Pliocene evolution of the tropical Atlantic thermocline depth

Abstract. It has been hypothesized that global temperature trends are tightly linked to tropical thermocline depth, and shoaling played a crucial role in the intensification of late Pliocene Northern Hemisphere glaciation. The evolution Pacific Ocean is well documented supports this hypothesis, but records from Atlantic limited. We present new planktonic foraminiferal Mg/Ca, δ18O, δ13C interval at Drilling Program Site 959 Eastern Equatorial (EEA), which we use reconstruct ocean temperatures relative changes salinity depth. Data were generated using surface-dwelling Globigerinoides ruber subsurface-dwelling Neogloboquadrina dutertrei. Reduced gradients between surface subsurface indicate deepening EEA end mid-Piacenzian Warm Period (mPWP; ∼ 3.3–3.0 Ma). connect our previously published early δ18O data compare these 1000 Caribbean Sea. Over course Pliocene, Sea follow similar patterns, with prominent step-wise 5.5 4.0 Ma gradual up mPWP, followed by minor mPWP. depth differs Pacific, characterized basin-wide across Pliocene. These results potentially challenge link climate. mechanisms behind periodically divergent movements remain speculative. suggest they related basin geometry heterogenous evolutions regions where waters sourced. A positive feedback loop source region cyclone activity may have amplified adjustments.