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The mineralogy and the isotopic composition of sulfur in hydrothermal sulfide/sulfate deposits on the East Pacific Rise, 21 deg N latitudeThe mineralogy and isotopic composition of sulfur found in hydrothermal deposits associated with five groups of vents along the ridge axis of the East Pacific Rise near 21 deg N latitude are investigated. Solid samples of mixed sulfides and sulfates from mounds, chimneys and the surrounding sediment as well as fresh basaltic glass were examined with a portable X-ray fluorescence spectrometer and by scanning electron microscopy, X-ray diffractometry, and electron microprobe analysis. For the three vents of exit temperature close to 350 C, the chimneys are found to be rich in copper sulfides, while for those of temperatures around 300 C, zinc sulfide is found to predominate. The major sulfides found in the chimneys include wurtzite, chalcopyrite, pyrite and cubanite, with anhydrite the dominant sulfate. Significant mineralogical differences are found between active and inactive vents. The isotopic composition of sulfur in anhydrites from active vents is observed to be close to that of sea water and consistent with a derivation from sea water sulfate. The isotopic composition of sulfur in the sulfide minerals is explained in terms of precipitation from solutions with reduced sulfur derived from basalts or basaltic magmas, and sea water sulfate. Finally, the deposits are interpreted as the results of the mixing of H2S-dominated hydrothermal fluids with cold sea water near the sea floor.
Document ID
19810054170
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Styrt, M. M.
(MIT Cambridge, MA, United States)
Brackmann, A. J.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Holland, H. D.
(Harvard University Cambridge, MA, United States)
Clark, B. C.
(Martin Marietta Aerospace Denver, CO, United States)
Pisutha-Arnond, V.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Eldridge, C. S.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Ohmoto, H.
(Pennsylvania State University University Park, PA, United States)
Date Acquired
August 11, 2013
Publication Date
May 1, 1981
Publication Information
Publication: Earth and Planetary Science Letters
Volume: 53
Issue: 3, Ma
Subject Category
Oceanography
Accession Number
81A38574
Funding Number(s)
CONTRACT_GRANT: NSF EAR-78-17738
Distribution Limits
Public
Copyright
Other

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