Paleomagnetic evidence for long‐term (10⁴ year) Memory and periodic behavior in the Earth's core dynamo process

Abstract

A new paleomagnetic secular variation (PSV) record from the late Quaternary Wilson Creek beds of Mono Lake, California contains a distinctive periodic vector waveform that follows and is almost certainly related to the Mono Lake excursion. A comparison of all published PSV results from the Wilson Creek beds suggests that the magnetic field at Mono Lake went through an interval (36,000‐28,000 ybp) of very low amplitude PSV followed by the Mono Lake excursion (28,000‐27,000 ybp) and four subsequent recurrences (27,000‐12,500 ybp) of the excursion waveform with relatively diminished amplitudes (lower than the excursion amplitude but higher than PSV amplitudes at Mono Lake since 12,500 ybp). This pattern clearly suggests that the Mono Lake excursion is related to ‘typical’ PSV; it also suggests that the core dynamo process responsible for PSV is capable of near impulse onset, persistence over a time scale of 15,000 years, and quasi‐periodic behavior that is non‐wave‐length dispersive in time.