The neodymium (Nd) isotopic composition of seawater is a valuable tool for the reconstruction of past water mass provenance and hence deep water geometry. A meaningful interpretation of Nd isotope down‐core records requires knowledge of potential variations of water mass end member characteristics. While often assumed temporally constant, recent investigations revealed glacial‐interglacial variability of the northern and southern Nd isotope end members in the Atlantic. These new constraints have a strong influence on the interpretation of the Atlantic deep water mass evolution, yet the processes responsible for the end member shifts remain uncertain. Here we combine a new compilation of Atlantic Nd isotope reconstructions of the early Holocene with the Nd‐enabled Bern3D model to quantify the recently proposed hypothesis of a northern Nd isotope end member shift during the early Holocene. We achieve the best model‐data fit with a strong increase of the Nd flux in the northern high latitudes by a factor of 3 to 4, which lowers the northern end member signature by about 1 ε‐unit. Our findings thus agree with the rationale that glacially weathered material entered the northern Northwest Atlantic after the ice sheets retreated late in the deglaciation and released substantial amounts of unradiogenic Nd as suggested previously. Further, we find that variations in the strength of the Atlantic Meridional Overturning Circulation (AMOC) cannot reproduce the observed Nd isotope excursions of the compiled data, ruling out an early Holocene AMOC “overshoot.”

中文翻译：

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全新世早期Nd通量升高对大西洋北部Nd同位素末端的影响

海水中的钕（Nd）同位素组成是重建过去水源和深水几何形状的宝贵工具。要对Nd同位素下核记录进行有意义的解释，就需要了解水质末端成员特征的潜在变化。尽管通常假定时间上是恒定的，但最近的研究表明，大西洋北部和南部Nd同位素末端成员的冰间变化。这些新的限制因素对大西洋深水物质演化的解释有很大的影响，但是导致最终成员移动的过程仍然不确定。在这里，我们将全新世早期的全新世大西洋Nd同位素重建与启用Nd的Bern3D模型相结合，以量化新近提出的全新世早期北Nd同位素末端成员位移的假说。我们获得了最佳的模型数据拟合，北高纬度地区的Nd通量大大增加了3到4倍，这使北端成员特征降低了约1ε单位。因此，我们的发现与这样的基本原理是一致的，即冰川融化的物质在冰盖退缩后退回并释放出大量非放射性Nd之后进入了西北大西洋北部，正如先前所建议的那样。此外，我们发现大西洋子午俯覆环流（AMOC）强度的变化无法重现所汇编数据的Nd同位素偏移，从而排除了全新世AMOC的早期“超调”。