Oxygen and carbon isotopic variation in Pliocene benthic foraminifers of the equatorial Atlantic

Large changes in benthic foraminiferal δ¹⁸O and δ¹³C occurred during the Pliocene (between 3.0 and 2.0 Ma) at Hole 665A. Oxygen isotopic compositions increased to maximum values at 2.4 Ma. Benthic foraminiferal δ¹³C values are much lower at Hole 665A than at Hole 552A, approaching the low values observed in the Pliocene Pacific Ocean. This geographic distribution of δ¹³C suggests that the equatorial Atlantic Ocean was dominated during the Pliocene by deep water that originated in the Southern Ocean and had chemical characteristics very similar to the Pacific Ocean. Reduced O₂ values were probably associated with low δ¹³C values and contributed to increased preservation of organic carbon during enriched ¹⁸O intervals of the Pliocene equatorial Atlantic. -from Authors