CONCLUSIONS

  1. Sediments from Site 1077 contain large amounts of siliceous microfossils. The marine signal dominates, and marine diatoms are the most abundant siliceous microfossils group, followed by silicoflagellates and radiolarians.
  2. High abundances of diatoms, silicoflagellates, and radiolarians point to increased productivity during glacial stages and cooler conditions of Substages 5.2 and 5.4.
  3. An abrupt change in the amplitude of the siliceous signal as well as in the diatom assemblages is evident at Termination II. The system seems to change from predominantly marine to marine/brackish.
  4. The continental signal derived from freshwater diatoms shows two periods that can be correlated with humid conditions on land and/or northward movements of the Congo River plume during Stages 10 and 11 and during 28-119 ka.
  5. Fluctuations in the abundances of chrysophycean cysts may be used as indicators of changes in the extension of inland waters. They point to an abrupt reduction of the limnetic system, particularly during the last 125 k.y.
  6. Sedimentation rates showed highest values at Stage 11, between Stages 9 and 7, and between Stages 5 and 1 in correspondence to the northward movements of the ABF detected by the oceanic temperate diatom assemblage in combination with D. speculum (cold-water silicoflagellate).
  7. The opal signal recorded at Site 1075 correlates well with concentration of marine diatoms at the Site 1077 from ~120 ka to the present; differences in timing can be attributed to differences on the age model. Both parameters showed higher values during the last 125 k.y.
  8. TOC in sediments from Site 1075 is of marine origin, in agreement with the overwhelming dominance of marine siliceous microfossils.

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