Trace element variations in fossil corals from Tahiti collected by IODP Expedition 310: Reconstruction of marine environments during the last deglaciation (15 to 9 ka)
Trace element variations in fossil corals from Tahiti collected by IODP Expedition 310: Reconstruction of marine environments during the last deglaciation (15 to 9 ka)
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DOI：
10.1016/j.margeo.2010.02.016
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发表时间：
2010-06-15
期刊：
影响因子：
2.9
通讯作者：
Iryu, Yasufumi
中科院分区：
文献类型：
--
作者：
Inoue, Mayuri;Yokoyama, Yusuke;Iryu, Yasufumi
最近一次冰川消融期间的气候反应和海洋环境变化一直存在争议，热带南太平洋的古海洋学数据也很少，尽管这一区域在研究海-气相互作用方面至关重要。为确定南太平洋塔希提岛冰期后海平面上升的时间进程，进行了综合大洋钻探计划310次。这次考察的一个主要目的是研究最后一次冰川消融期间海洋环境的变化。由于化石波利茨珊瑚是评估过去海洋环境的理想选择，我们从许多珊瑚标本中只选择了波利茨珊瑚标本，用X射线衍射仪对它们进行了检查，并用C-14方法测定了它们的年代。我们总共获得了17个原始的孔石标本，仅由文石组成，年龄从15~9ka。在此基础上，分别测定了镁/钙、钡/钙、铀/钙比值和Cd含量作为上升流和海温的代用指标。在12.6~9.8卡的珊瑚样品中，与15卡左右的珊瑚样品相比，较高的Ba/Ca比和Cd含量以及较低的U/Ca比重建的SST表明，在此期间，塔希提岛周围的地下水上升和/或夹带到混合层中的作用增强了。这一发现与以前的报告一致，并支持南太平洋至少在12.6到9.8卡尔卡之间具有类似拉尼娜现象的特征的观点。(C)2010爱思唯尔B.V.保留所有权利。
Climate responses and changes in marine environments during the last deglaciation have been controversial and few paleoceanographic data are available from the tropical South Pacific, though this region is crucial in the investigations of ocean-atmosphere interactions. Integrated Ocean Drilling Program Expedition 310 was conducted to establish the time course of the postglacial sea-level rise at Tahiti in the South Pacific. A principal objective of this expedition was to examine the variation of marine environments during the last deglaciation. As fossil Porites coral is ideal for assessing past marine environments, we selected only Porites specimens from the many coral specimens retrieved, examined them by XRD, and dated them by the C-14 method. In all, we obtained 17 pristine Porites specimens composed of only aragonite with ages from 15 to 9 ka. Then, we measured Mg/Ca, Ba/Ca, and U/Ca ratios and Cd contents as proxies for upwelling and sea surface temperature. Higher Ba/Ca ratios and Cd content together with lower reconstructed SSTs using U/Ca ratios in the coral specimens between 12.6 and 9.8 cal ka compared to around 15 cal ka suggest that upwelling and/or entrainment of subsurface water into mixed layer was enhanced around Tahiti during this period. This finding is consistent with previous reports and supports the idea that the South Pacific was characterized by La Nina-like conditions at least from 12.6 to 9.8 cal ka. (C) 2010 Elsevier B.V. All rights reserved.