Marine biogeochemical cycling during the early Cambrian constrained by a nitrogen and organic carbon isotope study of the Xiaotan section, South China

Isotopic evidence for water-column denitrification and sulfate reduction at the end-Guadalupian (Middle Permian)

“…Generally, the δ 15 N value of the organic matter in the sediments would increase due to a preferential 14 N loss during burial and early sedimentary diagenesis, including thermal maturation (e.g., Altabet and Francois, 1994;Williams et al, 1995;Jia and Kerrich, 2004;Robinson et al, 2012); in that case, a negative correlation between the δ 15 N value and the TN content in the sedimentary records would be expected (Cremonese et al, 2013). No strong negative correlation between the δ 15 N values and the TN contents is observed in the analyzed samples at Chaotian (Fig.…”

Marine redox variations and nitrogen cycle of the early Cambrian southern margin of the Yangtze Platform, South China: Evidence from nitrogen and organic carbon isotopes

“…Given that the nitrogen cycle is not only closely related to marine environmental conditions and biological metabolism, but also reflects the ocean redox structure, an increasing number of studies have been conducted on the nitrogen isotope systematics of Ediacaran -early Cambrian marine sediments (Ader et al, 2014;Cremonese et al, 2013Cremonese et al, , 2014Kikumoto et al, 2014;Wang et al, 2013). However, these studies mainly focused on the shallow platform realm.…”

Secular changes of water chemistry in shallow-water Ediacaran ocean: Evidence from carbonates at Xiaofenghe, Three Gorges area, Yangtze Platform, South China

“…Paleo-seawater pH is inferred from boron isotope compositions (Kasemann et al, 2005;Ohnemueller et al, 2014). Other isotope systems such as Si, N, and Zn isotopes have also been used to study the effect of the biological fractionation of these stable isotope systems during the onset of complex multicellular life (Kunzmann et al, 2012;Cremonese et al, 2013;Ader et al, 2014;Fan et al, 2013). S, Fe, Mo and Cr isotopic compositions as well as iron speciation and redox-sensitive trace element analysis (Canfield et al, 2008;Zhou and Jiang, 2009;Frei et al, 2011;Wen et al, 2011;Pi et al, 2013;Fan et al, 2014) were used to gather information about paleo-seawater redox conditions and to test recent models of a proposed stratified Ediacaran ocean .…”