PSVM: A global database for the Miocene indicating elevated paleosecular variation relative to the last 10 Myrs.
PSVM: A global database for the Miocene indicating elevated paleosecular variation relative to the last 10 Myrs.
复制标题
PSVM：中新世的全球数据库，表明相对于过去 10 Myrs 的古世界变异有所增加。
DOI：
10.1002/essoar.10511095.1
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Engbers Y
中科院分区：
文献类型：
--
作者：
Engbers Y
古分子变化(PSV)的统计研究被用来推断地磁场的结构和行为。这项研究提供了一个新的数据库，即中新世的古分子变化(PSVM)，其中包括来自44个不同地点的1,454个站点的中新世(5.3-23 Ma)的高质量定向数据。该数据库用基于模型G的二次型对不同选择标准的古分子变异与纬度的关系进行了模拟。我们拟合的纬度不变的PSV(模型GA)的模型参数为15.6°，与纬度相关的PSV项(模型GB)为0.23。纬度不变项比过去10年或任何其他研究年龄的观测结果要高得多。我们还提出了一个新的时间平均场的随机模型BB-M22，它使用协变巨高斯过程(GGP)，该过程受PSVM、PINT和类地球发电机数值模拟的数据约束。与以前的GGP模型相比，BB-M22改进了对PSVM数据的拟合，因为它再现了在中新世观察到的较高的虚拟地磁极(VGP)分散度。我们的发现表明，与过去的十年相比，中新世时期的磁场更加多变，地球发电机更加活跃，这可能与核-地幔热流的升高有关。我们的结果表明，时间瞬时场的平均轴向偶极子优势比最近的时间要小。然而，我们注意到，倾角异常估计表明，不能排除中新世时平均场类似于地心轴偶极子的可能性。
Statistical studies of paleosecular variation (PSV) are used to infer the structure and behavior of the geomagnetic field. This study presents a new database, paleosecular variation of the Miocene (PSVM), of high‐quality directional data from the Miocene Epoch (5.3–23 Ma), compiled from 1,454 sites from 44 different localities. This database is used to model the latitude dependence of paleosecular variation with varying selection criteria using a quadratic form based on Model G. Our fitted model parameter for latitude‐invariant PSV (Model Ga) is 15.6° and the latitude dependent PSV term (Model Gb) is 0.23. The latitude invariant term is substantially higher than previously observed for the past 10 Myrs or any other studied ages. We also present a new stochastic model of the time‐average field, BB‐M22, using a covariant giant Gaussian process (GGP) which is constrained using data from PSVM, PINT and Earth‐like geodynamo numerical simulations. BB‐M22 improves the fit to PSVM data relative to prior GGP models, as it reproduces the higher virtual geomagnetic pole (VGP) dispersion observed during the Miocene. Our findings suggest a more variable magnetic field and more active geodynamo in the Miocene Epoch than the past 10 Myrs, perhaps linked to elevated core‐mantle heat flow. Our results suggest that the average axial dipole dominance of the time‐instantaneous field was lower than in more recent times. We note however, that the inclination anomaly estimates, suggest that it cannot be ruled out that the Miocene time averaged field resembles a geocentric axial dipole.