Evidence for hydrothermal venting in Fe isotope compositions of the deep Pacific Ocean through time

Type Article
Date 2006-05
Language English
Author(s) Chu Nan-Chin1, Johnson C2, Beard B2, German C1, Nesbitt R1, Frank M3, Bohn Marcel4, 5, Kubik P6, Usui A7, Graham I8
Affiliation(s) 1 : Natl Oceanog Ctr, Southampton SO14 3ZH, Hants, England.
2 : Univ Wisconsin, Dept Geol & Geophys, Madison, WI 53706 USA.
3 : ETH, Dept Earth Sci, Inst Isotope Geol & Mineral Resources, CH-8092 Zurich, Switzerland.
4 : IFREMER, Microsonde Ouest, F-29280 Plouzane, France.
5 : CNRS, Ctr Brest, F-29280 Plouzane, France.
6 : ETH Honggerberg, Paul Scherrer Inst, Inst Particle Phys, CH-8093 Zurich, Switzerland.
7 : Kochi Univ, Dept Earth Hist & Environm Sci, Kochi, Japan.
8 : Inst Geol & Nucl Sci, Wellington, New Zealand.
Source Earth and Planetary Science Letters (0012-821X) (Elsevier), 2006-05 , Vol. 245 , N. 1-2 , P. 202-217
DOI 10.1016/j.epsl.2006.02.043
WOS© Times Cited 47
Keyword(s) Pacific Ocean, Izu Bonin, Hydrothen nal, Ferromanganese crusts, Fe isotopes
Abstract Temporal variations in Fe isotope compositions at three locations in the Pacific Ocean over the last 10 Ma are inferred from high-resolution analyses of three hydrogenetic ferromanganese crusts. Iron pathways to the central deep Pacific Ocean appear to have remained constant over the past 10 Ma, reflected by a remarkably constant Fe isotope composition, despite large changes in the Fe delivery rates to the surface ocean via dust. These results suggest that the Fe cycle in the deep ocean is decoupled from that in surface waters. By contrast, one ferromanganese crust from the Izu-Bonin (IB) back-arc/marginal basin of the W. Pacific exhibits large delta Fe-56 variations. In that crust, decreases in delta Fe-56 values correlate with increases in Mn, Mg, Ni, Cu, Zn, Me, and V contents, and consistent with periods of intense hydrothermal input and increased growth rates. A second crust located within 100 km of the first IB sample does not record any of these periods of enhanced hydrothermal input. This probably reflects the isolated pathways by which hydrothermally sourced Fe may have migrated in the back arc, highlighting the high degree of provinciality that Fe isotopes may have in the modem (oxic) oceans. Our results demonstrate that despite efficient removal at the source, hydrothermal Fe injected into the deep ocean could account for a significant fraction of the dissolved Fe pool in the deep ocean, and that hydrothermally sourced Fe fluxes to the open ocean may have lower delta(56) Fe values than those measured so far in situ at hydrothermal vents. Correlation between 656 Fe values and elements enriched in hydrothermal fluids may provide a means for distinguishing hydrothermal Fe from other low-delta Fe-56 sources to the oceans such as dissolved riverine Fe or porewaters in continental shelf sediments. (c) 2006 Elsevier B.V. All rights reserved.
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Chu Nan-Chin, Johnson C, Beard B, German C, Nesbitt R, Frank M, Bohn Marcel, Kubik P, Usui A, Graham I (2006). Evidence for hydrothermal venting in Fe isotope compositions of the deep Pacific Ocean through time. Earth and Planetary Science Letters, 245(1-2), 202-217. Publisher's official version : https://doi.org/10.1016/j.epsl.2006.02.043 , Open Access version : https://archimer.ifremer.fr/doc/00000/3700/