Open AccessPlio‐Pleistocene glacial‐interglacial productivity changes in the eastern equatorial Pacific upwelling system
Author(s) -
Jakob Kim A.,
Wilson Paul A.,
Bahr André,
Bolton Clara T.,
Pross Jörg,
Fiebig Jens,
Friedrich Oliver
Publication year - 2016
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1002/2015pa002899
Subject(s) - glacial period , upwelling , interglacial , geology , oceanography , marine isotope stage , productivity , pleistocene , benthic zone , stadial , paleontology , economics , macroeconomics
Abstract The eastern equatorial Pacific Ocean (EEP) upwelling system supports >10% of the present‐day global ocean primary production, making it an important component in Earth's atmospheric and marine carbon budget. Traditionally, it has been argued that since intensification of Northern Hemisphere glaciation (iNHG, ~2.7 Ma), changes in EEP productivity have predominantly depended on trade wind strength‐controlled upwelling intensity. An alternative hypothesis suggests that EEP productivity is primarily controlled by nutrient supply from the high southern latitudes via mode waters. Here we present new high‐resolution data for the latest Pliocene/early Pleistocene from Ocean Drilling Program Site 849, located within the equatorial divergence system in the heart of the EEP upwelling regime. We use carbon isotopes in benthic and planktic foraminiferal calcite and sand accumulation rates to investigate glacial‐interglacial (G‐IG) productivity fluctuations between 2.65 and 2.4 Ma (marine isotope stages (MIS) G1 to 94). This interval includes MIS 100, 98, and 96, three large‐amplitude glacials (~1‰ in benthic δ 18 O) representing the culmination of iNHG. Our results suggest that latest Pliocene/early Pleistocene G‐IG productivity changes in the EEP were strongly controlled by nutrient supply from Southern Ocean‐sourced mode waters. Our records show a clear G‐IG cyclicity from MIS 100 onward with productivity levels increasing from full glacial conditions and peaking at glacial terminations. We conclude that enhanced nutrient delivery from high southern latitudes during full glacial conditions together with superimposed intensified regional upwelling toward glacial terminations strongly regulated primary productivity rates in the EEP from MIS 100 onward.