Tracking Cretaceous to present day deep-sea sedimentary hiatuses driven by intensified bottom-water currents

Increased deep-sea paleocurrents are thought to be intimately associated with sedimentary hiatuses, which result in missing or mixed information on sediment ages, paleoproductivity, and marine chemistry and redox conditions. However, tracing paleocurrent evolution based on sedimentary hiatuses is challenging due to poor age constraints and the limited archive. Here, we investigate authigenic carbonate fluorapatite (CFA) grains from winnowed foraminiferal sand on Western Pacific guyots. The CFA grains are distinct from heavily reworked, cryptocrystalline continental margin phosphorites, exhibiting well-preserved euhedral crystals that indicate in-situ seamount formation. We apply LA-ICP-MS U-Pb dating to these CFA grains, revealing discrete ages from the Cretaceous to Oligocene (139.3 to 21.7 Ma), in contrast to the previously identified maximum age of seamount CFA of ∼72 Ma. This fills a temporal gap in seamount phosphogenesis from ∼140–80 Ma, representing the oldest and longest record of seamount phosphogenesis events yet documented. The pulsed enhancement of CFA formation temporally corresponds to both sedimentary disconformities at the nearby ODP Site 866, and global oceanic sedimentary hiatuses. Our results suggest that CFA forms episodically when climate-driven paleocurrents accelerate abruptly, preventing sediment accumulation in the deep ocean but promoting nutrient upwelling to the seamount top. Our data thus highlight the utility of seamount CFA as a tracer for documenting the timescales of enhanced paleocurrents and consequent sedimentary hiatuses.