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Atmosphere-ocean linkages in the eastern equatorial Pacific over the early Pleistocene

机译：早更新世早期赤道东太平洋的大气-海洋联系

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摘要

Here we present a new set of high-resolution early Pleistocene records from the eastern equatorial Pacific (EEP). Sediment composition from Ocean Drilling Program Sites 1240 and 1238 is used to reconstruct past changes in the atmosphere-ocean system. Particularly remarkable is the presence of laminated diatom oozes (LDOs) during glacial periods between 1.85 and 2.25Ma coinciding with high fluxes of opal and total organic carbon. Relatively low lithic particles (coarse and poorly sorted) and iron fluxes during these glacial periods indicate that the increased diatom productivity did not result from dust-stimulated fertilization events. We argue that glacial fertilization occurred through the advection of nutrient-rich waters from the Southern Ocean. In contrast, glacial periods after 1.85Ma are characterized by enhanced dust transport of finer lithic particles acting as a new source of nutrients in the EEP. The benthic ecosystem shows dissimilar responses to the high productivity recorded during glacial periods before and after 1.85Ma, which suggests that the transport processes delivering organic matter to the deep sea also changed. Different depositional processes are interpreted to be the result of two distinct glacial positions of the Intertropical Convergence Zone (ITCZ). Before 1.85Ma, the ITCZ was above the equator, with weak local winds and enhanced wet deposition of dust. After 1.85Ma, the glacial ITCZ was displaced northward, thus bringing stronger winds and stimulating upwelling in the EEP. The glacial period at 1.65Ma with the most intense LDOs supports a rapid southward migration of the ITCZ comparable to those glacial periods before 1.85Ma.
机译：在这里，我们介绍了来自赤道东太平洋（EEP）的一组新的高分辨率早期更新世记录。海洋钻探计划站点1240和1238的沉积物成分用于重建过去的大气-海洋系统变化。特别令人瞩目的是在1.85Ma和2.25Ma之间的冰川期存在叠层硅藻泥（LDO），这与蛋白石和总有机碳的高通量相吻合。在这些冰川期，相对较低的岩屑颗粒（粗粒和分类不良）和铁通量表明，硅藻产量的提高并不是由受粉尘刺激的施肥事件引起的。我们认为冰川受精是通过对流来自南大洋的营养丰富的水而发生的。相比之下，在1.85Ma之后的冰川期的特征是，作为EEP中新的养分来源的较细的石屑颗粒的尘埃输送增强。底栖生态系统对在1.85Ma前后的冰川期记录的高生产力表现出不同的响应，这表明向深海输送有机质的运输过程也发生了变化。不同的沉积过程被解释为是热带辐合带（ITCZ）两个不同冰川位置的结果。在1.85Ma之前，ITCZ位于赤道上方，局部风弱，灰尘的湿沉降增加。在1.85Ma之后，冰川ITCZ向北移动，从而带来更强的风，并激发了EEP的上升流。与1.85Ma之前的冰川期相比，LDO最强的1.65Ma冰川期支持ITCZ的快速南移。

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