Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system
Plio-Pleistocene glacial-interglacial productivity changes in the eastern equatorial Pacific upwelling system
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DOI：
10.1002/2015pa002899
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发表时间：
2016-03-01
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影响因子：
--
通讯作者：
Friedrich, Oliver
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作者：
Jakob, Kim A.;Wilson, Paul A.;Friedrich, Oliver
东赤道太平洋(EEP)上升流系统支撑着当今全球海洋初级生产力的10%，使其成为地球大气和海洋碳收支的重要组成部分。传统上，人们一直认为，自从北半球冰川作用(inHg，类似于2.7 Ma)加剧以来，EEP生产力的变化主要取决于信风强度控制的上升流强度。另一种假说认为，EEP的生产力主要受来自南部高纬度的营养物质通过模式水域提供的控制。在这里，我们提供了来自大洋钻探计划站点849的最新的上新世/早更新世的高分辨率新数据，该站点位于EEP上升流制度中心的赤道散度系统内。我们利用底栖生物和浮游有孔虫方解石中的碳同位素和沙粒堆积速率来研究2.65 Ma至2.4 Ma(海洋同位素阶段G1至94)之间的冰期-间冰期(G-IG)生产力波动。这一时间间隔包括MIS100、98和96，这是三个大范围冰川(类似于海底O-18中的1)，代表了inHg的顶峰。我们的结果表明，EEP中最新世/早更新世G-IG生产力的变化强烈地受到来自南大洋模式水域的营养物质供应的控制。我们的记录表明，从MIS100开始有明显的G-IG旋回，生产力水平从完全冰川条件下增加，并在冰川终止时达到顶峰。我们的结论是，在完全冰川条件下，来自南部高纬度的营养物质输送的增强，以及向冰川终止的叠加的增强的区域上升流，强烈地控制了从MIS100开始的EEP的初级生产力。
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, similar to 2.7Ma), 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 2.4Ma (marine isotope stages (MIS) G1 to 94). This interval includes MIS 100, 98, and 96, three large-amplitude glacials (similar to 1 in benthic O-18) 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.