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Tiedemann, Ralf; Sarnthein, Michael; Stein, Ruediger (1989): Biogenic and terrigeneous components in ODP Leg 108 holes [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.746249, Supplement to: Tiedemann, R et al. (1989): Climatic changes in the western Sahara: aeolo-marine sediment record of the last 8 million years (Sites 657-661). In: Ruddiman, W; Sarnthein, M; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 108, 241-277, https://doi.org/10.2973/odp.proc.sr.108.169.1989

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Abstract:
Five Ocean Drilling Program sites (657-661), which form a north-south transect off the western periphery of the Sahara, were selected to measure the long-term history of Saharan/Sahelian dust flux and fluvial sediment discharge and the fluxes of marine CaCO3 and opal over the last 8 m.y. Sites 658 and 659 served for high-resolution studies, and Sites 657, 660, and 661 for insights into the spatial patterns of dust flux. The nearshore mean flux of opal off Cap Blanc (21 °N) showed an abrupt increase about 3 Ma that appears to reflect the main onset of coastal upwelling fertility and enhanced trade winds. At the same time, the input of river-borne clay strongly decreased, suggesting a dry up of the central Saharan rivers. Later, marked short-lived spikes of clay and opal may indicate ongoing ephemeral pulses of fluvial runoff linked to peak interglacial stages.
Given the zonal dust discharge centered near 18 °N at Site 659, the aridification of the south Sahara and Sahel increased in several steps: at 4.6, 4.3, and especially at 4.0, 3.6, and 2.1 Ma, and again, at 0.8 Ma. The late Miocene and earliest Pliocene were humid. Although the central and north Saharan climate appears to be linked to the glaciation history of the Northern Hemisphere, the long-term aridification further south followed a different schedule. The spatial distribution of quartz accumulation suggests that the dust outbreaks linked to the Intertropical Convergence Zone during summer did not shift in latitude back to 4.0 Ma, at least. The short-term variations of dust output over the last 0.5 m.y. followed orbital scale pulses with a strong precessional signal, showing a link of Sahelian humidity changes to the variation of sea-surface temperature and evaporation in the tropical Atlantic.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 17.385557 * Median Longitude: -19.816729 * South-bound Latitude: 9.446800 * West-bound Longitude: -21.026200 * North-bound Latitude: 21.331500 * East-bound Longitude: -18.580800
Date/Time Start: 1986-02-27T00:00:00 * Date/Time End: 1986-03-21T00:00:00
Event(s):
108-657 * Latitude: 21.331500 * Longitude: -20.948800 * Date/Time Start: 1986-02-27T00:00:00 * Date/Time End: 1986-03-03T00:00:00 * Elevation: -4232.0 m * Penetration: 344.3 m * Recovery: 261.1 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 38 cores; 344.3 m cored; 0 m drilled; 75.8% recovery
108-658 * Latitude: 20.749200 * Longitude: -18.580800 * Date/Time Start: 1986-03-04T00:00:00 * Date/Time End: 1986-03-08T00:00:00 * Elevation: -2274.0 m * Penetration: 537.1 m * Recovery: 541.5 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Composite Core (COMPCORE) * Comment: 59 cores; 537.1 m cored; 0 m drilled; 100.8% recovery
108-658A * Latitude: 20.749200 * Longitude: -18.580800 * Date/Time Start: 1986-03-04T15:15:00 * Date/Time End: 1986-03-07T01:15:00 * Elevation: -2274.0 m * Penetration: 300.4 m * Recovery: 294.98 m * Location: Canarias Sea * Campaign: Leg108 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 300.4 m cored; 0 m drilled; 98.2 % recovery
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
7 datasets

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Datasets listed in this publication series

  1. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Appendix A) Physical properties, grain size, and bulk mineralogy of ODP Site 108-657. https://doi.org/10.1594/PANGAEA.746244
  2. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Table 3) Turbidite abundance at ODP Site 108-657 during the last 6.5 Ma. https://doi.org/10.1594/PANGAEA.746242
  3. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Appendix B) Physical properties, grain size, and bulk mineralogy of ODP Site 108-658. https://doi.org/10.1594/PANGAEA.746245
  4. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Table 4) Stratigraphic position and opal contents of samples with relative excess to clay at ODP Hole 108-658A. https://doi.org/10.1594/PANGAEA.746243
  5. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Appendix C) Physical properties, grain size, and bulk mineralogy of ODP Site 108-659. https://doi.org/10.1594/PANGAEA.746246
  6. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Appendix D) Physical properties, grain size, and bulk mineralogy of ODP Site 108-660. https://doi.org/10.1594/PANGAEA.746247
  7. Tiedemann, R; Sarnthein, M; Stein, R (1989): (Appendix D) Physical properties, grain size, and bulk mineralogy of ODP Site 108-661. https://doi.org/10.1594/PANGAEA.746248