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Evolution of the oligotrophic West Pacific Warm Pool during the Pliocene
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  • Himanshu Bali,
  • Anil K Gupta,
  • Kuppusamy Mohan,
  • Kaustubh Thirumalai,
  • Sameer K Tiwari,
  • Mruganka K Panigrahi
Himanshu Bali
IIT Kharagpur
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Anil K Gupta
Indian Institute of Technology, Kharagpur

Corresponding Author:[email protected]

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Kuppusamy Mohan
VIT University Chennai Campus
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Kaustubh Thirumalai
University of Arizona
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Sameer K Tiwari
Wadia Institute of Himalayan Geology
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Mruganka K Panigrahi
Indian Institute of Technology Kharagpur
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This study investigates the timing of development of the oligotrophic conditions and thickening of the West Pacific Warm Pool (WPWP) during the Pliocene. It has been hypothesized that the evolution of the WPWP and the establishment of equatorial Pacific zonal gradients are closely related to the narrowing of the Indonesian seaway (IS) as well as the closure of the Panama gateway; however, the timing of these events remain debated. Here we analysed planktic foraminiferal abundances combined with stable oxygen and carbon isotope ratios since the Pliocene at ODP Hole 807A, western Pacific and DSDP Site 214, eastern Indian Ocean. A comparison of the population of mixed-layer species (MLS) from both study sites shows a significant increase between ~3.15 and 1.6 Ma. On the contrary, shows a decrease in its population during this time, indicating oligotrophic conditions in the western tropical Pacific. The dC ratio of epibenthic foraminiferal species shows a decreasing trend from ~3.15 to ~2.0 Ma, indicating the lowering of productivity during this interval. Our data suggest that the WPWP developed ~3.15 Ma and was closely linked to the gradual closure of the IS.