More and more paleoceanographic studies are performed on different size fractions of deep-sea sediments. Although it has been a controversial issue for some time, the bioturbation process depends on the particle size and can, in principle, decouple paleoceanographic records obtained in the same core. This problem is studied by using a simple mixing model which allows the derivation of analytical equations for both the expected phase shift and relative attenuation of signals carried by different size fractions. Depending on several parameters, the time shift and relative attenuation can be on the order of a few millenia and 50%, respectively. However, high sedimentation rates (>10--20 cm/kyr) minimize these potential complications allowing us to study millenium-scale events in well-chosen sedimentary environments. ¿ 2001 American Geophysical Union