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Tracing the origins and recurrence of the South Atlantic Anomaly: A 2000-year absolute paleointensity record from central South America.

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Title: Tracing the origins and recurrence of the South Atlantic Anomaly: A 2000-year absolute paleointensity record from central South America.
Authors: Gómez-Paccard, Miriam1 mgomezpaccard@csic.es, Javier Pavón-Carrasco, F.1,2, Chauvin, Annick3, Palencia-Ortas, Alicia4, Rivero-Montero, Mercedes5,6, Puente-Borque, Marina1,2, Campuzano, Saioa A.1,2, Adsuar, Aída1, Bonilla-Alba, Raquel7, del Río, Judit8, Velázquez-Martín, Regina1, Luisa Osete, María1,2, Gabriela Ortíz, María9, Amalia Zaburlín, María10,11, Marta Sampietro-Vattuone, María12, Martín Basso, Diego11, Luis Peña-Monné, José13, Otero, Clarisa14, Scaro, Agustina9
Source: Proceedings of the National Academy of Sciences of the United States of America. 5/19/2026, Vol. 123 Issue 20, p1-9. 37p.
Subjects: Magnetic anomalies, Geomagnetic variations, Geomagnetism, Magnetic dipole moments
Geographic Terms: South America, Southern Hemisphere
Abstract: A robust characterization of geomagnetic field strength in the Southern Hemisphere over the past millennia is critical for understanding the (multi)centennial evolution of the South Atlantic Anomaly (SAA), one of the most prominent geomagnetic features at Earth's surface. Yet, robust absolute paleointensity records remain scarce in this region, introducing significant uncertainty into geomagnetic field reconstructions. Here, we present 41 absolute archeointensity determinations obtained using the Thellier-Thellier method from central South America spanning the last two millennia. Combined with a selection of high-quality records from the same region, these new data yield virtual axial dipole moment values broadly consistent with the other few available Southern Hemisphere datasets but generally lower than those from Europe, indicating a persistent north-south asymmetry in geomagnetic field strength. A new global geomagnetic field model incorporating these new data suggests that the observed asymmetry reflects a persistently northward-shifted eccentric dipole. In addition, the model tentatively suggests a westward migration of a nondipolar low-intensity anomaly between 1 and 850 CE, from the Indian Ocean to northern South America, following a trajectory broadly similar to that of the modern SAA, which appears in the Indian Ocean after 1100 CE and progresses across Africa before reaching South America. These findings support the hypothesis of a recurrent large-scale geomagnetic pattern and highlight multiscale geodynamic control on geomagnetic field morphology, in which mantle and core processes interact to shape secular variation patterns on centennial to millennial timescales. [ABSTRACT FROM AUTHOR]
Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
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PubType: Academic Journal
PubTypeId: academicJournal
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  Data: Tracing the origins and recurrence of the South Atlantic Anomaly: A 2000-year absolute paleointensity record from central South America.
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  Data: A robust characterization of geomagnetic field strength in the Southern Hemisphere over the past millennia is critical for understanding the (multi)centennial evolution of the South Atlantic Anomaly (SAA), one of the most prominent geomagnetic features at Earth's surface. Yet, robust absolute paleointensity records remain scarce in this region, introducing significant uncertainty into geomagnetic field reconstructions. Here, we present 41 absolute archeointensity determinations obtained using the Thellier-Thellier method from central South America spanning the last two millennia. Combined with a selection of high-quality records from the same region, these new data yield virtual axial dipole moment values broadly consistent with the other few available Southern Hemisphere datasets but generally lower than those from Europe, indicating a persistent north-south asymmetry in geomagnetic field strength. A new global geomagnetic field model incorporating these new data suggests that the observed asymmetry reflects a persistently northward-shifted eccentric dipole. In addition, the model tentatively suggests a westward migration of a nondipolar low-intensity anomaly between 1 and 850 CE, from the Indian Ocean to northern South America, following a trajectory broadly similar to that of the modern SAA, which appears in the Indian Ocean after 1100 CE and progresses across Africa before reaching South America. These findings support the hypothesis of a recurrent large-scale geomagnetic pattern and highlight multiscale geodynamic control on geomagnetic field morphology, in which mantle and core processes interact to shape secular variation patterns on centennial to millennial timescales. [ABSTRACT FROM AUTHOR]
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  Data: <i>Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
PLink https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=194071187
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