In a new study published in the journal Geoscience Frontiers, a team of U.S. researchers analyzed the ages of 89 well-dated geological events of the last 260 million years — such as marine and non-marine extinctions, major ocean-anoxic events, sea-level fluctuations — from the recent geologic literature.
A study by Rampino et al. suggests that global geologic events are generally correlated, and seem to come in pulses with an underlying 27.5-million-year cycle. Image credit: NASA’s Goddard Space Flight Center Conceptual Image Lab.
“Many geologists believe that geological events are random over time,” said Professor Michael Rampino, a geologist in the Department of Biology at New York University.
“But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random.”
Using the age-dating data, Professor Rampino and colleagues performed moving-window and spectral analyses on the record of 89 major geologic events of the last 260 million years, including marine and non-marine extinctions, ocean-anoxic events, sea-level oscillations, continental flood-basalt eruptions, pulses of intra-plate magmatism, and changes in seafloor spreading rates.
The scientists found that these geologic events are generally clustered at 10 different timepoints over the 260 million years, grouped in peaks or pulses of roughly 27.5 million years apart.
The most recent cluster of geological events was approximately 7 million years ago, suggesting that the next pulse of major geological activity is more than 20 million years in the future.
The authors posit that these pulses may be a function of cycles of activity in the Earth’s interior–geophysical processes related to the dynamics of plate tectonics and climate. However, similar cycles in the Earth’s orbit in space might also be pacing these events.
“The correlations and cyclicity seen in the geologic episodes may be entirely a function of global internal Earth dynamics affecting global tectonics and climate, but similar cycles in the Earth’s orbit in the Solar System and in the Milky Way Galaxy might be pacing these events,” they said.
“Whatever the origins of these cyclical episodes, their occurrences support the case for a largely periodic, coordinated, and intermittently catastrophic geologic record, which is quite different from the views held by most geologists.”
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Michael R. Rampino et al. 2021. A pulse of the Earth: A 27.5-Myr underlying cycle in coordinated geological events over the last 260 Myr. Geoscience Frontiers 12 (6): 101245; doi: 10.1016/j.gsf.2021.101245
