Removing Climatic Overprints in Sedimentary Cosmogenic Beryllium Records: Potentials and Limits.
| Title: | Removing Climatic Overprints in Sedimentary Cosmogenic Beryllium Records: Potentials and Limits. |
|---|---|
| Authors: | Savranskaia, Tatiana, Egli, Ramon, Simon, Quentin, Valet, Jean‐Pierre, Bassinot, Franck, Thouveny, Nicolas |
| Source: | Geochemistry, Geophysics, Geosystems: G3; Dec2024, Vol. 25 Issue 12, p1-26, 26p |
| Subject Terms: | GEOMAGNETIC variations, MAGNETIC field measurements, COSMOGENIC nuclides, CLIMATE change, PRINCIPAL components analysis, GEOMAGNETISM |
| Abstract: | Continuous reconstructions of past variations of the Earth's magnetic field are based mainly on paleomagnetic and cosmogenic 10Be records in marine sediments. In both cases, the recording mechanisms can be affected by environmental processes. Climatic overprints are only partially removed by normalization procedures, so that stacking is used to further remove site‐specific effects. Regionally or globally correlated artifacts, however, cannot be removed by stacking. Here we present a modified approach where geomagnetic records are complemented by environmental proxies representing processes that might affect the field recording mechanism. Geomagnetic and environmental records are jointly processed with principal component analysis to obtain a set of components supposed to represent true variations of the geomagnetic field and climatic overprints, respectively. After discussing the theoretical background of this new approach and its underlying assumptions, a practical example is presented, using a worst‐case scenario based on a single 10Be record from the North Atlantic with strong climatic overprints, covering the last 600 ka. The first two principal components, which represent the modulation of 10Be by global climatic variations and by the geomagnetic field, respectively, explain 66.3% of the signal variance. Comparison of the geomagnetic principal component with global relative paleointensity stacks shows that the original climatic overprint can be reduced by a factor of 2, outperforming a 10Be/9Be stack obtained from two sites with little glacial‐interglacial variability. The proposed method for removing climatic overprints can be applied to multiple sites more efficiently than conventional stacking. Plain Language Summary: Continuous records of the Earth's magnetic field rely on measurements of magnetic minerals or cosmogenic isotopes in sediments. Both types of records are also sensitive to environmental conditions and are thus affected by past climatic variations. These unwanted climatic overprints are difficult to remove: one strategy consists in stacking records from different sites; however, regionally or globally correlated artifacts cannot be completely removed by this technique. Here we present a new method for separating the geomagnetic signal from unwanted climatic overprint, which is based on the principal component analysis (PCA). The efficiency of this new method is tested with a worst‐case example based on a single site located in the North Atlantic, which is characterized by strong glacial‐interglacial variability. The first two principal components obtained from PCA represent the modulation of 10Be by global climatic variations and by the geomagnetic field, respectively. Comparisons of the geomagnetic field component with reference data show that the original climatic overprint has been reduced by a factor of 2, outperforming a 10Be/9Be stack obtained from two sites with little glacial‐interglacial variability. The proposed method for removing climatic overprints can be applied to multiple sites more efficiently than conventional stacking. Key Points: A new technique for removing climatic overprints from geomagnetic records is presentedA worst‐case example based on a single cosmogenic 10Be record yields a reduction of environmental overprints by a factor of 2Cosmogenic 10Be is a better geomagnetic field proxy for the North Atlantic Ocean than 10Be normalized by 9Be [ABSTRACT FROM AUTHOR] |
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| Database: | Complementary Index |
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| Items | – Name: Title Label: Title Group: Ti Data: Removing Climatic Overprints in Sedimentary Cosmogenic Beryllium Records: Potentials and Limits. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Savranskaia%2C+Tatiana%22">Savranskaia, Tatiana</searchLink><br /><searchLink fieldCode="AR" term="%22Egli%2C+Ramon%22">Egli, Ramon</searchLink><br /><searchLink fieldCode="AR" term="%22Simon%2C+Quentin%22">Simon, Quentin</searchLink><br /><searchLink fieldCode="AR" term="%22Valet%2C+Jean‐Pierre%22">Valet, Jean‐Pierre</searchLink><br /><searchLink fieldCode="AR" term="%22Bassinot%2C+Franck%22">Bassinot, Franck</searchLink><br /><searchLink fieldCode="AR" term="%22Thouveny%2C+Nicolas%22">Thouveny, Nicolas</searchLink> – Name: TitleSource Label: Source Group: Src Data: Geochemistry, Geophysics, Geosystems: G3; Dec2024, Vol. 25 Issue 12, p1-26, 26p – Name: Subject Label: Subject Terms Group: Su Data: <searchLink fieldCode="DE" term="%22GEOMAGNETIC+variations%22">GEOMAGNETIC variations</searchLink><br /><searchLink fieldCode="DE" term="%22MAGNETIC+field+measurements%22">MAGNETIC field measurements</searchLink><br /><searchLink fieldCode="DE" term="%22COSMOGENIC+nuclides%22">COSMOGENIC nuclides</searchLink><br /><searchLink fieldCode="DE" term="%22CLIMATE+change%22">CLIMATE change</searchLink><br /><searchLink fieldCode="DE" term="%22PRINCIPAL+components+analysis%22">PRINCIPAL components analysis</searchLink><br /><searchLink fieldCode="DE" term="%22GEOMAGNETISM%22">GEOMAGNETISM</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Continuous reconstructions of past variations of the Earth's magnetic field are based mainly on paleomagnetic and cosmogenic 10Be records in marine sediments. In both cases, the recording mechanisms can be affected by environmental processes. Climatic overprints are only partially removed by normalization procedures, so that stacking is used to further remove site‐specific effects. Regionally or globally correlated artifacts, however, cannot be removed by stacking. Here we present a modified approach where geomagnetic records are complemented by environmental proxies representing processes that might affect the field recording mechanism. Geomagnetic and environmental records are jointly processed with principal component analysis to obtain a set of components supposed to represent true variations of the geomagnetic field and climatic overprints, respectively. After discussing the theoretical background of this new approach and its underlying assumptions, a practical example is presented, using a worst‐case scenario based on a single 10Be record from the North Atlantic with strong climatic overprints, covering the last 600 ka. The first two principal components, which represent the modulation of 10Be by global climatic variations and by the geomagnetic field, respectively, explain 66.3% of the signal variance. Comparison of the geomagnetic principal component with global relative paleointensity stacks shows that the original climatic overprint can be reduced by a factor of 2, outperforming a 10Be/9Be stack obtained from two sites with little glacial‐interglacial variability. The proposed method for removing climatic overprints can be applied to multiple sites more efficiently than conventional stacking. Plain Language Summary: Continuous records of the Earth's magnetic field rely on measurements of magnetic minerals or cosmogenic isotopes in sediments. Both types of records are also sensitive to environmental conditions and are thus affected by past climatic variations. These unwanted climatic overprints are difficult to remove: one strategy consists in stacking records from different sites; however, regionally or globally correlated artifacts cannot be completely removed by this technique. Here we present a new method for separating the geomagnetic signal from unwanted climatic overprint, which is based on the principal component analysis (PCA). The efficiency of this new method is tested with a worst‐case example based on a single site located in the North Atlantic, which is characterized by strong glacial‐interglacial variability. The first two principal components obtained from PCA represent the modulation of 10Be by global climatic variations and by the geomagnetic field, respectively. Comparisons of the geomagnetic field component with reference data show that the original climatic overprint has been reduced by a factor of 2, outperforming a 10Be/9Be stack obtained from two sites with little glacial‐interglacial variability. The proposed method for removing climatic overprints can be applied to multiple sites more efficiently than conventional stacking. Key Points: A new technique for removing climatic overprints from geomagnetic records is presentedA worst‐case example based on a single cosmogenic 10Be record yields a reduction of environmental overprints by a factor of 2Cosmogenic 10Be is a better geomagnetic field proxy for the North Atlantic Ocean than 10Be normalized by 9Be [ABSTRACT FROM AUTHOR] – Name: Abstract Label: Group: Ab Data: <i>Copyright of Geochemistry, Geophysics, Geosystems: G3 is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. 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.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1029/2024GC011761 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 26 StartPage: 1 Subjects: – SubjectFull: GEOMAGNETIC variations Type: general – SubjectFull: MAGNETIC field measurements Type: general – SubjectFull: COSMOGENIC nuclides Type: general – SubjectFull: CLIMATE change Type: general – SubjectFull: PRINCIPAL components analysis Type: general – SubjectFull: GEOMAGNETISM Type: general Titles: – TitleFull: Removing Climatic Overprints in Sedimentary Cosmogenic Beryllium Records: Potentials and Limits. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Savranskaia, Tatiana – PersonEntity: Name: NameFull: Egli, Ramon – PersonEntity: Name: NameFull: Simon, Quentin – PersonEntity: Name: NameFull: Valet, Jean‐Pierre – PersonEntity: Name: NameFull: Bassinot, Franck – PersonEntity: Name: NameFull: Thouveny, Nicolas IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 12 Text: Dec2024 Type: published Y: 2024 Identifiers: – Type: issn-print Value: 15252027 Numbering: – Type: volume Value: 25 – Type: issue Value: 12 Titles: – TitleFull: Geochemistry, Geophysics, Geosystems: G3 Type: main |
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