Redox condition and nitrogen cycle in the Permian deep mid-ocean: A possible contrast between Panthalassa and Tethys
"To constrain the redox conditions and related nitrogen cycles during the Middle Permian (Guadalupian) to latest Late Permian (Lopingian) deep mid-Panthalassa, we determined the abundances of major, trace, and rare earth elements along with the carbon and nitrogen isotope ratios in shales interbedded with deep-sea cherts that are well-exposed at the Gujo-Hachiman section in the Mino-Tanba belt, SW Japan. [...]"
Source: Global and Planetary Change
Authors: Wataru Fujisaki et al.
Coupling of ocean redox and animal evolution during the Ediacaran-Cambrian transition
"The late Ediacaran to early Cambrian interval witnessed extraordinary radiations of metazoan life. The role of the physical environment in this biological revolution, such as changes to oxygen levels and nutrient availability, has been the focus of longstanding debate. Seemingly contradictory data from geochemical redox proxies help to fuel this controversy. As an essential nutrient, nitrogen can help to resolve this impasse by establishing linkages between nutrient supply, ocean redox, and biological changes. [...]"
Source: Nature Communications
Authors: Dan Wang et al.
Heterogenous oceanic redox conditions through the Ediacaran-Cambrian boundary limited the metazoan zonation
"Recent studies have enhanced our understanding of the linkage of oxygenation and metazoan evolution in Early Cambrian time. However, little of this work has addressed the apparent lag of animal diversification and atmospheric oxygenation during this critical period of Earth history. This study utilizes the geochemical proxy and N isotope record of the Ediacaran–Cambrian boundary preserved in intra-shelf basin, slope, and slope basin deposits of the Yangtze Sea to assess the ocean redox state during the Early Cambrian metazoan radiation. [...]"
Source: Scientific Reports
Authors: Junpeng Zhang, Tailiang Fan, Yuandong Zhang, Gary G. Lash, Yifan Li & Yue Wu