Tracing the history of submarine hydrothermal inputs and the significance of hydrothermal hafnium for the seawater budget-a combined Pb-Hf-Nd isotope approach

Publication Type  Journal Article
Year of Publication  2004
Authors  van de Flierdt, T.; Frank, M.; Halliday, A. N.; Hein, J. R.; Hattendorf, B.; Gunther, D.; Kubik, P. W.
Journal Title  Earth and Planetary Science Letters
Volume  222
Issue  1
Pages  259-273
Journal Date  May 15
ISBN Number  0012-821X
Accession Number  ISI:000221502000020
Key Words  hydrothermal fluids; hf isotopes; ph isotopes; ferromanganese crusts; galapagos rise; east pacific rise; mid-atlantic ridge; metalliferous sediments; ferromanganese crusts; hot-springs; vent field; southeastern pacific; bauer deep; lead; ocean
Abstract  

Secular variations in the Pb isotopic composition of a mixed hydrogenous-hydrothermal ferromanganese crust from the Bauer Basin in the eastern Equatorial Pacific provide clear evidence for changes in hydrothermal contributions during the past 7 Myr. The nearby Galapagos Rise spreading center provided a strong hydrothermal flux prior to 6.5 Ma. After 6.5 Ma, the Pb became stepwise more radiogenic and more similar to Equatorial Pacific seawater, reflecting the westward shift of spreading to the presently active East Pacific Rise (EPR). A second, previously unrecognized enhanced hydrothermal period occurred between 4.4 and 2.9 Ma, which reflects either off-axis hydrothermal activity in the Bauer Basin or a late-stage pulse of hydrothermal Pb from the then active, but waning Galapagos Rise spreading center.Hafnium isotope time-series of the same mixed hydrogenous-hydrothermal crust show invariant values over the past 7 Myr. Haffiium isotope ratios, as well as Nd isotope ratios obtained for this crust, are identical to that of hydrogenous Equatorial Pacific deep water crusts and clearly indicate that hydrothermal Hf, similar to Nd, does not travel far from submarine vents. Therefore, we suggest that hydrothermal Hf fluxes do not contribute significantly to the global marine Hf budget. (C) 2004 Elsevier B.V. All rights reserved.

Notes  

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URL  <Go to ISI>://000221502000020
DOI  DOI 10.1016/j.epsl.2004.02.025