Cyclical Catastrophes?

[Recusant]

This is intriguing. Of course there are already recognized long-term (Milankovich) cycles in the life of our planet. Analysis of various data have produced hints that there may be one or more other long cycles. One hypothesis has to do with the undulation of the solar system in relation to the galactic plane.

"Earth's Greatest Catastrophes Seem to Follow a Mysterious 27-Million-Year Pulse" | ScienceAlert

Mass extinctions. Giant volcanic eruptions. Oceans suddenly deprived of oxygen.

At first glance, Earth's biggest geological disasters seem to have little in common beyond their sheer scale.

But for decades, scientists have wondered whether these seemingly unrelated events might actually follow a hidden rhythm stretching back hundreds of millions of years.

The possibility that Earth's geological history follows a long-term rhythm has been debated for decades.

The idea dates back to studies published in the 1980s, when researchers first proposed that mass extinctions and other major geological events might recur at regular intervals. Earlier studies identified similar periodic patterns, but the idea has remained controversial.

Now, an analysis published in Evolving Earth revisits that evidence using updated geological timescales and statistical methods.

The analysis concludes that the evidence for a roughly 27.5-million-year geological cycle has continued to strengthen, suggesting many of Earth's largest upheavals may be linked by long-term processes rather than representing isolated catastrophes.

Drawing on previously published geological datasets, New York University geologist Michael Rampino re-examined 89 major geological events spanning the past 260 million years using updated geological ages and statistical analyses.

The dataset includes marine mass extinctions, oceanic anoxic events, continental flood-basalt eruptions, sea-level fluctuations, terrestrial tetrapod extinctions, changes in seafloor spreading rates, and pulses of intraplate volcanism.

Together, these records reveal a dominant periodicity of approximately 27.5 million years, alongside a weaker cycle of around 8.9 million years.

[Continues . . .]

The paper is open access:

"The temporal characteristics of the geologic record: Global correlations and similar multi-million-year cycles of major geologic events with potential internal-Earth versus astronomical pacing" | Evolving Earth

Abstract:

Compilations of the latest updated high-precision radio-isotopic ages for a number of major geologic events of the last few hundred-million years, including aspects of global tectonics in the ocean basins and on continents, fluctuations in sea levels and resulting sedimentation patterns, pulses of active volcanism, variations in ocean/atmospheric composition and climatic changes, biodiversity, and mass-extinction events, are found to be closely temporally correlated at high statistical confidence levels. Furthermore, several methods of spectral analysis of the improved age data support the finding that these correlated events exhibit a common, statistically significant underlying multi-million-year cycle (or cycles) in the range of ∼26 to 36 My. Shorter cycles and harmonics from ∼6.4 to ∼13 My (especially at ∼9 My), and longer cycles (multiples) of ∼56 to 65-My, ∼93 My, ∼140 to 187-My, and ∼240 to 270-My, are also indicated statistically for some of these events.

These results support previous findings that major geologic events of various kinds are globally correlated, occur in pulses, and display common underlying periodicities. These potentially inter-related, periodic, geophysical/geological/biological events might be linked to internal Earth dynamics associated with surges in mantle convection and plume initiation, and interactions with subduction, that may modulate plate movements and hotspot activity with an ∼30 My cycle.

On the other hand, the ∼26- to 36-My periodicities detected in the geologic age data are in agreement with a double cycle (∼26 and 33 My) that appears in amplitude variations of the Earth's 2.4- to 9-My orbital eccentricity cycles in the Solar System, and also with known cycles of the Earth's astronomical motions within the Milky Way Galaxy. Several scenarios have been proposed in which these astronomical cycles, interacting with terrestrial processes, might affect the timing of global geological activity. The similarities in the astronomical and geological periodicities point to the prospect of some degree of extra-terrestrial pacing of major geological events, along with the potential for astronomical "tuning" of multi-million-year terrestrial global geologic activity.