Enrichment of dissolved silica in the deep equatorial Pacific during the Eocene-Oligocene
Silicon isotope ratios (expressed as δ30Si) in marine microfossils can provide insights into silica cycling over geologic time. Here we used δ30Si of sponge spicules and radiolarian tests from the Paleogene Equatorial Transect (Ocean Drilling Program Leg 199) spanning the Eocene and Oligocene (~50-23 Ma) to reconstruct dissolved silica (DSi) concentrations in deep waters and to examine upper ocean