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| Yamazaki, T; Oda, H. |
| We have conducted a paleomagnetic study of six sediment cores taken from the equatorial Pacific, three from the West Caroline Basin and three from the Manihiki Plateau, in order to make a relative paleointensity stack during the Matuyama and late Gauss Chrons. The age of the bottom of the cores ranges from 1.2 to 3.0 Ma. The sediments show little downcore changes in the proxies of magnetic grain size and mineralogy and are hence suitable for estimating relative paleointensity. The age of the cores is controlled by correlating variations in magnetic concentration ( magnetic susceptibility and/or anhysteretic remanent magnetization (ARM)) to target oxygen-isotope (delta(18)O) curves. All cores from the Manihiki Plateau show an upward decrease of the natural... |
| Tipo: Text |
Palavras-chave: Equatorial Pacific; Excursion; Orbital modulation; Paleointensity; Paleomagnetism. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00232/34285/32650.pdf |
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| Yamazaki, Toshitsugu; Kanamatsu, Toshiya. |
| A paleomagnetic study was conducted on a sediment core KR0310-PC1 taken from the central North Pacific in order to obtain a relative paleointensity record in the Matuyama chron from this region. The core reached to about 1.6 Ma. The age control is based on the correlation of the S ratio (S-0.1T) variations with a global oxygen-isotope stack. Isothermal remanent magnetization (IRM) was used as the normalizer of the relative paleointensity estimation; anhysteretic remanent magnetization (ARM) was not adopted because ARM is sensitive to magnetostatic interaction among magnetic particles, which is evidenced in these sediments by an inverse correlation between the ratio of ARM to saturation IRM (SIRM) and SIRM without significant magnetic grain-size changes.... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Paleointensity; North Pacific; Orbital modulation; Normalizer; Magnetostatic interaction. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34631/32963.pdf |
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| Bouilloux, Alexandra; Valet, Jean-pierre; Bassinot, Franck; Joron, Jean-louis; Blanc-valleron, Marie-madeleine; Moreno, Eva; Dewilde, Fabien; Kars, Myriam; Lagroix, France. |
| Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Paleoenvironment; Goethite; Magnetite; Indian ocean. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37488/36828.pdf |
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| Heslop, David; Roberts, Andrew P.. |
| Principal component analysis (PCA) is a well-established technique in paleomagnetism and provides a means to estimate magnetic remanence directions from univectorial segments of stepwise demagnetization data. Derived directions constrain past geomagnetic field behavior and form the foundation of chronological and tectonic reconstructions. PCA of isolated remanence segments relies on estimates of the segment mean and covariance matrix, which can carry large uncertainties given the relatively small number of demagnetization data points used to characterize individual specimens. Traditional PCA does not, however, lend itself to quantification of these uncertainties, and inferences drawn from paleomagnetic reconstructions suffer from an inability to propagate... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Directional uncertainty; Principal component analysis. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53255/54707.pdf |
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| Valet, Jean-pierre; Moreno, Eva; Bassinot, Franck; Johannes, Lola; Dewilde, Fabien; Bastos, Tiago; Lefort, Apolline; Venec-peyre, Marie-therese. |
| High resolution measurements of climatic and magnetic parameters have been performed on two cores from the eastern China Sea and the western Caroline Basin. On both cores, magnetic parameters show a strong imprint of climatic changes but the absence of relationship between the inclination and the bulk density indicates that the directional changes do not depend on lithology. A weak 100 ka cycle is present in the China sea inclination variations, but this period is not in phase with the orbital eccentricity and thus not relevant. All normalization parameters yielded similar estimates of relative paleointensity (RPI), but we have noticed the persistence of climatic components in the signal. Principal Component Analysis (PCA) applied to different parameters... |
| Tipo: Text |
Palavras-chave: Magnetization; Paleointensity; Paleomagnetism; Sediments. |
| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00227/33818/32481.pdf |
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| Okada, Makoto; Suganuma, Yusuke; Haneda, Yuki; Kazaoka, Osamu. |
| The youngest geomagnetic polarity reversal, the Matuyama-Brunhes (M-B) boundary, provides an important plane of data for sediments, ice cores, and lavas. The geomagnetic field intensity and directional changes that occurred during the reversal also provide important information for understanding the dynamics of the Earth's outer core, which generates the magnetic field. However, the reversal process is relatively rapid in terms of the geological timescale; therefore, adequate temporal resolution of the geomagnetic field record is essential for addressing these topics. Here, we report a new high-resolution paleomagnetic record from a continuous marine succession in the Chiba composite section of the Kokumoto Formation of the Kazusa Group, Japan, that... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; Magnetostratigraphy; Matuyama-Brunhes boundary; Paleointensity; Marine isotope stage (MIS) 19; Chiba composite section. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00420/53174/55181.pdf |
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| Stoner, Joseph S.; Channell, James E. T.; Mazaud, Alain; Strano, Sarah E.; Xuan, Chuang. |
| Paleomagnetic analysis and radiocarbon dating of an expanded Holocene deep-sea sediment sequence recovered by Integrated Ocean Drilling Program (IODP) Expedition 303 from Labrador Sea Site U1305 (Lat.: 57 degrees 28.5 N, Long.: 48 degrees 31.8 W, water depth 3459 m) provides insights into mechanisms that drive both paleomagnetic secular variation (PSV) and magnetization acquisition in deep-sea sediments. Seventeen radiocarbon dates on planktonic foraminifera define postglacial (ca. 8 ka) sedimentation rates as ranging from 35 to > 90 cm/kyr. Alternating field (AF) demagnetization of u-channel samples show that these homogeneous sediments preserve a strong, stable, and consistently well-defined component magnetization. Normalized remanence records pass... |
| Tipo: Text |
Palavras-chave: Paleomagnetism; North Atlantic; Paleointensity. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00264/37480/36500.pdf |
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