Orbital calibration of the Early Kimmeridgian (southeastern France): implications for geochronology and sequence stratigraphy.

Classic stratigraphic methods rarely provide high-resolution correlations between intrabasinal sedimentary sequences, which are important to understand the origin of sedimentation process and its environmental change. In this study, we investigate high-resolution cyclostratigraphic correlation from magnetic susceptibility in two Early Kimmeridgian pelagic marl-limestone successions, at La Méouge and Châteauneuf-d'Oze, southeastern France. Spectral analysis reveals the complete suite of orbital frequencies (precession, obliquity, and eccentricity) with the marl-limestone couplets being primarily precession-driven. Frequencies detected by the spectral analysis are similar between the sections, but their relative amplitudes are somewhat different, linked to the palaeoenvironmental position and the completeness of the sections. High-resolution correlation reveals two significant hiatuses at Châteauneuf-d’Oze. Early Kimmeridgian Platynota, Hypselocyclum, and Divisum ammonite zones were orbitally calibrated for an ultra-high resolution assessment of geological time. Finally, strong 405-kyr eccentricity cycles are recorded as third-order depositional sequences. [ABSTRACT FROM AUTHOR]