Precession forcing of productivity in the Eastern Equatorial Pacific during the last glacial cycle
Precession forcing of productivity in the Eastern Equatorial Pacific during the last glacial cycle
复制标题
DOI：
10.1016/j.quascirev.2012.02.020
复制
发表时间：
2012-04
影响因子：
4
通讯作者：
E. Ivanova;L. Beaufort;L. Vidal;M. Kučera
中科院分区：
文献类型：
--
作者：
E. Ivanova;L. Beaufort;L. Vidal;M. Kučera
我们介绍了一种新的多代理重建的海面属性，跨越了过去140千卡的图像核心MD02-2529位于哥斯达黎加附近的热带太平洋东部。对记录的光谱分析使我们能够检查浮游有孔虫和球虫组合的轨道变化的生态印记，以及赤道上升流以北的赤道东太平洋初级生产的模式。基于浮游植物和浮游动物组合的独立生产力重建显示出以轨道进动为主的一致模式，这似乎具有在上一个冰川-间冰期周期中在所研究的岩心记录的控制生产力变化。提出的这种控制机制调用了与春季和秋季赤道太阳辐射极大值有关的大气强迫，周期为∼20ka。更强的上层海洋混合和对真光层的营养供应增加的动物群证据表明，当地大气环流更加活跃，哥斯达黎加穹顶相应扩大，在5月日晒最大时影响了核心地点。研究记录中的最后两次终止与浮游生物组合的明显变化有关，这需要额外的营养物质输送机制来放大进动强迫。我们的动物群和稳定的同位素数据支持在冰川消融期间通过南大洋的营养物质平流进行的隧道作业。
We present a new multi-proxy reconstruction of sea-surface properties spanning the last 140 ka in the IMAGES Core MD02-2529 located in the eastern tropical Pacific Ocean off Costa Rica. Spectral analysis of the records allowed us to examine the ecological imprints of orbital changes on planktic foraminiferal and coccolithophore assemblages and on the pattern of primary production in the Eastern Equatorial Pacific, north of the Equatorial upwelling. Independent productivity reconstructions based on phyto- and zooplankton assemblages show a coherent pattern dominated by orbital precession, which appears to have control productivity changes recorded in the studied core over the last glacial–interglacial cycle. The proposed mechanism of this control invokes an atmospheric forcing associated with equatorial insolation maxima in spring and fall with a period of ∼20 ka. Faunal evidence for a stronger upper-ocean mixing with enhanced nutrient supply to the euphotic zone suggests a more vigorous local atmospheric circulation and associated enlargement of the Costa Rica Dome that influenced the core site at times of May insolation maxima. The last two terminations in the studied record are associated with conspicuous changes in planktic assemblages which require additional nutrient-delivery mechanisms to amplify the precession forcing. Our faunal and stable isotope data are in favour of the previously postulated nutrient advection via the Southern Ocean “tunnelling” operating during deglaciations.