TY - JOUR
T1 - 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
AU - Severmann, S.
AU - Johnson, C. M.
AU - Beard, B. L.
AU - German, C. R.
AU - Edmonds, H. N.
AU - Chiba, H.
AU - Green, D. R.H.
N1 - Funding Information:
This work was supported by NASA-Ames (JRI NCC 2-5449) and the NSF (EAR-0106614). Sampling for this work was funded through EC contract MAST3-CT95-00, the NERC's BRIDGE project (UK) and InterRidge Japan. We thank the crew of the R/V Yokosuka and DSV Shinkai 6500 team for assistance during cruise MODE '98 Leg 2. Underpinning research was enabled by NERC Core Strategic Science funding at SOC (CRG & DRHG) and a NATO post-doctoral research fellowship (HNE). We thank Allan Matthews and an anonymous reviewer, as well as the Associate Editor Ed Boyle for constructive comments.
PY - 2004/8/30
Y1 - 2004/8/30
N2 - 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, δ 56Fe values of particles in the neutrally buoyant plume (-0.18±0.05‰) and underlying sediments (-0.19±0.05‰) are indistinguishable from the δ 56Fe values of the high-temperature fluid sources (-0.23±0.04‰). Particles from the near-vent, buoyant stage of the plume, however, have higher δ 56Fe values (+0.15‰ to +1.20‰) relative to the original vent fluid, consistent with fractionation during oxidation of Fe(II)aq to Fe(III)aq. Isotope compositions become invariant in the plume once all Fe(II)aq is 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.
AB - 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, δ 56Fe values of particles in the neutrally buoyant plume (-0.18±0.05‰) and underlying sediments (-0.19±0.05‰) are indistinguishable from the δ 56Fe values of the high-temperature fluid sources (-0.23±0.04‰). Particles from the near-vent, buoyant stage of the plume, however, have higher δ 56Fe values (+0.15‰ to +1.20‰) relative to the original vent fluid, consistent with fractionation during oxidation of Fe(II)aq to Fe(III)aq. Isotope compositions become invariant in the plume once all Fe(II)aq is 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.
KW - Fe isotopes
KW - Hydrothermal plumes
KW - Metalliferous sediments
KW - Rainbow vent site
KW - Seawater isotope composition
UR - http://www.scopus.com/inward/record.url?scp=4344686139&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=4344686139&partnerID=8YFLogxK
U2 - 10.1016/j.epsl.2004.06.001
DO - 10.1016/j.epsl.2004.06.001
M3 - Article
AN - SCOPUS:4344686139
SN - 0012-821X
VL - 225
SP - 63
EP - 76
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 1-2
ER -