Miocene clockwise rotation of southwest Japan and formation of curvature of the Median Tectonic Line: Paleomagnetic implications

Otofuji, Yo–ichiro; Enami, Ryo; Yokoyama, Masahiko; Kamiya, Kazumasa; Kuma, Saori; Saito, Hiromi; Matsuda, T.

doi:10.1029/1999jb900086

Cited by 26 publications

(33 citation statements)

References 37 publications

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“…, Takahashi and Saito, 1997;, 1999;Otofuji et al, 19991980Itoh, 1986, 1988Hyodo and Niistuma, 1986;Takahashi and Nomura, 1989;, 1992;Takahashi and Watanabe, 1993;Hayashida, 1994;Takahashi and Saito, 1997;Otofuji et al, 1999;Itoh et al, 2006 MTL 80 Niitsuma andAkiba, 1985;Niitsuma and Matsuda, 1985;Hyodo and Niitsuma, 1986;Niistuma, 1989 6 Ma MTL Niitsuma, 1989 Takahashi and Saito 1997 Hyodo and Niitsuma, 1986;Takahashi and Watanabe, 1993 16 Ma 6 Ma (Hayashida and Ito, 1984); 2 = lower part of the Morozaki Group (Hayashida, 1986); 3 = Kani Group (Hayashida et al, 1991); 4 = Mizunami Group ; 5 = Hokusetsu Subgroup (Torii, 1983); 6 = Tomikusa Group (Hayashida, 1992); 7 = Kurami and Saigo groups (Hayashida, 1994); 8 = Chichibu basin sediments (Hyodo and Niitsuma, 1986). Accreted volcano-sedimentary units (Amano et al, 1999;Aoike, 1999) that initially formed on the Izu-Bonin Arc are also shown: K = Kushigatayama or Koma unit; M = Misaka unit.…”

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confidence: 99%

Paleomagnetic direction of the Lower Miocene Hokusetsu Subgroup in the Shitara area, Aichi Prefecture, and implications for the formation of the cuspate geologic structure in central Honshu

博幸

晃一

2012

Jour. Geol. Soc. Japan

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Collision between the eastern part of southwestern Japan (SWJ) and the Izu-Bonin Arc caused lateral bending of pre-Miocene geologic belts and boundary faults in central Honshu, including the Median Tectonic Line (MTL), producing a prominent cuspate structure. Paleomagnetic studies suggest that these geologic belts and the MTL were linear prior to that collision; however, a number of previously determined paleomagnetic directions have significant uncertainties and thus provide only poor constraints on the timing and amount of rotation that occurred during collision. Here, we present the results of a paleomagnetic study of sediments from the Hokusetsu Subgroup in Shitara, on the western limb of the cuspate structure, with the aim of obtaining a precise paleodirection. Samples were collected from sites within the uppermost Kadoya Formation, with principal component analysis of the results of stepwise demagnetization providing reliable site-mean directions for of these sites. Rock magnetic experiments determined that magnetite is the main remanence carrier, and these directions pass a fold test, indicating that magnetization predated tilting at Ma and is probably primary. The resultant overall mean direction has a NE declination: D (declination) = . °, I (inclination) = . °, α ( % confidence limit) = . °. The most likely cause of paleomagnetic deflection from the north is the clockwise rotation of SWJ relative to the Asian continent during the Early to Middle Miocene. The angle of deflection measured in these sediments is smaller than within the main part of SWJ, suggesting counterclockwise rotation in the western limb of the cuspate structure relative to the main part during or after clockwise rotation of SWJ. The Shitara paleodirection is deflected ° counterclockwise relative to the strike of the nearby MTL; this is also the case for the Chichibu area of the eastern limb, indicating that the MTL had the same strike direction in these two areas in the late Early Miocene.

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confidence: 99%

Paleomagnetic direction of the Lower Miocene Hokusetsu Subgroup in the Shitara area, Aichi Prefecture, and implications for the formation of the cuspate geologic structure in central Honshu

博幸

晃一

2012

Jour. Geol. Soc. Japan

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“…1). Previous paleomagnetic studies have dealt with the formation of the curvature and suggested that differential rotation of the Tokai and Hokuriku districts with respect to the central part of the southwest Japan arc (western Honshu including the San'in district) caused the curvature (Itoh, 1988;Itoh and Ito, 1989;Otofuji et al, 1999). However, the timing of the differential rotation has not been determined precisely because of the scarcity of Middle Miocene or younger paleomagnetic data.…”

Section: Introductionmentioning

confidence: 97%

“…In the southwest Japan arc, differential rotation of its eastern part including the Tokai and Hokuriku districts with respect to its central part including the San'in district has been documented (Itoh, 1988;Itoh and Ito, 1989;Otofuji et al, 1999). Paleomagnetic poles from Tokai and San'in are summarized in Table 2 and shown in Fig.…”

