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Université de Lyon, Centre des Sciences de la Terre, 27-43 Boulevard du 11 Novembre, 69622 Villeurbanne Cedex, France
High-frequency cycles can be used for setting accurate correlations within basins, between sites of the world-ocean or between two different continents. Besides, since Gilbert (1895, Journal of Geology, 3, 121–127), the cycles forming marl-limestone couplets have been regarded as chronostratigraphic tools for estimating durations of some stages, formations and biostratigraphical units. But this use is dangerous if applied without caution. Firstly, the period of decimetric couplets can vary along sedimentary successions because it is negatively correlated to the sedimentation rate. Indeed, in a dilated and quickly deposited series, many low-order cycles, unapparent in slowly deposited sediments because of bioturbation, occur as centrimetric to decimetric units and can be gathered in groups differing from the 100 ka bundles. Examples from the Lower and Middle Cretaceous show that 21 ka cycles are well-expressed with sedimentation rates of 5–30 m Ma–1. Secondly, the recording of orbital cycles depends on the facies and on the characteristics of sedimentary fluxes. Thirdly, corrections must be done for the variation of some orbital frequencies with time.
In summary, facies suitable for cyclostratigraphic work show moderate sedimentation rate, homogeneous lithologies with a balance of limestone and marl and are related to high sea-level periods which coincide generally with regular fluxes.
