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Riedinger, Natascha; Pfeifer, Kerstin; Kasten, Sabine; Garming, Johanna Fredrika Luk; Vogt, Christoph; Hensen, Christian (2005): Geochemical and rock magnetic investigation of sediment cores of the western South Atlantic. PANGAEA, https://doi.org/10.1594/PANGAEA.737976, Supplement to: Riedinger, N et al. (2005): Diagenetic alteration of magnetic signals by anaerobic oxidation of methane related to a change in sedimentation rate. Geochimica et Cosmochimica Acta, 69, 4117-4126, https://doi.org/10.1016/j.gca.2005.02.004

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Abstract:
Geochemical and rock magnetic investigations of sediments from three sites on the continental margin off Argentina and Uruguay were carried out to study diagenetic alteration of iron minerals driven by anaerobic oxidation of methane (AOM). The western Argentine Basin represents a suitable sedimentary environment to study nonsteady-state processes because it is characterized by highly dynamic depositional conditions. Mineralogic and bulk solid phase data document that the sediment mainly consists of terrigenous material with high contents of iron minerals. As a typical feature of these deposits, distinct minima in magnetic susceptibility (k) are observed. Pore water data reveal that these minima in susceptibility coincide with the current depth of the sulfate/methane transition (SMT) where HS- is generated by the process of AOM. The released HS- reacts with the abundant iron (oxyhydr)oxides resulting in the precipitation of iron sulfides accompanied by a nearly complete loss of magnetic susceptibility. Modeling of geochemical data suggest that the magnetic record in this area is highly influenced by a drastic change in mean sedimentation rate (SR) which occurred during the Pleistocene/Holocene transition. We assume that the strong decrease in mean SR encountered during this glacial/interglacial transition induced a fixation of the SMT at a specific depth. The stagnation has obviously enhanced diagenetic dissolution of iron (oxyhydr)oxides within a distinct sediment interval. This assumption was further substantiated by numerical modeling in which the mean SR was decreased from 100 cm/kyr during glacial times to 5 cm/kyr in the Holocene and the methane flux from below was fixed to a constant value. To obtain the observed geochemical and magnetic patterns, the SMT must remain at a fixed position for ~9000 yrs. This calculated value closely correlates to the timing of the Pleistocene/Holocene transition. The results of the model show additionally that a constant high mean SR would cause a concave-up profile of pore water sulfate under steady state conditions.
Related to:
Riedinger, Natascha (2005): Preservation and diagenetic overprint of geochemicaland geophysical signals in ocean margin sedimentsrelated to depositional dynamics. Berichte aus dem Fachbereich Geowissenschaften der Universität Bremen, 242, 91 pp, urn:nbn:de:gbv:46-diss000013059
Coverage:
Median Latitude: -37.416283 * Median Longitude: -52.098667 * South-bound Latitude: -39.301700 * West-bound Longitude: -53.965000 * North-bound Latitude: -35.740300 * East-bound Longitude: -49.681000
Date/Time Start: 1999-12-19T05:13:00 * Date/Time End: 2000-01-07T16:05:00
Event(s):
GeoB6223-5 * Latitude Start: -35.740500 * Longitude Start: -49.681000 * Latitude End: -35.740500 * Longitude End: -49.681000 * Date/Time: 1999-12-19T05:13:00 * Elevation Start: -4280.0 m * Elevation End: -4280.0 m * Recovery: 8.15 m * Campaign: M46/2 * Basis: Meteor (1986) * Device: Gravity corer (Kiel type) (SL)
GeoB6223-6 * Latitude Start: -35.740300 * Longitude Start: -49.681000 * Latitude End: -35.740300 * Longitude End: -49.681000 * Date/Time: 1999-12-19T08:06:00 * Elevation Start: -4280.0 m * Elevation End: -4280.0 m * Recovery: 8.67 m * Campaign: M46/2 * Basis: Meteor (1986) * Device: Gravity corer (Kiel type) (SL) * Comment: core for geochemistry
GeoB6229-6 * Latitude Start: -37.206800 * Longitude Start: -52.650000 * Latitude End: -37.206800 * Longitude End: -52.650000 * Date/Time: 1999-12-25T22:24:00 * Elevation Start: -3446.0 m * Elevation End: -3446.0 m * Recovery: 9.5 m * Campaign: M46/2 * Basis: Meteor (1986) * Device: Gravity corer (Kiel type) (SL) * Comment: core for geochemistry
Size:
12 datasets

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Datasets listed in this publication series

  1. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Geochemical data (solid phase) of sediment core GeoB6223-6. https://doi.org/10.1594/PANGAEA.269147
  2. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Geochemical data (solid phase) of sediment core GeoB6229-6. https://doi.org/10.1594/PANGAEA.269148
  3. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Geochemical data (solid phase) of sediment core GeoB6308-4. https://doi.org/10.1594/PANGAEA.269149
  4. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Hydrogen sulphide of pore water from sediment core GeoB6308-4. https://doi.org/10.1594/PANGAEA.269290
  5. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Hydrogen sulphide, sulphate and iron of pore water from sediment core GeoB6223-6. https://doi.org/10.1594/PANGAEA.269152
  6. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Methane content of pore water from sediment core GeoB6223-6. https://doi.org/10.1594/PANGAEA.269150
  7. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Methane content of pore water from sediment core GeoB6229-6. https://doi.org/10.1594/PANGAEA.269151
  8. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Sulphate and iron of pore water from sediment core GeoB6308-4. https://doi.org/10.1594/PANGAEA.269289
  9. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Sulphate, iron and sulphide of pore water from sediment core GeoB6229-6. https://doi.org/10.1594/PANGAEA.269568
  10. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Susceptibility of sediment core GeoB6223-5. https://doi.org/10.1594/PANGAEA.269144
  11. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Susceptibility of sediment core GeoB6229-6. https://doi.org/10.1594/PANGAEA.269145
  12. Riedinger, N; Pfeifer, K; Kasten, S et al. (2005): Susceptibility of sediment core GeoB6308-4. https://doi.org/10.1594/PANGAEA.269146