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Francois, Roger; Bacon, Michael P; Suman, Daniel O (1990): Radionuclides and accumulation rates of sediments from the equatorial Atlantic. PANGAEA, https://doi.org/10.1594/PANGAEA.727171, Supplement to: Francois, R et al. (1990): Thorium 230 profiling in deep-sea sediments: high resolution records of flux and dissolution of carbonate in the equatorial Atlantic during the last 24,000 years. Paleoceanography, 5(5), 761-787, https://doi.org/10.1029/PA005i005p00761

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Abstract:
Variations in carbonate flux and dissolution, which occurred in the equatorial Atlantic during the last 24,000 years, have been estimated by a new approach that allows the point-by-point determination of paleofluxes to the seafloor. An unprecedented time resolution can thus be obtained which allows sequencing of the relatively rapid events occurring during deglaciation. The method is based on observations that the flux of unsupported 230Th into deep-sea sediments is nearly independent of the total mass flux and is close to the production rate. Thus excess 230Th activity in sediments can be used as a reference against which fluxes of other sedimentary components can be estimated. The study was conducted at two sites (Ceará Rise; western equatorial Atlantic, and Sierra Leone Rise; eastern equatorial Atlantic) in cores raised from three different depths at each site. From measurements of 230Th and CaCO3, changes in carbonate flux with time and depth were obtained. A rapid increase in carbonate production, starting at the onset of deglaciation, was found in both areas. This event may have important implications for the postglacial increase in atmospheric CO2 by increasing the global carbonate carbon to organic carbon rain ratio and decreasing the alkalinity of surface waters (and possibly the North Atlantic Deep Water). Increased carbonate dissolution occurred in the two regions during deglaciation, followed by a minimum during mid-Holocene and renewed intensification of dissolution in late Holocene. During the last 16,000 years, carbonate dissolution was consistently more pronounced in the western than in the eastern basin, reflecting the influence of Antarctic Bottom Water in the west. This trend was reversed during stage 2, possibly due to the accumulation of metabolic CO2 below the level of the Romanche Fracture Zone in the eastern basin.
Coverage:
Median Latitude: 4.281333 * Median Longitude: -31.717000 * South-bound Latitude: 2.460000 * West-bound Longitude: -43.487000 * North-bound Latitude: 4.948000 * East-bound Longitude: -19.762000
Date/Time Start: 1981-05-27T00:00:00 * Date/Time End: 1984-11-08T00:00:00
Event(s):
EN066-21PG (0021PG) * Latitude: 4.233000 * Longitude: -20.625000 * Date/Time: 1981-05-27T00:00:00 * Elevation: -3792.0 m * Campaign: EN06601 * Basis: Endeavor * Device: Gravity corer (GC)
EN066-29PG (0029PG) * Latitude: 2.460000 * Longitude: -19.762000 * Date/Time: 1981-05-29T00:00:00 * Elevation: -5105.0 m * Campaign: EN06601 * Basis: Endeavor * Device: Gravity corer (GC)
EN066-38PG (0038PG) * Latitude: 4.918000 * Longitude: -20.498000 * Date/Time: 1981-05-31T00:00:00 * Elevation: -2937.0 m * Campaign: EN06601 * Basis: Endeavor * Device: Gravity corer (GC)
Size:
12 datasets

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Datasets listed in this Collection

  1. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core EN066-21PG. https://doi.org/10.1594/PANGAEA.727165
  2. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core EN066-29PG. https://doi.org/10.1594/PANGAEA.727166
  3. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core EN066-38PG. https://doi.org/10.1594/PANGAEA.727167
  4. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core KNR110-0055GGC. https://doi.org/10.1594/PANGAEA.727168
  5. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core KNR110-0058GGC. https://doi.org/10.1594/PANGAEA.727169
  6. Francois, R; Bacon, MP; Suman, DO (1990): (Table 1) Age model of sediment core KNR110-0082GGC. https://doi.org/10.1594/PANGAEA.727170
  7. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core EN066-21PG. https://doi.org/10.1594/PANGAEA.357171
  8. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core EN066-29PG. https://doi.org/10.1594/PANGAEA.357172
  9. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core EN066-38PG. https://doi.org/10.1594/PANGAEA.357169
  10. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core KNR110-0055GGC. https://doi.org/10.1594/PANGAEA.357170
  11. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core KNR110-0058GGC. https://doi.org/10.1594/PANGAEA.357167
  12. Francois, R; Bacon, MP; Suman, DO (1990): (Table 2) Radionuclides and accumulation rate of sediment core KNR110-0082GGC. https://doi.org/10.1594/PANGAEA.357168