Linking phosphogenic episodes on the southeast U.S. margin to marine δ¹³C and δ¹⁸O records Available to Purchase

The relative abundance of phosphorite as a function of age was estimated for the southeastern United States using ⁸⁷Sr/⁸⁶Sr derived ages. The Sr-derived ages define seven phosphogenic episodes on the northeast Florida platform. Phosphorus burial rate estimates for the southeastern United States margin range from 2 to 12 × 10⁹ mol ṁ P ṁ yr⁻¹, and phosphorus accumulation rates range from 1 to 3 µmol ṁ cm⁻² ṁ yr⁻¹, similar to modern phosphogenic margins. The estimated amount of organic carbon burial ranges from 1 to 12 × 10¹⁶ mol C; sufficient to shift the ocean δ¹³C by 0.1‰ to 0.6‰. On long time scales (>1 m.y.) phosphogenesis in the southeastern United States corresponds to increased organic carbon burial (positive δ¹³C shifts) and rising sea level (negative δ¹⁸O shifts). On shorter time scales (<1 m.y.), the correlation of phosphogenesis to positive δ¹³C and δ¹⁸O shifts suggests a different relation between phosphogenesis, organic carbon burial, eustasy, and climate transitions during the Miocene.