Nitrogen cycling during the peak Cambrian explosion

Previous studies on early-Cambrian nitrogen (N) cycle suggested a modern-type nitrogen reservoir with elevated nitrate (NO3−) availability in a globally oxygenated ocean for the Cambrian explosion. However, recent marine redox studies on the Chengjiang Biota revealed a stratified ocean with anoxic d...

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Bibliographic Details
Published in:Geochimica et cosmochimica acta 2022-11, Vol.336, p.50-61
Main Authors: Chang, Chao, Wang, Zhenfei, Huang, Kang-Jun, Yun, Hao, Zhang, Xingliang
Format: Article
Language:English
Subjects:
Cambrian Age 3
Cambrian explosion
Nitrogen cycle
NO3− reservoir
Qingjiang Biota
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Summary:Previous studies on early-Cambrian nitrogen (N) cycle suggested a modern-type nitrogen reservoir with elevated nitrate (NO3−) availability in a globally oxygenated ocean for the Cambrian explosion. However, recent marine redox studies on the Chengjiang Biota revealed a stratified ocean with anoxic deeper waters for the peak Cambrian explosion, asking for further works on the N cycling during this critical period. Chengjiang and Qingjiang biotas are the two top-rank Burgess Shale-type fossil Lagerstätten that recorded peaked metazoan diversification of the Cambrian explosion at different paleoenvironmental regimes during the Cambrian Age 3. In this study, we conducted a detailed geochemical investigation of the early-Cambrian Shuijingtuo Formation from two drill cores containing the Qingjiang Biota in Hubei Province, South China. The results suggest progressive oxygenation of the depositional environment from euxinic to fluctuating, suboxic conditions with a low chemocline in the water column, accompanied by an increase of δ15N values from
ISSN:0016-7037
1872-9533
DOI:10.1016/j.gca.2022.09.013