Paleomagnetic and rock magnetic studies of the Sakurajima 1914 and 1946 andesitic lavas from Japan: A comparison of the LTD-DHT Shaw and Thellier paleointensity methods

Yamamoto, Yuhji; Hoshi, Hiroyuki

doi:10.1016/j.pepi.2008.03.006

Cited by 33 publications

(36 citation statements)

References 49 publications

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“…The magnetic saturations initiated around 0.3 T for samples DS04-2 and SW01-17, while they are not observed for the others. Comparing these results with the corresponding VSM hysteresis curves by previous studies (Yamamoto and Hoshi 2008;Yamamoto et al 2010;Kodama 2013;Kodama 2015), no significant difference was observed in their patterns. However, it appears that the irreversibility of the M-H curves in Fig.…”

Section: Results and Interpretationssupporting

confidence: 60%

“…We measured a set of natural samples including four different kinds of Quaternary volcanic rocks (OS2-2, MY07-2, DS04-2, SW03-07) and one Paleozoic granite (SH03-07). These samples were selected on the grounds that their hysteresis measurements were well-documented by previous studies (Yamamoto and Hoshi 2008;Yamamoto et al 2010;Kodama 2013;Kodama 2015). They indicate that three of them (DS04-2, SW03-07, SH03-07) were saturated below 0.7 T (the pulse peak in this study), while the other two (OS2-2, MY07-2) showed no saturation plateau due to the superimposition of paramagnetic components.…”

Section: Samplesmentioning

confidence: 85%

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Pulsed-field magnetometry for rock magnetism

Kodama

2015

Earth Planet Sp

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An improved method is proposed for measuring dynamic magnetizations of bulk volcanic rock samples induced by a pulsed-field of 0.7 T and a duration of 10 ms. The transient magnetization is measured by a sensing system that consists of a pair of inductive differential coils, an analog preamplifier and integrator, and a high-speed digital storage scope. The system was calibrated using a paramagnetic salt (Gd 2 O 3 ) and was tested to different kinds of volcanic rocks with their magnetic properties well-documented previously. The results were comparable with those measured by a quasi-static method using a vibrating sample magnetometer, although there were small discrepancies in hysteresis parameters suggesting the time-dependence of the magnetic properties. The proposed system provides not only the magnetization over the short interval of a pulse but also the rapid (~3 ms) exponential decay after a pulse. The decay time constant was different among the samples under study, indicating the variations of their magnetic relaxation time. Although the present system is not sensitive enough to characterize varieties of natural samples including sediments, it has the potential as a versatile and convenient tool for rock magnetism.

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Section: Results and Interpretationssupporting

confidence: 60%

Section: Samplesmentioning

confidence: 85%

Pulsed-field magnetometry for rock magnetism

Kodama

2015

Earth Planet Sp

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“…Given that the Coe and IZZI protocols respond differently to MD effects, this is not possible here. We therefore restrict our analyses to only the 341 Coe protocol data (Pick and Tauxe, 1993;Muxworthy, 1998;Krása et al, 2003;Yamamoto et al, 2003;Bowles et al, 2006;Biggin et al, 2007;Donadini et al, 2007;Yamamoto and Hoshi, 2008;Paterson et al, 2010b;Muxworthy et al, 2011;Tanaka et al, 2012). The details of these data are given in their respective references.…”

Section: Testing Data Selectionmentioning

confidence: 99%

Thellier-type paleointensity data from multidomain specimens

Paterson

Biggin

Hodgson

et al. 2015

Physics of the Earth and Planetary Interiors

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“…The Tsunakawa-Shaw method, which has been previously called the LTD-DHT Shaw method (Tsunakawa and Shaw 1994;Yamamoto et al 2003), is one of such techniques. Its applicability and validity have been elucidated for various types of volcanic rocks from historical lava flows (e.g., Yamamoto et al 2003;Mochizuki et al 2004;Oishi et al 2005;Yamamoto and Hoshi 2008) but remain unassessed for archeological artifacts including baked clay.…”

Section: Introductionmentioning

confidence: 99%

Archeointensity study on baked clay samples taken from the reconstructed ancient kiln: implication for validity of the Tsunakawa-Shaw paleointensity method

Yamamoto

Torii

Natsuhara³

2015

Earth Planet Sp

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In 1972, a reconstruction experiment of a kiln had been done to reproduce an excavated kiln of the seventh century in Japan. Baked clay samples were taken from the floor surface and −20 cm level, and they have been stored after determinations of the paleomagnetic directions by partial alternating field demagnetizations. We recently applied the Tsunakawa-Shaw method to the samples to assess how reliable archeointensity results are obtained from the samples. A suite of the rock magnetic experiments and the scanning electron microscope observations elucidate that dominant magnetic carriers of the floor surface samples are Ti-poor titanomagnetite grains in approximately 10 nm size with single-domain and/or super-paramagnetic states, whereas contributions of multi-domain grains seem to be relatively large for the −20-cm level samples. From the floor surface samples, six out of the eight successful results were obtained and they give an average of 47.3 μT with a standard deviation of 2.2 μT. This is fairly consistent with the in situ geomagnetic field of 46.4 μT at the time of the reconstruction. They are obtained with a built-in anisotropy correction using anhysteretic remanent magnetization and without any cooling rate corrections. In contrast, only one out of four was successful from the −20-cm level samples. It yields an archeointensity of 31.6 μT, which is inconsistent with the in situ geomagnetic field. Considering from the in situ temperature record during the firing of the kiln and the unblocking temperature spectra of the samples, the floor surface samples acquired full thermoremanent magnetizations (TRMs) as their natural remanent magnetizations whereas the −20-cm level samples only acquired partial TRMs, and these differences probably cause the difference in the archeointensity results between the two sample groups. For archeointensity researches, baked clay samples from a kiln floor are considered to be ideal materials.

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Paleomagnetic and rock magnetic studies of the Sakurajima 1914 and 1946 andesitic lavas from Japan: A comparison of the LTD-DHT Shaw and Thellier paleointensity methods

Cited by 33 publications

References 49 publications

Pulsed-field magnetometry for rock magnetism

Pulsed-field magnetometry for rock magnetism

Thellier-type paleointensity data from multidomain specimens

Archeointensity study on baked clay samples taken from the reconstructed ancient kiln: implication for validity of the Tsunakawa-Shaw paleointensity method

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