Possibility of Reconstruction of the Past Geomagnetic Field from Homogeneous Sediments
Possibility of Reconstruction of the Past Geomagnetic Field from Homogeneous Sediments
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DOI：
10.5636/jgg.36.45
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
M. Hyodo
中科院分区：
文献类型：
--
作者：
M. Hyodo
利用线性系统理论对沉积物的磁化过程进行了描述。剩余磁化强度被表示为地磁场变化和力矩固定函数的卷积积分。制定的模型预测，通过过滤变形的字段变化被记录在磁化的沉积物，和原始字段推导出的磁化记录通过反卷积方法。将该模型应用于浅水沉积物岩心的磁化数据表明，剩余强度的变化可能反映了由于各个方向上排列的磁矩抵消而导致的强度降低，而不是场强的降低。根据磁化强度的测量结果和实验室实验，推断磁化区的宽度出乎意料地小。半固定深度，即视界中一半的磁矩被锁定的深度，似乎集中在10厘米或更少的地方。
Magnetizing process of a sediment is formulated using a linear system theory. Remanent magnetization is represented as a convolution integral of geomagnetic field variation and a moment fixing function. The formulated model predicts that a field variation is deformed by filtering to be recorded in magnetization of sediments, and that the original field is deduced from the record of magnetization by a deconvolution method. Application of the model to the magnetization data of a core of shallow water sediment reveals that the remanent intensity variation may reflect the intensity reduction due to the cancellation of magnetic moments aligned in various directions rather than decrease in a field intensity. Width of magnetizing zone is inferred to be unexpectedly small from results of measurement of magnetization and laboratory experiments. The half fixing depths, at which a half of magnetic moments in a horizon is locked in, seem to cluster around 10cm or less.