Sulfate ventilation of marine sediments indicated by depth profiles of porewater sulfate and δ34S

Author(s): Claypool, George E.
Author Affiliation(s): Primary:
8910 West Second Avenue, Lakewood, CO, United States
Volume Title: Geological Society of America, 2002 annual meeting
Source: Abstracts with Programs - Geological Society of America, 34(6), p.153; Geological Society of America, 2002 annual meeting, Denver, CO, Oct. 27-30, 2002. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Anoxic marine sediments are characterized by systematic decrease in concentration of dissolved sulfate in the interstitial waters of marine sediments. This depletion in dissolved sulfate can take place over depth scales ranging from a few centimeters up to a few hundred meters. Accompanying this decrease in sulfate concentration is an increase in δ34S, which is due to preferential utilization of the 32S-isotope during bacterial sulfate reduction. The degree of 34S-enrichment for a given degree of dissolved sulfate depletion is also highly variable, and reflects the extent to which the sediment column is relatively open or closed to diffusive replenishment of sulfate during bacterial sulfate reduction. Gradients in stable sulfur isotope ratios and concentration of dissolved sulfate in porewaters of marine sediments have been compiled from about 40 sites of the Deep Sea Drilling Project and the Ocean Drilling Program, ranging from Legs 4 through 188. Linear sedimentation rate for these sites ranges from about 5 to 1500 meters per million years. The apparent 34S-enrichment factor (from Rayleigh equation) ranges from 4 to 72 per mil (α = 1.004 to 1.072), and is directly proportional to a system "openness" parameter (i.e., diffusive sulfate flux divided by the diffusive plus burial sulfate flux) which ranges from 0.06 to 0.87 for the compiled sites. Under conditions represented by DSDP/ODP cores, bacterial sulfate reduction occurs with a relatively large 34S-isotopic enrichment (75 per mil), which is diluted by variable degrees of replenishment with unfractionated seawater sulfate.
Year of Publication: 2002
Research Program: DSDP Deep Sea Drilling Project
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; Anaerobic environment; Bacteria; Deep Sea Drilling Project; Diffusion; Isotope ratios; Isotopes; Marine sediments; Ocean Drilling Program; Pore water; Reduction; S-34/S-32; Sea water; Sedimentation; Sedimentation rates; Sediments; Solutes; Stable isotopes; Sulfate ion; Sulfur; Utilization
Record ID: 2004033174
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States

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