An experiment on the post-depositional remanent magnetization in artificial and natural sediments

Hamano, Yozo

doi:10.1016/0012-821x(80)90270-8

Cited by 71 publications

(50 citation statements)

References 21 publications

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“…The approximation by an exponential function is consistent with experimental results on magnetization processes in sediments (LOVLIE , 1976;TUCKER, 1980;HAMANO, 1980;OTOFUJI and SASAJIMA, 1981). Time-series of magnetization directions were smoothed before deconvolution to suppress highfrequency noise.…”

Section: Low-amplitude Secular Variationsupporting

confidence: 87%

Geomagnetic Secular Variation Reconstructed from Magnetizations of Wide-Diameter Cores of Holocene Sediments in Japan.

Hyodo

Itota

Yaskawa

1993

J. geomagn. geoelec

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A record of the secular variation of the geomagnetic field for the last 11000 years has been obtained from the remanent magnetization of seven wide-diameter (20 cm) cores of marine and lacustrine sediment from central to south-west Japan. Magnetization directions of five cores, possessing high-amplitude variations, exhibit good correlation. Two cores show lowamplitude variations, but they can be correlated well with other records after deconvolution to remove filtering effects of the post-depositional magnetization process. A composite secular variation curve was constructed by stacking the field direction records. Time constraints were obtained from radiocarbon ages of shell and wood fractions or tephrochronology. The secular variation curve agrees well with the archeomagnetic record after 1400 yrBP, with a slight difference in the time range 1400-2000 yrBP. The secular variation for the last 11000 years shows an elongated distribution of VGP's. The azimuth of the elongation, about 40°E, is consistent with that of VGP's from Japanese volcanic and sedimentary rocks during Brunhes epoch. The angular standard deviation is 14.5° (upper limit = 15.4°, lower limit = 13.7°). This estimate is slightly larger than that observed globally during Brunhes epoch and the position of the average VGP deviates 8.5° from the geographic north pole. These VGP analyses suggest a stationary nondipole source. The secular variation records from five northern hemisphere sites between 135°E and 95°W in longitude possess a single prominent feature: an extreme easterly swing in declination. A plot of age versus longitude of the swing at each site shows a clear westward drift, at a rate of about 0.13° /yr. The field vector around the swing represents clockwise looping at all the sites. This suggests that the swing is caused by a large non-dipole source which drifts at least from 135°E to 95°W in longitude.

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Section: Low-amplitude Secular Variationsupporting

confidence: 87%

Geomagnetic Secular Variation Reconstructed from Magnetizations of Wide-Diameter Cores of Holocene Sediments in Japan.

Hyodo

Itota

Yaskawa

1993

J. geomagn. geoelec

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“…The change appears to represent an exponential decrease with depth. HAMANO (1980) discussed on a red clay that the magnetization acquisition starts from the depth of 15cm, half of the total remanence being acquired at 80cm depth, and is completed at 2.5m. The third is that the partial PDRM acquired in some compaction range has an additive property (OTOFUJI and SASAJIMA,1981).…”

Section: Description Of Pdrmmentioning

confidence: 99%

Possibility of reconstruction of the past geomagnetic field from homogeneous sediments.

Hyodo

1984

J. geomagn. geoelec

101

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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.

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“…According to the zone-magnetization model (NIITSUMA, 1977) remanent magnetization becomes gradually permanent within a finite thickness of subsurface sediments (lock-in zone); Experiments by HAMANO (1980) and OTOFUJI and SASAJIMA (1981) showed that post-depositional remanent magnetization (PDRM) is acquired together with an increase in density of the sediments.…”

Section: Introductionmentioning

confidence: 99%

Fixation of remanent magnetization with compaction in deep-sea environment.

Yamazaki

1987

J. geomagn. geoelec

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An experiment on the post-depositional remanent magnetization in artificial and natural sediments

Cited by 71 publications

References 21 publications

Geomagnetic Secular Variation Reconstructed from Magnetizations of Wide-Diameter Cores of Holocene Sediments in Japan.

Geomagnetic Secular Variation Reconstructed from Magnetizations of Wide-Diameter Cores of Holocene Sediments in Japan.

Possibility of reconstruction of the past geomagnetic field from homogeneous sediments.

Fixation of remanent magnetization with compaction in deep-sea environment.

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