A sedimentary record of the evolution of the global marine phosphorus cycle

Abstract

Phosphorus (P) is typically considered to be the ultimate limiting nutrient for Earth's biosphere on geologic timescales. As P is monoisotopic, its sedimentary enrichment can provide some insights into how the marine P cycle has changed through time. A previous compilation of shale P enrichments argued for a significant change in P cycling during the Ediacaran Period (635-541 Ma). Here, using an updated P compilation-with more than twice the number of samples-we bolster the case that there was a significant transition in P cycling moving from the Precambrian into the Phanerozoic. However, our analysis suggests this state change may have occurred earlier than previously suggested. Specifically in the updated database, there is evidence for a transition ~35 million years before the onset of the Sturtian Snowball Earth glaciation in the Visingsö Group, potentially divorcing the climatic upheavals of the Neoproterozoic from changes in the Earth's P cycle. We attribute the transition in Earth's sedimentary P record to the onset of a more modern-like Earth system state characterized by less reducing marine conditions, higher marine P concentrations, and a greater predominance of eukaryotic organisms encompassing both primary producers and consumers. This view is consistent with organic biomarker evidence for a significant eukaryotic contribution to the preserved sedimentary organic matter in this succession and other contemporaneous Tonian marine sedimentary rocks. However, we stress that, even with an expanded dataset, we are likely far from pinpointing exactly when this transition occurred or whether Earth's history is characterized by a single or multiple transitions in the P cycle.

Evolution of the crustal phosphorus reservoir

“…In another case, our results help to resolve discrepancies between previous studies of ancient P cycling, namely, disagreement on the robustness of apparent increases in sedimentary P content across the Neoproterozoic-Phanerozoic boundary ( 33 ). Reinhard et al.…”

“…In another case, our results help to resolve discrepancies between previous studies of ancient P cycling, namely, disagreement on the robustness of apparent increases in sedimentary P content across the Neoproterozoic-Phanerozoic boundary (33). Reinhard et al (32) suggest a Neoproterozoic increase in siliciclastic P content related to increased marginal P-burial and oxidant-driven P recycling.…”

Nitrate limitation in early Neoproterozoic oceans delayed the ecological rise of eukaryotes

“…800 Ma coincides with breakup of supercontinent Rodinia and implies increasing marine nitrate availability. ( B ) Phosphorus concentrations of marine siliciclastic sediments through time ( 13 , 79 ). LOWESS regression is based on the entire dataset.…”

“…For the time series data, changepoint detection aims to estimate the point at which the statistical properties of this dataset change based (13,79). LOWESS regression is based on the entire dataset.…”

Tonian Carbonates Record Phosphate‐Rich Shallow Seas

“…A more recent analysis of an expanded database suggests that the P concentration of shales began to increase earlier than previously thought (ca. 750 Ma; Planavsky et al., 2022). Utilizing a different approach, Guilbaud et al.…”