CYCLOSTRATIGRAPHY AND CLIMATIC EUSTASY - EXAMPLE OF THE RUPELIAN STRATOTYPE

The Boom Clay Formation is a well-bedded deposit. Cycles have been rec ognised through grain-size variations, organic matter contents, carbon ate beds, bed thicknesses, and the analysis of clay minerals, trace el ements and stable isotopes. Orbital cycles are present with a dominanc e of the 100 ka periodicity but also cycles with lower frequency could be identified, which are interpreted as eustatic sequences. The mecha nism for the different cyclicities is glacio-eustatism. The clay miner alogy, geochemistry and the isotopes mainly reflect the varying terres trial versus marine influence. The evolution of the bed thickness cont ains a tectonic signal.