Variations of V isotope ratios (δ⁵¹V) in sedimentary rocks have been proposed as a potential proxy for paleo-oceanic redox conditions, although the marine δ⁵¹V system is not fully constrained. Hydrothermal sediments are known to be a significant sink of V from the ocean. However, the V isotope fractionation associated with the accumulation into hydrothermal sediments from seawater and its influence on the marine isotopic budget of V are still unexplored. This work presents the first V isotope study of hydrothermal sediments specifically samples from the Trans-Atlantic Geotraverse (TAG) hydrothermal field and Pacific Ocean under influence of the hydrothermal plume arising from the southern East Pacific Rise (SEPR). The studied sediments show authigenic δ⁵¹V values ranging from −0.4 to −0.1‰, which is remarkably different from that of non-hydrothermal oxic sediments (−1.2 to −0.7‰) as well as open ocean seawater (+0.2‰). The V isotope composition of these hydrothermal sediments at TAG is likely controlled by the isotope fractionation during the rapid initial uptake of V from seawater into hydrothermal Fe oxyhydroxide particulates that precipitate when reducing hydrothermal fluids mix with oxic seawater. The sediments collected from the deep south Pacific Ocean west of SEPR show authigenic δ⁵¹V values overlapping with the range observed within the TAG field, despite their distal location extending to more than 4000 km from the buoyant portion of the SEPR hydrothermal plume. As has also been observed for Fe in particulates west of the SEPR, our results indicate the persistence of V within hydrothermal particulates (likely in the form of V-rich Fe oxyhydroxides) that settle to the sediments after long-range transport, while still preserving the original V isotope signature. Combination of this work with previous studies, allows us to establish a more robust mass balance model that assesses the effect of V removal by hydrothermal precipitation on the marine elemental and isotopic budget of V. Our new results suggest that the flux of V into the hydrothermal sink accounts for ∼13% of the global marine V input. This model also indicates that the V isotope composition of seawater could potentially be altered with variations in hydrothermal activity which is in addition to changes in the global marine redox conditions but likely on very different time scales. Thus, V isotope ratios have the potential to provide new insights into ancient ocean chemistry.

^{尽管海洋 δ 51} V 系统并未受到完全限制，但沉积岩中 V 同位素比 (δ ^{51 V) 的变化已被提议作为古海洋氧化还原条件的潜在代表。}已知热液沉积物是海洋中 V 的重要汇。然而，与从海水中积累到热液沉积物中相关的 V 同位素分馏及其对 V 的海洋同位素收支的影响仍未得到探索。这项工作提出了第一次对热液沉积物的 V 同位素研究，特别是在东太平洋海隆 (SEPR) 南部产生的热液羽流的影响下，来自跨大西洋地地穿越 (TAG) 热液场和太平洋的样品。研究的沉积物显示自生 δ ⁵¹V 值范围为-0.4 至-0.1‰，与非热液含氧沉积物（-1.2 至-0.7‰）以及公海海水（+0.2‰）显着不同。TAG 处这些热液沉积物的 V 同位素组成可能受同位素分馏的控制，在 V 从海水中快速初始吸收到热液羟基氧化铁颗粒中时，这些颗粒在还原热液流体与含氧海水混合时沉淀。从 SEPR 以西的南太平洋深海收集的沉积物显示出自生 δ ⁵¹V 值与 TAG 场内观察到的范围重叠，尽管它们的远端位置从 SEPR 热液羽流的浮力部分延伸到 4000 多公里。正如在 SEPR 以西的颗粒物中的 Fe 也观察到的那样，我们的结果表明 V 在热液颗粒中的持久性（可能以富含 V 的 Fe 羟基氧化物的形式）在远距离迁移后沉降到沉积物中，同时仍然保留原始 V 同位素特征。将这项工作与以前的研究相结合，使我们能够建立一个更稳健的质量平衡模型，以评估通过热液降水去除 V 对 V 的海洋元素和同位素预算的影响。我们的新结果表明 V 进入热液的通量sink 占全球海洋 V 输入的 13%。该模型还表明，除了全球海洋氧化还原条件的变化之外，海水的 V 同位素组成可能会随着热液活动的变化而改变，但可能在非常不同的时间尺度上发生变化。因此，V 同位素比率有可能为古代海洋化学提供新的见解。