Section: Tectonic Implicationsmentioning

confidence: 99%

“…In Fig. 6(b), poles from Tokai are shown by solid circles (5 = ∼15 Ma pole from the Shitara dikes, 6 = Early Miocene grand-mean pole describe above, 7 = Paleogene pole from the Nohi Rhyolite reported by Otofuji et al (1999)), and those from San'in are shown by open squares (8 = ∼15 Ma pole from the Omori Formation, 9 = Early Miocene pole from the Hata Formation (Otofuji and Matsuda, 1984), 10 = Paleogene pole from the Sakurae Group (Otofuji and Matsuda, 1987)). In each district, no significant difference is found between the Early Miocene pole and the Paleogene one.…”

Section: Tectonic Implicationsmentioning

confidence: 99%

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Paleomagnetism of Miocene dikes in the Shitara basin and the tectonic evolution of central Honshu, Japan

Hoshi

Yokoyama

2014

Earth Planet Sp

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Central Honshu, Japan, is conspicuous for a northward-convex form of zonal geologic structures. To clarify the formation of curvature of the zonal structures in the west of the convex form and further to discuss the tectonic evolution of central Honshu, we carried out a paleomagnetic study of dated (∼15 Ma) dike rocks of the Shitara basin. Samples were collected from 25 basalt dikes trending north-south with a nearly vertical intrusion surface. After stepwise alternating-field and thermal demagnetization, 24 site-mean directions were determined. Three dikes gave anomalous directions, probably resulting from instantaneous recording of a field transition or excursion. The other 21 site-means produced a mean direction, D = 9.7• , I = 54.5• , α 95 = 5.2• , and a paleomagnetic pole at 82.3• N, 216.6Although the reversal test is negative at the 5% significance level, the mean direction and pole are time-averaged ones in which the secular variation is averaged out. This was confirmed by studying the angular standard deviation of virtual geomagnetic poles. We conclude that the central Honshu curvature formed when the southwest Japan arc rotated clockwise between 17 and 15 Ma in relation to the opening of the Japan Sea, associated with differential rotation of the eastern part of the arc with respect to the central part. The differential rotation probably resulted from a sinistral shear on the eastern margin of the rotating arc. The formation of the curvature seems not to have borne on the collision of the Izu-Ogasawara arc with Honshu, although the collision probably caused large-scale clockwise rotation of the Kanto Mountains in the east of the northward-convex structure.

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“…In the Nohi area (Fig. 1), which is located between the Yatsuo and the Mizunami area, Otofuji et al (1999) also suggested differential rotaion during the Miocene based on the paleomagnetic data obtained from Cretaceous to Paleogene welded tuff. In order to examine spatial difference in more various areas relative to the Yatsuo area, further investigation of precise age assignment in compared area is still necessary.…”

Section: Rotation During a Short Interval Around The Late Early Miocenementioning

confidence: 99%

Paleomagnetism of the Lower to Middle Miocene Series in the Yatsuo area, eastern part of southwest Japan: clockwise rotation and marine transgression during a short period

Tamaki

Itoh

Watanabe

2006

Bull. Geol. Surv. Japan

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Process of the tectonic rotation related to Japan Sea opening is viewed from tilt-corrected paleomagnetic data obtained from the Early to Middle Miocene sequence in the Yatsuo area on the Japan Sea coast, eastern part of southwest Japan. Progressive demagnetization experiments have been executed on samples obtained from two routes along the Yamada and Wada Rivers, and successfully isolated stable primary magnetic components in 16 sites. Together with data of previous studies, tilt-corrected reliable paleomagnetic directions comprising 10 normal and 27 reversed polarity sites of the Yatsuo Group on accurate stratigraphic positions show systematic temporal variation of easterly deflection in declinations. On the basis of our presented magnetostratigraphy, Yatsuo Group is assigned from the late Early to early Middle Miocene. Significant stage of rotation as much as 30 is specified during late Early Miocene between a period of active volcanism and subsequent period of marine transgression. We suggest that the Japan Sea opening event had a final phase of rapid rotation around the late Early Miocene, which seems to have caused marine transgression in relation to remarkable subsidence along the Japan Sea coast.

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Miocene clockwise rotation of southwest Japan and formation of curvature of the Median Tectonic Line: Paleomagnetic implications

Cited by 26 publications

References 37 publications

Paleomagnetic direction of the Lower Miocene Hokusetsu Subgroup in the Shitara area, Aichi Prefecture, and implications for the formation of the cuspate geologic structure in central Honshu

Paleomagnetic direction of the Lower Miocene Hokusetsu Subgroup in the Shitara area, Aichi Prefecture, and implications for the formation of the cuspate geologic structure in central Honshu

Paleomagnetism of Miocene dikes in the Shitara basin and the tectonic evolution of central Honshu, Japan

Paleomagnetism of the Lower to Middle Miocene Series in the Yatsuo area, eastern part of southwest Japan: clockwise rotation and marine transgression during a short period

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