Paleomagnetism and fission-track ages of Oki-Dogo Island in Southwest Japan

Kojima, Takeshi; Okada, Makoto; Ohira, Hiroto; Tokieda, Katsuyasu; Komuro, Hiroaki; Amano, Kazuo

doi:10.1186/bf03352361

Cited by 11 publications

(5 citation statements)

References 16 publications

(20 reference statements)

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“…Early Miocene palaeomagnetic directions from Southwest Japan show consistent declinations of about 40–50° (Hayashida & Ito 1984; Hayashida 1986; Hayashida et al 1991; Otofuji et al 1991; Kojima et al 2001). On the other hand, Late Cretaceous palaeomagnetic directions from Southwest Japan have larger declination values of about 70° (Otofuji & Matsuda 1987).…”

Section: Introductionmentioning

confidence: 94%

Late Cretaceous palaeomagnetic results from Southwest Japan: new insights for early Cenozoic clockwise rotation

Uno¹

2002

Geophysical Journal International

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Summary Palaeomagnetic samples in the Upper Cretaceous Arima Group have been collected from two areas in the middle of Southwest Japan. Tuffaceous sediments were sampled at eleven sites in the Arima area and welded tuffs were sampled at four sites in the Ikuno area. Thermal demagnetization isolated characteristic remanent magnetization components with unblocking temperatures of 500–580°C from all the sites. After tilt correction, the characteristic directions provide Late Cretaceous mean directions for the Arima area (D= 46.6°, I= 53.7°, α95= 3.7°) and the Ikuno area (D= 78.4°, I= 44.7°, α95= 9.5°). I interpret these data to show that the palaeomagnetic pole from the Arima area has been rotated counter‐clockwise relative to those from the central part of Southwest Japan, while the pole from the Ikuno area is in good agreement with palaeomagnetic poles from the central part of Southwest Japan. The pole for the Ikuno area together with previously reported ones give a new Late Cretaceous pole representative of the central part of Southwest Japan. This pole is rotated 64.6°± 15.5° clockwise with respect to the coeval one for the North China Block. In my model, the tectonic history of Southwest Japan includes Early Tertiary clockwise rotation of about 23° and Middle Miocene clockwise rotation of about 42°, resulting in a total rotation of Southwest Japan by 65°. The Early Tertiary clockwise rotation occurred in an area incorporating the Korean Peninsula and Southwest Japan, and the Middle Miocene clockwise rotation was associated with the opening of the Japan Sea.

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Section: Introductionmentioning

confidence: 94%

Late Cretaceous palaeomagnetic results from Southwest Japan: new insights for early Cenozoic clockwise rotation

Uno¹

2002

Geophysical Journal International

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“…; Iwaki & Itoh ; Hoshi & Yokoyama ; Kojima et al . ; Shimada et al . ; Itoh & Kitada ; Tamaki et al .…”

Section: Introductionunclassified

“…Extensive paleomagnetic studies of the circum-Japan Sea region (i.e., Japan, South Korea, northeast China, and eastern Russia) have been carried out since the 1980s to understand the tectonic evolution of this region. In Southwest Japan, remanent magnetization (or remanence) directions of Miocene age have been documented from a number of areas in order to constrain the tectonics of Southwest Japan, particularly those associated with the back-arc opening of the Japan Sea (e.g., Otofuji 1996;Ishikawa 1997;Hoshi et al 2000;Iwaki & Itoh 2000;Hoshi & Yokoyama 2001;Kojima et al 2001;Shimada et al 2001;Itoh & Kitada 2003;Tamaki et al 2006). Early Miocene or older directions (ca 23-16 Ma) generally yield northeast declinations, which have been interpreted as showing that Southwest Japan has experienced a clockwise rotation.…”

Section: Introductionmentioning

confidence: 99%

Instantaneous paleomagnetic record from the Miocene Kozagawa Dike of the Kumano Acidic Rocks, Kii Peninsula, Southwest Japan: cautionary note on tectonic interpretation

2013

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We have conducted a paleomagnetic investigation of the Kozagawa Dike, which is part of the Kumano Acidic Rocks that are the product of a Middle Miocene volcanoplutonic complex cropping out on the Kii Peninsula of Southwest Japan. The granite porphyry facies of the dike yields stable remanent magnetization components. Precisely determined site-mean directions of characteristic components, as revealed by principal component analysis of stepwise alternating-field and thermal demagnetization results, form a tight cluster. The overall mean direction exhibits an approximately 40°clockwise declination shift from the south and a steep negative inclination (D = 217.3°, I = -59.8°, a 95 = 2.8°; 10 sites). Rock magnetic analyses suggest that magnetite is the main stable component carrier. The overall mean direction is interpreted to be a geologically instantaneous record of the paleomagnetic field that was acquired in a relatively short time interval relative to paleomagnetic secular variations. The mean direction in geographic (in situ) coordinates obtained for the Kozagawa Dike is distinct from previously published data for laccolithic granite porphyry intrusions of the Kumano Acidic Rocks. This difference may result from a time lag during acquisition of remanent magnetization by the different units of the Kumano Acidic Rocks. The southwest and up paleomagnetic direction has previously been interpreted as representing clockwise rotation of Southwest Japan associated with back-arc opening of the Japan Sea. However, we contend that these directions actually reflect the transient capture of an extraordinary paleomagnetic field at ca 14.3 Ma, such as a transitional or excursional state, and are not of tectonic origin.

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“…Otofuji and Matsuda, 1983;Hayashida et al, 1991;Otofuji, 1996;Kojima et al, 2001;Hoshi et al, 201520° Ma et al, 1993Uno, 2002;Lin et al, 2003;Itoh et al, 2006;Uno et al, 2017 53 Ma Otofuji et al 2003B 53 Ma 84-53 Ma B , 1999Oda and Suzuki, 2000;Ando et al, 2001;Abrajevitch et al, 2011;Uno et al, 2012 Fig. . Equal area projections of the in situ mean direction of secondary remanent magnetization components observed from the Inuyama and Ajiro areas (with associated 95% confidence limits).…”

Section: -60°mentioning

confidence: 99%

Paleomagnetism of bedded cherts from southwest Japan

Uno

2018

Jour. Geol. Soc. Japan

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Paleomagnetic and rock magnetic data from bedded cherts in southwest Japan have been analyzed to constrain the paleolatitude of the site of deposition of the cherts, the movement of the oceanic plate on which the cherts were deposited, and secondary magnetization events that occurred in southwest Japan. The primary remanent magnetization component of the cherts reveals that they were deposited near the equator during the Middle Triassic, and were accreted to the eastern margin of the South China Block. The cherts record three types of secondary magnetization: viscous remanent magnetization, thermoviscous remanent magnetization, and chemical remanent magnetization. The latter two magnetization events are recognized over a distance of ~ km across southwest Japan and are considered to reflect widespread secondary magnetization in the region.

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Paleomagnetism and fission-track ages of Oki-Dogo Island in Southwest Japan

Cited by 11 publications

References 16 publications

Late Cretaceous palaeomagnetic results from Southwest Japan: new insights for early Cenozoic clockwise rotation

Late Cretaceous palaeomagnetic results from Southwest Japan: new insights for early Cenozoic clockwise rotation

Instantaneous paleomagnetic record from the Miocene Kozagawa Dike of the Kumano Acidic Rocks, Kii Peninsula, Southwest Japan: cautionary note on tectonic interpretation

Paleomagnetism of bedded cherts from southwest Japan

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