Stable tungsten isotopic composition of seawater over the past 80 million years

Abstract The isotopic composition of seawater provides valuable information on how the Earth system has evolved. Here we present stable tungsten (δ186/184W) recorded in three ferromanganese (Fe-Mn) crusts spanning past 80 million years Pacific. δ186/184W Fe-Mn displays a pronounced decrease ∼0.2‰ from 60 Ma to 40 followed by value ∼0‰ since ca. Ma. Multiple lines evidence indicate an invariable equilibrium fractionation between and seawater. consistent variations also limited alteration deposition regime or diagenetic overprinting. Thus, reflects mainly that A simple mass-balance calculation comparison other proxies suggest early Cenozoic was most likely caused decreased W sinks linked shifting sedimentation regimes. We propose increased burial organics oxide (FMO) may result smaller associated with limiting adsorption water column onto FMOs openocean sediments. Our results demonstrate potential as novel paleo-proxy for global biogeochemical cycling.