Bottoms up: Sedimentary control of the deep North Pacific Ocean's εNd signature
Bottoms up: Sedimentary control of the deep North Pacific Ocean's εNd signature
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DOI：
10.1130/g37114.1
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发表时间：
2015-11-01
期刊：
影响因子：
5.8
通讯作者：
McManus, James
中科院分区：
文献类型：
--
作者：
Abbott, April N.;Haley, Brian A.;McManus, James
重建过去洋流的能力对于确定海洋环流在全球热输送和气候变化中的作用至关重要。我们对过去环流和气候之间关系的理解使我们能够预测未来气候驱动的环流变化的影响。过去海洋环流的一种被提出的示踪剂是古代水团的钕同位素组成（epsilon(Nd)）。然而，在现代海洋中支配ε (Nd)分布的不明确因素阻碍了对这种示踪剂的解释。在这里，我们给出了北太平洋三个地点的海洋孔隙流体、沉积物和上覆水柱的epsilon（Nd）值。研究发现，东北太平洋海底水epsilon(Nd) （epsilon(NdBW)）介于水体质量期望值（-3.3）和沉积物孔隙流体测量值（epsilon(NdPW)）之间；-1.8)。此外，epsilon（NdPW）与沉积物的epsilon（Nd）相似。综上所述，这些发现与最近的评估结果一致，即沉积物孔隙流体可能是海洋稀土元素的主要来源，并表明来自孔隙流体的底生物Nd通量对epsilon（Nd）的深海分布起主要控制作用。
The ability to reconstruct past ocean currents is essential for determining ocean circulation's role in global heat transport and climate change. Our understanding of the relationship between circulation and climate in the past allows us to predict the impact of future climate-driven circulation changes. One proposed tracer of past ocean circulation is the neodymium isotope composition (epsilon(Nd)) of ancient water masses. However, ambiguities in what governs the epsilon(Nd) distribution in the modern ocean hamper interpretations of this tracer. Here we present epsilon(Nd) values for marine pore fluids, sediments, and the overlying water column for three sites in the North Pacific. We find that ocean bottom water epsilon(Nd) (epsilon(NdBW)) in the northeast Pacific lies between the value expected for the water mass (-3.3) and the measured epsilon(Nd) of sediment pore fluid (epsilon(NdPW); -1.8). Moreover, epsilon(NdPW) resembles the epsilon(Nd) of the sediment. Combined, these findings are consistent with recent assessments that sediment pore fluids may be a major source of rare earth elements to the ocean and suggest that the benthic flux of Nd from pore fluids exerts the primary control over the deep ocean distribution of epsilon(Nd).