Cyclochronology of the Global Stratotype Section and Point for the Eocene/Oligocene boundary

Spectral analyses of high-resolution records from the upper Eocene-lower Oligocene from the Massignano section, GSSP for the Eocene/Oligocene (E/O) boundary, and the nearby Massicore reveal orbitally controlled fluctuations in the percent concentration of calcium carbonate (wt% CaCO 3 ) and magnetic susceptibility. Extraction of orbital components provides a consistent cyclochronology for the two sites that straddles the E/O boundary. Detection of longer-term modulation in the short eccentricity enabled tuning to the astronomical solution and development of a robust astrochronology for the E/O boundary transition in the GSSP section. Correlation with astrochronologically dated records allowed us to identify the local sedimentary response to the global paleoclimatic and palaeoceanographic events that characterize the greenhouse-icehouse transition during the late Eocene-early Oligocene. • The Massignano section is the reference for the Eocene/Oligocene boundary. • We provide an astrochronologically calibrated record of the Massignano GSSP. • The age model enables precise correlation of the standard Eocene/Oligocene boundary.