The role of calcium in regulating marine phosphorus burial and atmospheric oxygenation
Mingyu Zhao, Shuang Zhang, Lidya G. Tarhan, Christopher T. Reinhard, Noah J. Planavsky
Abstract
Abstract The marine phosphorus cycle plays a critical role in controlling the extent of global primary productivity and thus atmospheric p O 2 on geologic time scales. However, previous attempts to model carbon–phosphorus-oxygen feedbacks have neglected key parameters that could shape the global P cycle. Here we present new diagenetic models to fully parameterize marine P burial. We have also coupled this diagenetic framework to a global carbon cycle model. We find that seawater calcium concentration, by strongly influencing carbonate fluorapatite (CFA) formation, is a key factor controlling global phosphorus cycling, and therefore plays a critical role in shaping the global oxygen cycle. A compilation of Cenozoic deep-sea sedimentary phosphorus speciation data provides empirical support for the idea that CFA formation is strongly influenced by marine Ca concentrations. Therefore, we propose a previously overlooked coupling between Phanerozoic tectonic cycles, the major-element composition of seawater, the marine phosphorus cycle, and atmospheric p O 2 .