Carbonate-associated phosphate evidence for a small inorganic phosphorus reservoir in the terminal Ediacaran ocean (original) (raw)

Abstract

The terminal Ediacaran (ca. 551–533 Ma) was characterized by profound biological innovations and environmental upheavals, in which phosphorus (P)—the ultimate limiting nutrient for marine productivity—is postulated to have played a key role. However, P availability in the terminal Ediacaran ocean remains uncertain due to the lack of an appropriate proxy record. To better reconstruct seawater P levels during this time interval, we analyzed carbonate-associated phosphate [CAP; expressed as CAP/(Ca + Mg)], a new proxy for P availability in ancient oceans, in three upper Ediacaran successions: the Nama Group (Namibia), the Shibantan Member of the Dengying Formation (Wuhe, South China), and the Algal Dolomite, Gaojiashan and Beiwan members of the Dengying Formation (Gaojiashan, South China). Our results reveal consistently low CAP/(Ca + Mg) values (range: 0.02–0.69 mmol/mol, mean: 0.13 ± 0.01 mmol/mol, 2σ, the same below) for all study sections, falling at the lower end of modern marine carbonate values. Lithofacies, carbonate oxygen isotopes, Mn/Sr and Mg/(Mg + Ca) ratios indicate possible influences from release of Fe-bound P, meteoric diagenesis, recrystallization or dolomitization. The low CAP/(Ca + Mg) values thus represent a maximum estimate for the seawater P availability. The low CAP values from two geographically separated cratons likely reflect a generally small oceanic inorganic P reservoir at least in shelves. This study provides insights into the interplay between nutrient cycling, redox dynamics, and biological evolution during one of the most pivotal transitional periods in Earth history.

Citation

Fan, Y, Cheng, M, Chen, X, Rose, C, Wang, H, Zhang, Z, Algeo, T J & Li, C 2026, 'Carbonate-associated phosphate evidence for a small inorganic phosphorus reservoir in the terminal Ediacaran ocean', Global and Planetary Change, vol. 258, 105284. https://doi.org/10.1016/j.gloplacha.2026.105284

Publication

Global and Planetary Change

Rights

Copyright © 2026 the Authors. This work has been made available online in accordance with the University of St Andrews Open Access policy. This accepted manuscript is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The final published version of this work is available at https://doi.org/10.1016/j.gloplacha.2026.105284

Description

Funding: This research is financially supported by NSFC, and the Key R&D Project of the Ministry of Science and Technology (42130208, 2022YFF0800100, 42425002, 42572399, 42002027).