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Abstract Paleosecular variation analysis is a primary tool for characterizing ancient geomagnetic behavior and its evolution through time. This study presents a new high‐quality directional data set, paleosecular variation of the Paleogene (PSVP), with and without correction for serial correlation, compiled from 1,667 sites from 45 different localities from the Paleogene and late Cretaceous (84–23 Ma). The data set is used to study the variability, structure, and latitude dependence of the geomagnetic field during that period by varying selection criteria and PSV models. Modeled values for the equatorial virtual geomagnetic pole (VGP) dispersion have over‐lapping uncertainty intervals within their uncertainty bounds between 8.3° and 18.6° for the past 250 Ma. We investigate the suitability of two descriptive models of PSV, Model G‐style quadratic fits and covariant Giant Gaussian Process models, and find that both styles of model fail to satisfactorily reproduce the latitude dependent morphology of PSV, but suggest that estimates of the equatorial VGP dispersion may still robustly characterize aspects of Earth's long‐term field morphology. During this time where the PSV behavior has not changed substantially, the reversal frequency has varied widely. The lack of a clear relationship between PSV behavior and reversal frequency is not trivially explained in the context of published findings regarding numerical geodynamo simulations.

Abstract Statistical studies of paleosecular variation (PSV) are used to infer the structure and behavior of the geomagnetic field. This study presents a new database, paleosecular variation of the Miocene (PSVM), of high‐quality directional data from the Miocene Epoch (5.3–23 Ma), compiled from 1,454 sites from 44 different localities. This database is used to model the latitude dependence of paleosecular variation with varying selection criteria using a quadratic form based on Model G. Our fitted model parameter for latitude‐invariant PSV (Model G a) is 15.6° and the latitude dependent PSV term (Model G b) is 0.23. The latitude invariant term is substantially higher than previously observed for the past 10 Myrs or any other studied ages. We also present a new stochastic model of the time‐average field, BB‐M22, using a covariant giant Gaussian process (GGP) which is constrained using data from PSVM, PINT and Earth‐like geodynamo numerical simulations. BB‐M22 improves the fit to PSVM data relative to prior GGP models, as it reproduces the higher virtual geomagnetic pole (VGP) dispersion observed during the Miocene. Our findings suggest a more variable magnetic field and more active geodynamo in the Miocene Epoch than the past 10 Myrs, perhaps linked to elevated core‐mantle heat flow. Our results suggest that the average axial dipole dominance of the time‐instantaneous field was lower than in more recent times. We note however, that the inclination anomaly estimates, suggest that it cannot be ruled out that the Miocene time averaged field resembles a geocentric axial dipole.