been stressed by Zimmerle (1992) and, more recently, by Racki (1999). Hydrothermal circulation, on the other hand, effectively removes phosphate rather than adding it to the ocean water (Wheat et al 1996).…”

“…10, 2). Eutrophication was probably caused by the joint effect of at least three environmental nutrient sources: (1) enhanced upwelling through new gateways for upwelling currents in consequence of rising sea level (Jenkyns 1988); (2) progressive ventilation of the ocean under cooler climate conditions (Berry and Wilde 1978); and (3) increased volcaniclastic nutrient input (Racki 1999). Contributions of other mineral sources, e.g.…”

“…In the Early Carboniferous, however, the Rhenohercynian basin was progressively closed and partly subducted under the Mid-German High, where an active continental margin was located (Franke 1995;Oncken and Weber 1995). Contemporaneous volcanic activity is evident from extrusive deposits and bentonite layers, and it probably influenced ocean water and sediment geochemistry (Racki 1999;Zimmerle and Stribrny 1992).…”

Pioneer organisms after F-F mass extinction in Dushan region, Guizhou Province, and their significance in establishing new ecosystem

“…To know what the pioneer organisms would be and their development, and to trace the establishment process of the ecosystems are of great importance for the study of the biological evolution and recovery in aftermath. As one of the "big five" mass extinctions in the geological history, the Late Devonian Frasnian-Famennian (F-F) event had killed 21% of families, about 50% of the genera [1] , and about 82% of species [2] of the marine benthos, especially in low-latitude shallow seas [1][2][3][4][5][6][7][8] . In the recent 10 years, however, most of the researches have focused mainly on the causes of the mass extinction and the biotic recovery after the extinction, while studies on the pioneer organisms and the reconstruction of a new ecosystem in the aftermath have been rarely dealt with.…”