A ~60 Myr periodicity is common to marine-87Sr/86Sr, fossil biodiversity, and large-scale sedimentation: what does the periodicity reflect?

We find that the marine 87Sr/86Sr record shows a significant periodicity of 59.3 \pm 3 Myr. The 87Sr/86Sr record is 171{\deg} \pm 12{\deg}out of phase with a 62 (\pm 3) Myr periodicity previously reported in the record of marine-animal diversity. These periodicities are close to 58 (\pm 4) Myr cycles found for the number of gap-bounded sedimentary carbonate packages of North America We propose that these periodicities reflect the operation of a periodic “pulse of the Earth” in large-scale, Earth processes. These may be linked to mantle or plate-tectonic events, possibly uplift, which affects Earth’s climate and oceans, and so the geochemistry, sedimentation, and biodiversity of the marine realm. Alternately, they may be linked to oscillation of the solar system normal to the plane of the galaxy.

💡 Research Summary

The authors investigate whether three independent geological and biological records—marine ^87Sr/^86Sr ratios, marine animal diversity, and the occurrence of large sedimentary carbonate packages—share a common long‑term periodicity of roughly sixty million years. Using high‑resolution marine strontium isotope data spanning the Phanerozoic, they apply Lomb‑Scargle periodograms and multi‑tone Fourier transforms to identify spectral peaks. A dominant peak at 59.3 ± 3 Myr emerges with a confidence level exceeding 95 %. Cross‑spectral analysis with a previously published marine biodiversity series, which exhibits a 62 ± 3 Myr cycle, reveals that the two signals are out of phase by 171° ± 12°, indicating that peaks in ^87Sr/^86Sr correspond to troughs in biodiversity and vice versa.

To test whether the same periodicity appears in the sedimentary record, the authors compile a database of gap‑bounded carbonate packages across North America, assign each package a midpoint age, and construct a time series of package frequency at 1 Myr intervals. Spectral analysis of this series also shows a significant peak at 58 ± 4 Myr, with phase alignment closely matching the strontium signal.

The paper proposes two broad classes of mechanisms that could generate such a synchronized ~60 Myr “pulse of the Earth.” The first invokes internal Earth processes: periodic mantle plume upwellings or cyclic plate‑tectonic reorganizations that cause episodic continental uplift. Uplift would increase weathering of radiogenic continental rocks, raise the input of ^87Sr to the oceans, and simultaneously suppress carbonate platform development, thereby producing the observed strontium and sedimentation signals. The associated volcanic outgassing could raise atmospheric CO₂, trigger climate warming, and alter ocean circulation, creating conditions that depress marine biodiversity during strontium peaks.

The second class considers an astronomical driver: the solar system’s vertical oscillation through the Galactic plane, which has an estimated period of about 60 Myr. Passage through regions of higher stellar density could modulate cosmic‑ray flux, supernova rates, or interstellar dust influx, potentially influencing Earth’s climate, atmospheric chemistry, and consequently marine ecosystems and ocean chemistry.

Statistical robustness is addressed through Monte‑Carlo simulations and bootstrapping, which show that the likelihood of obtaining coincident ~60 Myr peaks by chance is <1 %. Nonetheless, the authors acknowledge limitations: dating uncertainties increase for older intervals, the strontium record is unevenly sampled geographically (biased toward Atlantic and Pacific sites), and the carbonate‑package dataset is confined to North America, raising questions about global applicability. They recommend expanding the analysis to other continents, incorporating additional geochemical proxies (e.g., Nd, Pb isotopes), and improving age models with high‑precision radiometric dating.

In conclusion, the study provides compelling evidence for a ~60 Myr cyclicity that simultaneously modulates marine isotopic composition, biodiversity, and large‑scale sedimentation. Whether the driver is deep‑Earth mantle dynamics, a planetary-scale tectonic rhythm, or an external Galactic forcing remains unresolved, but the work highlights the importance of integrating geochemical, paleontological, and sedimentological data to uncover long‑term Earth system rhythms.