The effect of plume processes on the Fe isotope composition of hydrothermally derived Fe in the deep ocean as inferred from the Rainbow vent site, Mid-Atlantic Ridge, 36°14′N
The effect of plume processes on the Fe isotope composition of hydrothermally derived Fe in the deep ocean as inferred from the Rainbow vent site, Mid-Atlantic Ridge, 36°14′N
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DOI：
10.1016/j.epsl.2004.06.001
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发表时间：
2004-08
影响因子：
5.3
通讯作者：
S. Severmann;C. Johnson;B. Beard;C. German;H. Edmonds;H. Chiba;D. Green
中科院分区：
文献类型：
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作者：
S. Severmann;C. Johnson;B. Beard;C. German;H. Edmonds;H. Chiba;D. Green
Rainbow热液喷口是已知最大的向北大西洋深海输送溶解铁的点源，根据对羽流下含金属沉积物的分析，其铁同位素组成至少在过去16 000年中保持不变。由于铁在彩虹羽流中的保守行为，中性浮力羽流中颗粒的δ 56 Fe值（−0.18±0.05‰）和下伏沉积物（−0.19±0.05‰）与高温流体源的δ 56 Fe值（−0.23±0.04‰）无法区分。然而，来自近喷口、羽流浮力阶段的颗粒相对于原始喷口流体具有更高的δ 56 Fe值（+0.15‰至+1.20‰），这与Fe（II）aq氧化为Fe（III）aq过程中的分馏相一致。一旦所有的Fe（II）aqis完全氧化，同位素组合物成为不变的羽流，保持原始的组成的喷口流体。恒定的Fe同位素组成的喷口流体随着时间的推移意味着，在北大西洋的海水Fe同位素组成的变化，因为它们是记录在铁锰结壳，需要在Fe的相对通量的变化到海洋。
The Rainbow hydrothermal vent site, which is the largest known point source for dissolved Fe delivered to the deep North Atlantic ocean, has remained invariant in its Fe isotope composition over at least the past 16,000 years, based on analysis of metalliferous sediments beneath the plume. Because of the conservative behavior of Fe in the Rainbow plume, δ56Fe values of particles in the neutrally buoyant plume (−0.18±0.05‰) and underlying sediments (−0.19±0.05‰) are indistinguishable from the δ56Fe values of the high-temperature fluid sources (−0.23±0.04‰). Particles from the near-vent, buoyant stage of the plume, however, have higher δ56Fe values (+0.15‰ to +1.20‰) relative to the original vent fluid, consistent with fractionation during oxidation of Fe(II)aqto Fe(III)aq. Isotope compositions become invariant in the plume once all Fe(II)aqis fully oxidized, preserving the original composition of the vent fluid. The constant Fe isotope compositions of the vent fluids over time implies that changes in seawater Fe isotope composition of the North Atlantic ocean, as they are recorded in Fe–Mn crusts, requires changes in the relative fluxes of Fe to the ocean.