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Alt, Jeffrey C; Shanks, Wayne C; Paulick, Holger; Garrido, Carlos J; Beaudoin, Georges (2007): Oxygen and sulfur isotopes of peridotite and gabbro from the Mid-Atlantic Ridge. PANGAEA, https://doi.org/10.1594/PANGAEA.734345, Supplement to: Alt, JC et al. (2007): Hydrothermal alteration and microbial sulfate reduction in peridotite and gabbro exposed by detachment faulting at the Mid-Atlantic Ridge, 15°20'N (ODP Leg 209): A sulfur and oxygen isotope study. Geochemistry, Geophysics, Geosystems, 8(8), 1-22, https://doi.org/10.1029/2007GC001617

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Abstract:
Whole rock sulfur and oxygen isotope compositions of altered peridotites and gabbros from near the 15°20'N Fracture Zone on the Mid-Atlantic Ridge were analyzed to investigate hydrothermal alteration processes and test for a subsurface biosphere in oceanic basement. Three processes are identified. (1) High-temperature hydrothermal alteration (~250-350°C) at Sites 1268 and 1271 is characterized by 18O depletion (2.6-4.4 per mil), elevated sulfide-S, and high delta34S (up to ~2 wt% and 4.4-10.8 per mil). Fluids were derived from high-temperature (>350°C) reaction of seawater with gabbro at depth. These cores contain gabbroic rocks, suggesting that associated heat may influence serpentinization. (2) Low-temperature (<150°C) serpentinization at Sites 1272 and 1274 is characterized by elevated delta18O (up to 8.1 per mil), high sulfide-S (up to ~3000 ppm), and negative delta34S (to -32.1 per mil) that reflect microbial reduction of seawater sulfate. These holes penetrate faults at depth, suggesting links between faulting and temperatures of serpentinization. (3) Late low-temperature oxidation of sulfide minerals caused loss of sulfur from rocks close to the seafloor. Sulfate at all sites contains a component of oxidized sulfide minerals. Low delta34S of sulfate may result from kinetic isotope fractionation during oxidation or may indicate readily oxidized low-delta34S sulfide derived from microbial sulfate reduction. Results show that peridotite alteration may be commonly affected by fluids +/- heat derived from mafic intrusions and that microbial sulfate reduction is widespread in mantle exposed at the seafloor.
Project(s):
Coverage:
Median Latitude: 15.083251 * Median Longitude: -45.377656 * South-bound Latitude: 14.721080 * West-bound Longitude: -46.903610 * North-bound Latitude: 15.741430 * East-bound Longitude: -44.884730
Date/Time Start: 2003-03-23T16:45:00 * Date/Time End: 2003-07-01T13:00:00
Event(s):
209-1268A * Latitude: 14.845910 * Longitude: -45.077350 * Date/Time Start: 2003-05-22T05:45:00 * Date/Time End: 2003-05-26T19:30:00 * Elevation: -3007.0 m * Penetration: 147.6 m * Recovery: 78.69 m * Location: North Atlantic Ocean * Campaign: Leg209 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 29 cores; 147.6 m cored; 0 m drilled; 53.3 % recovery
209-1270A * Latitude: 14.722360 * Longitude: -44.888680 * Date/Time Start: 2003-05-28T22:00:00 * Date/Time End: 2003-05-29T16:00:00 * Elevation: -1951.0 m * Penetration: 26.9 m * Recovery: 3.28 m * Location: North Atlantic Ocean * Campaign: Leg209 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 4 cores; 26.9 m cored; 0 m drilled; 12.2 % recovery
209-1270B * Latitude: 14.721080 * Longitude: -44.887080 * Date/Time Start: 2003-05-29T16:00:00 * Date/Time End: 2003-05-31T12:00:00 * Elevation: -1909.9 m * Penetration: 45.9 m * Recovery: 17.17 m * Location: North Atlantic Ocean * Campaign: Leg209 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 10 cores; 45.9 m cored; 0 m drilled; 37.4 % recovery
Size:
9 datasets

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Datasets listed in this publication series

  1. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 1) Whole rock sulfur isotope and sulfur concentrations of rocks from ODP Hole 209-1268A. https://doi.org/10.1594/PANGAEA.734286
  2. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 1) Whole rock sulfur isotope and sulfur concentrations of rocks from ODP Hole 209-1272A. https://doi.org/10.1594/PANGAEA.734287
  3. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 1) Whole rock sulfur isotope and sulfur concentrations of rocks from ODP Site 209-1270. https://doi.org/10.1594/PANGAEA.734289
  4. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 1) Whole rock sulfur isotope and sulfur concentrations of rocks from ODP Site 209-1271. https://doi.org/10.1594/PANGAEA.734288
  5. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 2) Bulk rock oxygen isotope ratios of ODP Hole 209-1268A. https://doi.org/10.1594/PANGAEA.734291
  6. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 2) Bulk rock oxygen isotope ratios of ODP Hole 209-1272A. https://doi.org/10.1594/PANGAEA.734292
  7. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 2) Bulk rock oxygen isotope ratios of ODP Hole 209-1274A. https://doi.org/10.1594/PANGAEA.734293
  8. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 2) Bulk rock oxygen isotope ratios of ODP Site 209-1270. https://doi.org/10.1594/PANGAEA.734326
  9. Alt, JC; Shanks, WC; Paulick, H et al. (2007): (Table 2) Bulk rock oxygen isotope ratios of ODP Site 209-1275. https://doi.org/10.1594/PANGAEA.734325