Long-term cyclicities in Phanerozoic sea-level sedimentary record and their potential drivers

Cyclic sedimentation has varied at several timescales and this variability has been geologically well documented at Milankovitch timescales, controlled in part by climatically (insolation) driven sea-level changes. At the longer (tens of Myr) timescales connection between astronomical parameters and sedimentation via cyclic solar-system motions within the Milky Way has also been proposed, but this hypothesis remains controversial because of the lack of long geological records. In addition, the absence of a meaningful physical mechanism that could explain the connection between climate and astronomy at these longer timescales led to the more plausible explanation of plate motions as the main driver of climate and sedimentation through changes in ocean and continent mass distribution on Earth. Here we statistically show a prominent and persistent similar to 36 Myr sedimentary cyclicity superimposed on two megacycles (similar to 250 Myr) in a relatively well-constrained sea-level (SL) record of the past 542 Myr (Phanerozoic- eon). We also show two other significant similar to 9.3 and similar to 91 Myr periodicities, but with lower amplitudes. The similar to 9.3 Myr cyclicity was previously attributed to long-period Milankovitch band based on the Cenozoic record. However, the similar to 91 Myr cyclicity has never been observed before in the geologic record. The similar to 250 Myr cyclicity was attributed to the Wilson tectonic (supercontinent) cycle. The similar to 36 Myr periodicity, also detected for the first time in SL record, has previously been ascribed either to tectonics or to astronomical cyclicity. Given the possible link between amplitudes of the similar to 36 and similar to 250 Myr cyclicities in SL record and the potential that these periodicities fall into the frequency band of solar system motions, we suggest an astronomical origin, and model these periodicities as originating from the path of the solar system in the Milky Way as vertical and radial periods that modulate the flux of cosmic rays on Earth. Our finding of the similar to 36 Myr SL cyclicity lends credibility to the existing hypothesis about the imprint of solar-system vertical period on the geological record. The similar to 250 Myr megacycles are tentatively attributed to a radial period. However, tectonic causal mechanisms remain equally plausible. The potential existence of a correlation between the modeled astronomical signal and the geological record may offer an indirect proxy to understand the structure and history of the Milky Way by providing a 542 Myr long record of the path of the Sun in our Galaxy.