Stable Sr-isotope, Sr/Ca, Mg/Ca, Li/Ca and Mg/Li ratios in the scleractinian cold-water coral Lophelia pertusa
Stable Sr-isotope, Sr/Ca, Mg/Ca, Li/Ca and Mg/Li ratios in the scleractinian cold-water coral Lophelia pertusa
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DOI：
10.1016/j.chemgeo.2013.06.013
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发表时间：
2013-08-16
期刊：
影响因子：
3.9
通讯作者：
Dullo, W-Chr
中科院分区：
文献类型：
--
作者：
Raddatz, J.;Liebetrau, V.;Dullo, W-Chr
冷水石珊瑚的文石骨骼在古海洋学研究中可作为有价值的档案。研究了冷水珊瑚Lophelia pertusa的δ Sr-88/86、Sr/Ca、Mg/Ca、Li/Ca和Mg/Li比值记录中间水团性质的潜力。在这里，我们使用了来自欧洲大陆边缘沿着几个地点的样本，温度范围从6到14摄氏度不等。稳定锶同位素的测量进行了最近发展的双穗TIMS技术和我们的结果与不太精确的方法得到的结果不同。与以往研究中Sr-88/86与温度的强正相关相反，我们的研究结果表明，在石珊瑚中测得的Sr-88/86不受海水温度的控制，但反映了海水的Sr同位素组成，其偏移量为Delta（ST）-S-88/86 =-0.196ppm。珊瑚中测得的Li/Ca和Mg/Li与水温显著相关，与盐度无关。此外，Sr/Ca比值在L pertusa显示预期的负相关与温度。然而，在Sr/Ca数据的方差严重限制了古温度估计的准确性。Li/Ca和Mg/Ca比揭示了除了温度之外的其他影响，例如pH和/或生长或钙化速率。然而，相应的镁/锂比L pertusa更密切相关的温度，因为它们消除了这些次要影响。特别是，在L pertusa镁/锂比可能作为一个新的有前途的古温度代理中间水团。我们的数据集代表了迄今为止L pertusa最广泛的地球化学检查，揭示了Mg/Li的温度敏感性为0.015 mol/mmol/℃。然而，使用这种温度依赖性和5.3%（2SD）的精度，只有大于1.5摄氏度的温度变化才能以95%的置信度解决。(C)2013爱思唯尔有限公司版权所有。
The aragonitic skeletons of scleractinian cold-water corals can serve as valuable archives in paleoceanographic studies. The potential of delta Sr-88/86, Sr/Ca, Mg/Ca, Li/Ca and Mg/Li ratios of the cold-water coral Lophelia pertusa to record intermediate water mass properties has been investigated. Here we used samples from several locations along the European continental margin spanning a large temperature range from 6 to 14 degrees C. Stable strontium isotope measurements were carried out with the recently developed double spike TIMS technique and our results differ from those obtained with less precise methods. In contrast to the strong positive relationship with temperature of previous studies, our results suggest that delta Sr-88/86 measured in scleractinian cold-water corals is not controlled by seawater temperature, but reflects the Sr isotopic composition of seawater with an offset of Delta(ST)-S-88/86 = -0.196 parts per thousand.As found in previous studies, the elemental ratios Sr/Ca, Li/Ca and Mg/Li measured in corals are significantly related to water temperature and do not correlate with salinity. Moreover, Sr/Ca ratios in L pertusa display the expected inverse correlation with temperature. However, the variance in the Sr/Ca data severely limits the accuracy of paleotemperature estimates. The Li/Ca and Mg/Ca ratios reveal other influences besides temperature such as pH and/or growth or calcification rate. However, corresponding Mg/Li ratios in L pertusa are more tightly related to temperature as they remove these secondary effects. In particular, the Mg/Li ratio in L pertusa may serve as a new promising paleotemperature proxy for intermediate water masses. Our dataset represents the most extensive geochemical examination of L pertusa to date, revealing a temperature sensitivity of 0.015 mol/mmol/degrees C for Mg/Li. However, using this temperature dependence and the precision of 5.3% (2SD) only temperature variations larger than similar to 1.5 degrees C can be resolved with 95% confidence. (C) 2013 Elsevier B.V. All rights reserved.