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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Oceanographic and climatic evolution of the southeastern subtropical Atlantic over the last 3.5 Ma
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Oceanographic and climatic evolution of the southeastern subtropical Atlantic over the last 3.5 Ma

机译：在过去的3.5 ma中，东南亚热带大西洋的海洋学和气候演变

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The southeast Atlantic Ocean is dominated by two major oceanic systems: the Benguela Upwelling System, one of the world's most productive coastal upwelling cells and the Agulhas Leakage, which is important for transferring warm salty water from the Indian Ocean to the Atlantic Ocean. Here, we present a multi-proxy record of marine sediments from ODP Site 1087. We reconstruct sea surface temperatures (U-37(K') and TEX86 indices), marine primary productivity (total chlorin and alkenone mass accumulation rates), and terrestrial inputs derived from southern Africa (Ti/Al and Ca/Ti via XRF scanning) to understand the evolution of the Southeast Atlantic Ocean since the late Pliocene. In the late Pliocene and early Pleistocene, ODP Site 1087 was situated within the Benguela Upwelling System, which was displaced southwards relative to present. We recognize a series of events in the proxy records at 3.3, 3.0, 2.2, 1.5, 0.9 and 0.6 Ma, which are interpreted to reflect a combination of changes in the location of major global wind and oceanic systems and local variations in the strength and/or position of the winds, which influence nutrient availability. Although there is a temporary SST cooling observed around the initiation of Northern Hemisphere glaciation (iNHG), proxy records from ODP Site 1087 show no clear climatic transition around 2.7 Ma but instead most of the changes occur before this time. This observation is significant because it has been previously suggested that there should be a change in the location and/or strength of upwelling associated with this climate transition. Rather, the main shifts at ODP Site 1087 occur at ca. 0.9 Ma and 0.6 Ma, associated with the early mid-Pleistocene transition (EMPT), with a clear loss of the previous upwelling-dominated regime. This observation raises the possibility that reorganisation of southeast Atlantic Ocean circulation towards modern conditions was tightly linked to the EMPT, but not to earlier climate transitions. (C)
机译：本格拉上升流系统，在世界上最高效的沿海涌细胞之一，在阿古拉斯泄漏，这是从印度洋转移温盐水大西洋重要：东南大西洋是由两个主要的海洋系统为主。在这里，我们提出了海洋沉积物中的多代理记录从ODP网站1087.我们重建海洋表面温度（U-37（K'）和TEX86指标），海洋初级生产力（总酚和烯酮质量积累率），和陆地来自南部非洲（钛/铝和Ca /钛通过XRF扫描）得到的输入理解，因为晚上新世东南大西洋的演变。在晚上新世和早更新世，ODP站点1087被位于本格拉上升流系统，其向南相对于存在位移内。我们在3.3识别系列在代理记录事件的，3.0，2.2，1.5，0.9和0.6马，被解释为反映强度在全球主要的风能和海洋系统和局部变化的位置变化的组合和风，这影响营养物可用性的/或位置。虽然围绕北半球冰川（英寸汞柱）的冷却开始观察到一个临时的SST，从ODP网站1087代理记录显示，大约2.7马云没有明确的气候转变，而是在此之前的变化大多发生。因为先前已经提出，应该在的位置和/或上涌与这种气候转变关联强度的变化这种看法是显著。相反，在ODP网站1087的主要位移发生在约0.9 Ma和0.6马，与早期的中更新世转变（EMPT），与上涌为主政权的一个明确的损失有关。这个观察提出了朝向现代条件东南大西洋环流的重组紧紧地联系到EMPT，而不是早期的气候转变的可能性。 （C）

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