The large-scale evolution of neodymium isotopic composition in the global modern and Holocene ocean revealed from seawater and archive data
The large-scale evolution of neodymium isotopic composition in the global modern and Holocene ocean revealed from seawater and archive data
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DOI：
10.1016/j.chemgeo.2017.03.018
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发表时间：
2017-05-10
期刊：
影响因子：
3.9
通讯作者：
Waelbroeck, Claire
中科院分区：
文献类型：
--
作者：
Tachikawa, Kazuyo;Arsouze, Thomas;Waelbroeck, Claire
钕同位素组成（Nd-143/Nd-144或epsilon（Nd））已被用作海洋水团和成岩输入的示踪剂。为了进一步评估这种示踪剂的可信度，我们更新了全球海水钕（Nd）数据库，并将其与水文参数（温度，盐度，营养盐和氧浓度），碳同位素比和溶解无机碳的放射性碳相结合。还汇编了全新世时期（<10，000年）沥滤物、有孔虫试验、深海珊瑚和鱼牙齿/碎屑的沉积物（Nd）数据。在水深>= 1500 m处，性质-性质图显示海水沉积物（Nd）与其他变量之间存在明显的相关性，表明大规模水团混合是深水沉积物（Nd）分布的主要控制因素。在>= 200 m处，盆地尺度海水T-S-Nd（Nd）图解显示了不同水团的同位素演化。海水和档案钕值进行了比较，使用属性属性图和T-S-钕（Nd）图。档案值一般同意相应的海水值，虽然他们往往是在太平洋的上限。在北大西洋北方存在正的和负的补偿。应用多元回归分析，以深（>= 1500米）海水数据，我们建立了经验方程，预测主要的，大规模的，深水Nd（钕）趋势，从水文参数。与预测值的大偏移被解释为显著的局部/区域影响的标志。大陆对海水和沉积物的影响主要集中在距大陆1000 km以内。一般来说，在大西洋和太平洋深度>= 600 m处，海水和档案epsilon（Nd）值形成逐渐的纬度趋势，这与Nd同位素有助于区分中层和深水深度的北方/南方水源水贡献的想法一致。
Neodymium isotopic compositions (Nd-143/Nd-144 or epsilon(Nd)) have been used as a tracer of water masses and lithogenic inputs to the ocean. To further evaluate the faithfulness of this tracer, we have updated a global seawater epsilon(Nd) database and combined it with hydrography parameters (temperature, salinity, nutrients and oxygen concentrations), carbon isotopic ratio and radiocarbon of dissolved inorganic carbon. Archive epsilon(Nd) data are also compiled for leachates, foraminiferal tests, deep-sea corals and fish teeth/debris from the Holocene period (< 10,000 years).At water depths >= 1500m, property-property plots show clear correlations between seawater epsilon(Nd) and the other variables, suggesting that large-scale water mass mixing is a primary control of deepwater epsilon(Nd) distribution. At >= 200m, basin-scale seawater T-S-epsilon(Nd) diagrams demonstrate the isotopic evolution of different water masses. Seawater and archive epsilon(Nd) values are compared using property-property plots and T-S-epsilon(Nd) diagrams. Archive values generally agree with corresponding seawater values although they tend to be at the upper limit in the Pacific. Both positive and negative offsets exist in the northern North Atlantic. Applying multiple regression analysis to deep (>= 1500m) seawater data, we established empirical equations that predict the main, large-scale, deepwater epsilon(Nd) trends from hydrography parameters. Large offsets from the predicted values are interpreted as a sign of significant local/regional influence. Dominant continental influence on seawater and archive epsilon(Nd) is observed mainly within 1000 km from the continents. Generally, seawater and archive epsilon(Nd) values form gradual latitudinal trend in the Atlantic and Pacific at depths >= 600m, consistent with the idea that Nd isotopes help distinguish between northern/southern sourced water contributions at intermediate and deep water depths.