An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific
An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific
复制标题
DOI：
10.1016/j.epsl.2020.116223
复制
发表时间：
2020-06
影响因子：
5.3
通讯作者：
W. J. Jenkins;M. Hatta;J. Fitzsimmons;R. Schlitzer;N. Lanning;Alan Shiller;N. R. Buckley;C. R. German;D. Lott;G. Weiß;L. Whitmore;K. Casciotti;Phoebe J. Lam;G. Cutter;K. Cahill
中科院分区：
文献类型：
--
作者：
W. J. Jenkins;M. Hatta;J. Fitzsimmons;R. Schlitzer;N. Lanning;Alan Shiller;N. R. Buckley;C. R. German;D. Lott;G. Weiß;L. Whitmore;K. Casciotti;Phoebe J. Lam;G. Cutter;K. Cahill
我们观察到大水柱异常氦同位素和微量金属浓度以上的Loihi海山。氦的3 He/4 He比是大气的27.3倍，这表明它的起源是一个原始地幔柱。向周围沃茨输出的溶解铁与3 He的比值（dFe：3 He）为9.3± 0.3 × 10 6。在距Loihi 100-1000 km范围内的几个测站，观测到1100 m深度的Loihi ~（3-）He和dFe“信号”，其远源dFe：~（3-）He比值为10.4 × 106，约为近源的一半。这些比率是非常相似的东南太平洋海隆（SEPR），尽管有很大的对比地球化学和火山构造的起源和附近观察到的。与此相反，近端和远端dMn：3 He比值均为0.1 × 106，不到SEPR时观察到的值的一半。溶解的甲烷最低限度地富集在沃茨以上Loihi海山和远端缺席。使用理想化的区域尺度模型，我们复制了历史上观察到的区域3 He分布，需要来自Loihi的热液3 He源为10.4±4.2 mol a-1，占全球深海热液3 He通量的0.2%。由此我们计算出相应的dFe通量为1.40 Mmol a− 1。全球环流模式模拟表明，洛希影响的沃茨最终上升沿着北美西海岸，也延伸到西北太平洋浅水区，使其成为一个可能的重要决定因素，海洋初级生产在副极地北太平洋。
We observed large water column anomalies in helium isotopes and trace metal concentrations above the Loihi Seamount. The 3 He/4 He of the added helium was 27.3 times the atmospheric ratio, clearly marking its origin to a primitive mantle plume. The dissolved iron to 3 He ratio (dFe: 3 He) exported to surrounding waters was 9.3±0.3× 10 6. We observed the Loihi 3 He and dFe “signal” at a depth of 1100 m at several stations within∼ 100–1000 km of Loihi, which exhibited a distal dFe: 3 He ratio of∼ 4× 10 6, about half the proximal ratio. These ratios were remarkably similar to those observed over and near the Southern East Pacific Rise (SEPR) despite greatly contrasting geochemical and volcanic-tectonic origins. In contrast, the proximal and distal dMn: 3 He ratios were both∼ 1× 10 6, less than half of that observed at the SEPR. Dissolved methane was minimally enriched in waters above Loihi Seamount and was distally absent. Using an idealized regional-scale model we replicated the historically observed regional 3 He distribution, requiring a hydrothermal 3 He source from Loihi of 10.4±4.2 mol a− 1,∼ 2% of the global abyssal hydrothermal 3 He flux. From this we compute a corresponding dFe flux of∼ 40 Mmol a− 1. Global circulation model simulations suggest that the Loihi-influenced waters eventually upwell along the west coast of North America, also extending into the shallow northwest Pacific, making it a possibly important determinant of marine primary production in the subpolar North Pacific.