A proxy for reconstructing histories of carbon oxidation in the Northeast Pacific using the carbon isotopic composition of benthic foraminifera (Bolivina argentea, Buliminella tenuata, Bolivina subadvena)

This study reports live foraminiferal distribution and δ 13C, and pore water TCO2, δ13C, and methane in Santa Monica Basin, Santa Barbara Basin, and along the western Mexican margin. Pore water TCO₂ gradients reflect carbon oxidation and CO ₂ diffusion across the sediment-water interface. Carbonate tests of benthic foraminifera from dysoxic, laminated sediments record the 13C/12C composition of pore water TCO₂. Paleo-pore water δ13C profiles can be reconstructed from fossil tests and used to interpret carbon rain and intermediate water ventilation histories.; Test calcification occurs at 0–1mm for Bolivina argentea , 4–6mm for Buliminella tenuata, and 1–3mm for Bolivina subadvena. The δ13C of live B. argentea approximates pore water δ13 C at 0–1mm, B. tenuata displays the lowest δ13C, and B. subadvena displays intermediate values. A consistent δ13C relationship between species implies preferred habitats for calcification. The calcification depths implied by the δ13C values agree with the depths of maximum live abundance.