Deigert, David; Borowski, Walter S. (2007): Sulfur geochemistry and diagenesis in a gas hydrate terrane, Cascadia Margin, offshore Oregon; role of anaerobic methane oxidation. Geological Society of America (GSA), Boulder, CO, United States, In: Anonymous, Geological Society of America, Southeastern Section, 56th annual meeting, 39 (2), 34, georefid:2008-062812

We present sulfide mineral data from south Hydrate Ridge located in a gas hydrate terrane, offshore Oregon. Sulfide sulfur concentration and the isotopic composition of sulfur (delta (super 34) S) in authigenic sulfide minerals are analyzed from sediment samples collected on Ocean Drilling Project (ODP) Leg 204. Shallow sediment samples (<25 mbsf) assess the relative importance of anaerobic methane oxidation (AMO) as a biogeochemical process, both here and at the Blake Ridge, another well known gas hydrate terrane offshore southeastern United States. Deep samples (>25 mbsf) are used to evaluate sulfur diagenesis and its controls from early Pleistocene to the present. AMO, a microbially-mediated, sulfate-depleting process, creates an environment conducive to interstitial, authigenic sulfide mineral formation. When AMO is an important process, sulfide minerals are likely to be focused near the sulfate-methane interface (SMI) and become more enriched in heavy sulfur ( (super 34) S). Preliminary data from two of three shallow sites show high authigenic sulfide sulfur levels (0.27 and 0.7 weight percent sulfur) immediately above the SMI compared to lower concentrations (0.12 and 0.41 weight percent sulfur) just below the SMI. The remaining site has no discernable pattern to the vertical distribution of sulfide sulfur concentration, but shows peak amounts of 0.52 weight percent sulfur above the SMI. Based on results from other sites in the region, we hypothesize that peak amounts of sulfide sulfur are likely precipitated due to production via AMO, but that that sulfate reduction of sedimentary organic matter is also responsible for sulfide mineralization within the sediments. The identification and timing of heavy sulfur enrichments ( (super 34) S) in deep samples may have implications to the recognition of past gas hydrate occurrences and identify periods of significant methane transport.
West: -125.1200 East: -125.0200 North: 44.3500 South: 44.3000
West: NaN East: NaN North: NaN South: NaN
Expedition: 204
Data access:
Provider: SEDIS Publication Catalogue
Data set link: (c.f. for more detailed metadata)
This metadata in ISO19139 XML format