The end Triassic mass extinction record of Williston Lake, British Columbia

An 80 million year oceanic redox history from Permian to Jurassic pelagic sediments of the Mino-Tamba terrane, SW Japan, and the origin of four mass extinctions

“…Similar, time averaging has been inferred in other ancient studies (e.g. Wignall and Newton, 1998;Bond et al, 2004;Wignall et al, 2007;Bond and Wignall, 2010). Perhaps the poorest appreciation of redox conditions using the pyrite framboid technique comes from environments subject to high amplitude redox changes.…”

Oceanic redox conditions in the Late Mesoproterozoic recorded in the upper Vazante Group carbonates of São Francisco Basin, Brazil: Evidence from stable isotopes and REEs

“…5). The preglacial ␦ 13 C carb plunge is correlated with a negative Ce/Ce * shift of ∼0.4, suggesting reducing conditions (e.g., Holser et al, 1989;Shields et al, 1997), which is consistent with their low (<2) Th/U values (Wignall and Twitchett, 1996;Wignall et al, 2007). In contrast, the lower postglacial plunge in ␦ 13 C carb , immediately above the diamictite (D II), is correlated with a significant positive Ce/Ce * shift of ∼1.5 (Fig.…”

“…Levels of oxygen in the water column, expressed as the redox conditions, influence the oxidation state of some elements and selectively control their solubility in seawater and consequently their degree of enrichment in marine sediments (e.g., Myers and Wignall, 1987;Wignall and Twitchett, 1996;Arnaboldi and Meyers, 2007;Wignall et al, 2007). Uranium is among the elements which are sensitive to redox conditions in seawater.…”

“…Preserved marine carbonates are known to retain their primary chemical, elemental and isotopic, signatures that reflect the effect of prevailing oceanographic conditions and patterns (e.g., Wignall and Twitchett, 1996;Shields et al, 1997;Azmy et al, 1998;Veizer et al, 1999;Arnaboldi and Meyers, 2007;Wignall et al, 2007). Anoxic conditions have a dramatic impact on the organic productivity in oceans and, in most cases, may result in global mass extinction events (e.g., Wignall and Twitchett, 1996).…”

Late Triassic sedimentary evolution of Slovenian Basin (eastern Southern Alps): description and correlation of the Slatnik Formation

“…Although the mechanisms that led to the extinction are still debated, two processes that mark the boundary are common to all studied sections: (1) the biocalciWcation crisis at the end of the Triassic followed by recovery in the Hettangian (Pálfy et al 2001(Pálfy et al , 2007Ward et al 2001Ward et al , 2004Galli et al 2005Galli et al , 2007Ciarapica and Passeri 2005;Ciarapica 2007; Van de Schootbrugge et al 2007) and (2) a sea-level drop coupled with subsequent transgression at the boundary or slightly preceding it. The second event is reported globally (McRoberts et al 1997;Hallam 1997;Hesselbo et al 2002Hesselbo et al , 2004Guex et al 2004;Galli et al 2005;Ciarapica and Passeri 2005;Jadoul et al 2005Jadoul et al , 2007Krystyn et al 2005;Ciarapica 2007;Wignall et al 2007). …”