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Abstract:
The primary data sources for reconstructing the Earth's magnetic field of the past millennia are archeomagnetic and sedimentary paleomagnetic data. Sediment records, in particular, are crucial in extending the temporal and spatial coverage of global Earth's magnetic field models, especially when archeomagnetic data is sparse. However, the post-depositional remanent magnetization (pDRM) process is still poorly understood and can cause smoothing of the magnetic signal and offsets with respect to the sediment age. To make effective use of sedimentary data, it is essential to understand the lock-in process and its impact on the magnetic signal. In this study, we investigate the lock-in process theoretically and derive a parameterized lock-in function to approximate all possible lock-in behaviors. Additionally, we demonstrate that a lock-in function that is independent of absolute parameters can only be applied to the magnetic direction components, but not to the relative intensity. Integrating this lock-in function into the ArchKalMag14k modeling procedure (Schanner et al., 2022, https://doi.org/10.1029/2021JB023166) allows to include data from sediment records. The parameters of the lock-in function are estimated by maximum likelihood methods using archeomagnetic data as a reference. The effectiveness of the proposed method is evaluated through synthetic tests. Additionally, it is applied to real sediment records. Our results demonstrate that the proposed method is capable of effectively correcting the distortion caused by the lock-in process, making data from sedimentary records a more reliable and informative source for Earth's magnetic field reconstructions.
