A reassessment of post-depositional remanent magnetism: preliminary experiments with natural sediments
A reassessment of post-depositional remanent magnetism: preliminary experiments with natural sediments
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DOI：
10.1016/s0012-821x(00)00255-7
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发表时间：
2000-11-30
影响因子：
5.3
通讯作者：
King, J
中科院分区：
文献类型：
--
作者：
Katari, K;Tauxe, L;King, J
沉积物-水界面下磁性颗粒的重新排列被认为是提供了沉积后剩余磁化(PDRM)。然而，在已发表的文献中，几乎没有令人信服的证据表明，PDRM是沉积物磁化的主要机制。我们在这里报告了两种实验室实验的初步结果，这些实验旨在研究磁性粒子在沉积后重新定向是否可能在自然界中发生。在第一个实验中，我们监测了天然沉积物磁化强度的变化，以响应实验室磁场的变化。我们的结果与磁性颗粒沉积后的重新取向不一致。在第二个实验中，我们将活的蠕虫放入一个多芯管中，而原始的沉积物-水界面保持不变。只有从地表形成的粪便颗粒中提取的样本才能观察到再磁化作用。这些颗粒被蠕虫悬浮，然后重新沉积在实验室的田野里。其他样本没有被重新悬浮，但仍然受到蠕虫的生物扰动，磁化强度没有变化。我们的初步结果不支持这样的假设，即沉积后重新定向发生在沉积物-水界面以下的自然、未受干扰的沉积物中。(C)2000 Elsevier Science B.V.保留所有权利。
Realignment of magnetic grains below the sediment-water interface is thought to impart a post-depositional remanent magnetization (pDRM). However, there is little convincing evidence in the published literature that pDRM is the dominant mechanism by which sediments become magnetized. We report here preliminary results from two kinds of laboratory experiments designed to investigate whether post-depositional reorientation of magnetic particles is likely to occur in nature. In the first experiment, we monitored changes in the magnetization of natural sediments in response to changing laboratory fields. Our results are inconsistent with post-depositional reorientation of magnetic particles. In a second experiment, we put live worms in a multi-core tube with the original sediment-water interface intact. Remagnetization was only observed in samples taken from a mound of fecal pellets formed at the surface. These pellets had been suspended by a worm, and redeposited in the laboratory field. The other samples, which were not resuspended, but nonetheless bioturbated by the worms, showed no change in magnetization. Our preliminary results do not support the hypothesis that post-depositional reorientation occurs in natural, undisturbed sediments below the sediment-water interface. (C) 2000 Elsevier Science B.V. All rights reserved.