Assessment of sedimentary beryllium data reliability for global geomagnetic field models

Records of paleomagnetic field intensity variations are of paramount importance for understanding the evolution and driving mechanisms sustaining the geodynamoin Earth’s core. One of the few means of obtaining continuous reconstructions of this evolution relies on sedimentary records. They provide an important tool for magnetostratigraphy, and allow us to trace the directional and intensity geomagnetic field changes in the past. Marine sedimentary sequences record the paleomagnetic field history by two independent mechanisms: the alignment of magnetic particles, which underlies continuous records of relative paleointensity (RPI), and the archival of cosmogenic isotopes, in particular 10Be, whose production by cosmic ray spallation is modulated by the shielding of the Earth’s magnetic field.

Insight on the change of the Earth's interior can be gained from global data-based models. The principal sources of paleomagnetic data used for global field modelling are natural remanent magnetisation of sediments, volcanic rocks and archeomagnetic fragments. The records of cosmogenic 10Be provide an independent source of data, unaffected by rock magnetic alterations, and could be complementary integrated into global field models. Present global magnetic field models do not include beryllium records. However, the implementation of cosmogenic 10Be should be done with caution due to persisting environmental contributions to the signal. The main objectives of this project are to filter out the misleading information unrelated to geomagnetic field changes by the a 10Be scaling routine and to assign uncertainties related to this method. Accurate error estimation is necessary for reliable recovery of magnetic field changes and robust geomagnetic field modelling. The methods to be developed will allow us to integrate the records of cosmogenic 10Be into global field models and to answer the questions related to global or regional simultaneous occurrence of geomagnetic excursions, their timing and mechanisms.

 

Time Frame

2022 – 2024

Funding

Alexander von Humboldt-Stiftung

Principal Investigators

  • Dr. Tatiana Savranskaia (GFZ)
  • Dr. Monika Korte (GFZ)
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