Late Quaternary biogenic opal sedimentation and diatom assemblages in Congo Fan sediments.

Fluctuations in the sedimentation of biogenic opal and diatoms in the Congo Fan area (Lower Congo Basin off west Africa) during the past 1 million years in the Late Quatemary are the central topics of this thesis. Sediments of ODP Site 1077 (5°1O'S, 10° 26'E; 2,382 m water depth) were analyzed. The time interval studied, the last million year in the Late Quatemary, is a very interesting time in the global climate system when a change from a predominantly 41 kyr cyclicity in the early Pleistocene to the late Quaternary 100 kyr ice age cycles took place. This shift occurred around 800 to 900 ka, following the so-called Mid-Pleistocene Transition. The origin ofthe 100 kyr age cycle dominating the late Pleistocene is an issue not yet fully understood (Imbrie et al., 1993; In: Paleoceanography, 8: 699-735) because the direct influence of eccentricity on insolation is by far too small to produce the corresponding climate style.