Episodic intensification of marine phosphorus burial over the last 80 million years.

Abstract

Marine phosphatization events cause episodic carbonate fluorapatite (CFA) precipitation on seamounts, and are commonly linked to growth hiatuses in ferromanganese (Fe-Mn) crusts. However, the complete record of these events and their paleoenvironmental significance remains poorly understood, in large part due to poor age constraints. Here, we apply U-Pb dating to CFA in Fe-Mn crusts from Western Pacific seamounts. These data exhibit good alignment with Sr isotope ages, revealing six potential phosphatization events. This established CFA chronology tightens the timespan of phosphatization events and refines the age framework of Fe-Mn crusts. We subsequently utilize a multiproxy approach to demonstrate that the phosphatization events occurred coeval with the expansion of oceanic oxygen minimum zones. The Western Pacific Fe-Mn crusts thus document major perturbations in global oceanic phosphorus cycling, which appear to have been driven by climate-induced increases in primary productivity linked to changes in global ocean circulation.