Cyclostratigraphy and recent developments in the astronomical calibration of the Geological Time Scale

Abstract

Cyclic astronomical variations affect the distribution of solar energy on the Earth’s surface, which induces climatic changes detected in the sedimentary records. Such changes have been demonstrated to vary in tune with the classical Milankovitch frequency band (about 10 to 500 kyr). Correlations of high-fidelity stratigraphy with well constrained astronomical models have allowed unprecedented temporal resolution of several intervals of the Cenozoic and Mesozoic eras. Recent studies have highlighted million-year (Myr) to multi-Myr periodic variations in the astronomical and geological time series. These low-frequency cycles mainly result from the interference of the fundamental high-frequency cycles (precession, obliquity, eccentricity); modeling has shown that they have played an important role in paleoclimatic and paleoenvironmental changes. The detection of the astronomical periodicties in the sedimentary records is thus of paramount interest because they provide constraints on geochronology and on how our climate is driven and responds to external forcing. Therefore, multiple efforts have continued to astronomically calibrate the geological time scales for potential implications in understanding rates and velocities of geological processes and events that occurred during Earth’s history. Keywords: Earth’s orbital parameters, astronomical models, Milankovitch, cyclostratigraphy, astronomical time scale, long-term orbital periods