PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs
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 1,4...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Wiley
2022-08-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2022GC010480 |
| _version_ | 1797638131563888640 |
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| author | Y. A. Engbers R. K. Bono A. J. Biggin |
| author_facet | Y. A. Engbers R. K. Bono A. J. Biggin |
| author_sort | Y. A. Engbers |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-03-11T12:58:47Z |
| format | Article |
| id | doaj.art-ac6b7ef74b7244c6972d768270495d69 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:58:47Z |
| publishDate | 2022-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-ac6b7ef74b7244c6972d768270495d692023-11-03T16:55:35ZengWileyGeochemistry, Geophysics, Geosystems1525-20272022-08-01238n/an/a10.1029/2022GC010480PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 MyrsY. A. Engbers0R. K. Bono1A. J. Biggin2Geomagnetism Laboratory Department of Earth, Ocean and Ecological Sciences University of Liverpool Liverpool UKGeomagnetism Laboratory Department of Earth, Ocean and Ecological Sciences University of Liverpool Liverpool UKGeomagnetism Laboratory Department of Earth, Ocean and Ecological Sciences University of Liverpool Liverpool UKAbstract 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.https://doi.org/10.1029/2022GC010480paleosecular variationMiocenecore convection |
| spellingShingle | Y. A. Engbers R. K. Bono A. J. Biggin PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs Geochemistry, Geophysics, Geosystems paleosecular variation Miocene core convection |
| title | PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs |
| title_full | PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs |
| title_fullStr | PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs |
| title_full_unstemmed | PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs |
| title_short | PSVM: A Global Database for the Miocene Indicating Elevated Paleosecular Variation Relative to the Last 10 Myrs |
| title_sort | psvm a global database for the miocene indicating elevated paleosecular variation relative to the last 10 myrs |
| topic | paleosecular variation Miocene core convection |
| url | https://doi.org/10.1029/2022GC010480 |
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