Pliocene-Pleistocene variability of upwelling activity, productivity, and nutrient cycling in the Benguela region
Pliocene-Pleistocene variability of upwelling activity, productivity, and nutrient cycling in the Benguela region
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DOI：
10.1130/g25733a.1
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发表时间：
2009-10-01
期刊：
影响因子：
5.8
通讯作者：
Schneider, Ralph
中科院分区：
文献类型：
--
作者：
Etourneau, Johan;Martinez, Philippe;Schneider, Ralph
在这项研究中，我们提供了过去3.5 Ma本格拉上升流系统(BUS)海表面温度(SST)、浮游植物生产力和营养物质循环的高分辨率组合记录。海温记录提供的证据表明，由于南大洋的冷却和由此导致的信风的加强，纳米比亚近海的上升流活动主要在2.4-2.0 Ma前增强。正如与生产力相关的指标所揭示的那样，当考虑终止Matuyama硅藻高峰期(硅藻高产事件)时，公共汽车集约化导致了区域生物生产力的重大转变。本格拉的主要海洋重组伴随着营养源的变化，正如一项新的氮同位素(增量N-15)记录所表明的那样，该记录显示在约2.4 Ma和约1.5 Ma前逐步增加。源区的变化可能是由于与南大洋海洋条件重组有关的中间水形成的显著变化，而南大洋可能反过来主要控制了全球海洋N循环，从而控制了3.5 Ma以来营养物质的N同位素组成。
In this study we present combined high-resolution records of sea surface temperature (SST), phytoplankton productivity, and nutrient cycling in the Benguela Upwelling System (BUS) for the past 3.5 Ma. The SST record provided evidence that upwelling activity off Namibia mainly intensified ca.2.4-2.0 Ma ago in response to the cooling of the Southern Ocean and the resultant strengthening of trade winds. As revealed by productivity-related proxies, BUS intensification led to a major transition in regional biological productivity when considering the termination of the Matuyama Diatom Maximum (a diatom high-production event). Major oceanic reorganization in the Benguela was accompanied by nutrient source changes, as indicated by a new nitrogen isotopic (delta N-15) record that revealed a stepwise increase at ca. 2.4 and ca. 1.5 Ma ago. The change in source region likely resulted from significant changes in intermediate water formation tied to the reorganization of oceanic conditions in the Southern Ocean, which may have in turn mainly controlled the global ocean N cycle, and therefore the N isotopic composition of nutrients since 3.5 Ma ago.