A review of methods used to test periodicity of natural processes with a special focus on harmonic periodicities found in global U-Pb detrital zircon age distributions

The multitude of periodicities reported from detrital zircon and related geochemical time-series leads to questions about which cycles should be considered valid, which are byproducts of random noise, and the degree of uncertainty associated with the detected periodicities. To enhance understanding of detrital zircon periodicities, we review existing estimates by assessing both methodological reliability and reproducibility of results. Methods commonly employed include scalograms from wavelet analysis, periodograms from spectral analysis, and correlograms from cross-correlation analysis. This study analyzes possible zircon periodicities ranging from less than 1 million to 1 billion years. We systematically evaluate the capabilities of each approach, and then refine estimates in terms of their reproducibility using seven completely independent to partially independent U-Pb detrital zircon databases. Periodicities that are consistently found at high confidence levels are considered statistically significant, whereas those that cannot be replicated are considered as spurious. The comparative studies of detrital zircon ages reveal a dominant set of eight period-tripling cycles of ~0.373, 1.12, 3.35, 10.1, 30.2, 90.5, 272, and 815 myr (rounded to three digits). Additionally, a multitude of subordinate cycles are harmonically linked to the main period-tripling sequence. The detected periodicities often correspond to cycles found in large igneous province occurrence, seafloor spreading rates, million-year climatic cycles, mass extinctions, and other natural variation seemingly unrelated to geological processes. The commonality suggests a persistent episodic link between zircon production and other geological and non-geological processes throughout Earth's entire history. As a final step, we review a variety of hypotheses being explored to explain primary, secondary, and tertiary causes of cycles, and then propose tests that should soon be possible to either validate or falsify these diverse ideas.

Automated summary

This study systematically analyzes the detrital zircon ages to identify various periodicities, considering those consistently found at high confidence levels as statistically significant.