Miocene time-averaged geomagnetic field model suggests long lived mantle control and recurring structure in the South Atlantic
Miocene time-averaged geomagnetic field model suggests long lived mantle control and recurring structure in the South Atlantic
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中新世时间平均地磁场模型表明南大西洋长期存在的地幔控制和重复结构
DOI：
10.1016/j.epsl.2023.118535
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发表时间：
2024
影响因子：
5.3
通讯作者：
Engbers Y
中科院分区：
文献类型：
--
作者：
Engbers Y
长期时间平均地磁场结构的重建对于理解地磁场演化和识别非偶极场形态的寿命和规模具有重要意义。这项研究提出了MTAM 1，一个中新世（530 - 2300万年前）的非纬向时间平均场模型，或者实际上是500万年前之前的任何时间段。中新世的时间平均场模型是基于包括38个不同地点的定向数据汇编的逆模型，每个地点具有最少10个地点，称为PSVM（Engbers等人，2022 a）。将数据分为正态（PSVMN）和归一化反转（PSVMR）数据集，得到两个相应的模型MTAM 1 N和MTAM 1 R。考虑到相反的符号，这两种模型之间没有发现实质性的差异，这表明正常和反向场的形态之间的对称性，没有证据表明地磁场中的非反向特征。在这种对称性假设下，正常和反转数据可以一起建模，增强数据分布，从而增强中新世完整时间平均场模型的鲁棒性。模型的广泛结构类似于过去5百万年的时间平均场模型，但有一些明显的差异，特别是在南大西洋，所有中新世模型包括一个反向通量补丁（RFP）。为了研究这种差异是否是明确定义的，或者可能是由于建模方法或数据分布的差异造成的，我们将最近500万年的数据与我们的中新世正常模型作为先验约束进行了反演。我们没有发现证据表明中新世模型与过去500万年的数据所需的磁场结构不一致，这表明过去2300万年的平均地磁场形态总体稳定。这是一致的长期地幔控制地磁场形态，导致一致的偏离地心轴向偶极子在数百万年的时间尺度上的核幔边界（CMB）。
Reconstructions of long-term time-averaged geomagnetic field structures are important to understand geomagnetic field evolution and to identify the longevity and scale of non-dipolar field morphology. This study presentsMTAM1, a non-zonal time-averaged field model for the Miocene era (5.3–23 million years ago), or indeed any time period prior to 5 million years ago. The time averaged field model for the Miocene is an inverse model based on a directional data compilation comprising 38 different localities, each with a minimum of 10 sites, calledPSVM(Engbers et al., 2022a). The data were separated into normal (PSVMN) and normalised reversed (PSVMR) datasets, yielding two corresponding modelsMTAM1NandMTAM1R. Allowing for the opposite sign, no substantial differences were found between these two models, suggesting symmetry between the morphology of the normal and reversed fields and no evidence for non-reversing features in the geomagnetic field. Under this assumption of symmetry, the normal and reversed data can be modelled together, enhancing the data distribution and thus the robustness of the complete time-averaged field model for the Miocene. The broad structure of the models resembles previous time-averaged field models for the past 5 Myr but there are some clear differences, particularly under the South Atlantic, where all Miocene models include a reversed flux patch (RFP). To investigate whether this difference is well defined, or could result from differences in modelling methodology or data distribution, the data of the last 5 Myr were inverted with our normal model for the Miocene as a prior constraint. We find no evidence that the Miocene model is inconsistent with the field structures required by data from the past 5 Myr, suggesting an overall stability in the averaged geomagnetic field morphology for the past 23 Myr. This is consistent with long-term mantle control on geomagnetic field morphology leading to consistent deviations from the geocentric axial dipole on a multi-million-year timescale on the Core-Mantle boundary (CMB).
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影响因子：
3.7
作者：
Y. A. Engbers;R. Bono;A. Biggin
通讯作者：
Y. A. Engbers;R. Bono;A. Biggin
影响因子：
5.3
作者：
Constable, Catherine;Korte, Monika;Panovska, Sanja
通讯作者：
Panovska, Sanja
DOI：
10.1073/pnas.1722110115
发表时间：
2018-05-15
影响因子：
11.1
作者：
Brown, Maxwell;Korte, Monika;Gunnarson, Sydney
通讯作者：
Gunnarson, Sydney
地磁场分析——三、地核-地幔边界磁场
DOI：
--
发表时间：
1985
期刊：
影响因子：
--
作者：
D. Gubbins;J. Bloxham
通讯作者：
J. Bloxham
DOI：
10.1029/2021jb023358
发表时间：
2022-02
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
--
作者：
Y. A. Engbers;J. M. Grappone;D. Mark;A. Biggin
通讯作者：
Y. A. Engbers;J. M. Grappone;D. Mark;A. Biggin