The geochemistry of sulfur in a 1. 3 km section of hydrothermally altered oceanic crust, DSDP Hole 504B

Journal Article · Mon May 01 00:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90206-8· OSTI ID:5097704

Alt, J C ^[1]; Anderson, T F; Bonnell, L ^[2]

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1. Washington Univ., St. Louis, MO (USA)
2. Univ. of Illinois, Urbana (USA)

DSDP Hole 504B is the only hole in oceanic crust to penetrate through the volcanic section and into hydrothermally altered sheeted dikes. The authors have carried out petrologic and sulfur isotopic analyses of sulfide and sulfate minerals and whole rocks from the core in order to place constraints on the geochemistry of sulfur during hydrothermal alteration of ocean crust. The nearly 600 m-thick pillow section has lost sulfur to seawater and has net {delta}{sup 34}S = {minus}1.8{per thousand} due to degassing of SO{sub 2} during crystallization and subsequent low temperature interaction with seawater. Hydrothermally altered rocks in the 200 m-thick transition zone are enriched in S and {sup 34}S, whereas the more than 500 m of sheeted dikes contain 720 ppm S with {delta}{sup 34}S = +0.6 {plus minus} 1.4{per thousand}. Seawater sulfate was probably reduced through oxidation of ferrous iron in hydrothermal fluids and in the transition zone rocks. Alteration of the upper crust resulted in loss of basaltic sulfur to seawater, fixation of minor seawater sulfur in the crust and redistribution of magmatic sulfur within the crust. This caused net increases in sulfur content and {delta}{sup 34}S of the upper 1.8 km of the oceanic crust.

• OSTI ID: 5097704
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 53:5; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
OCEANIC CRUST
VOLCANIC ROCKS
CHEMICAL COMPOSITION
DEGASSING
HYDROTHERMAL ALTERATION
PETROLOGY
CRYSTALLIZATION
DRILL CORES
GEOCHEMISTRY
GEOTHERMAL FLUIDS
SEAWATER
SULFUR COMPOUNDS
SULFUR CONTENT
SULFUR ISOTOPES
CHEMISTRY
EARTH CRUST
FLUIDS
GEOLOGY
HYDROGEN COMPOUNDS
IGNEOUS ROCKS
ISOTOPES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
ROCKS
WATER
580000* - Geosciences