Paleomagnetism of Miocene Sedimentary Rocks in the Kakegawa Area and Implication for Tectonic Rotation in Central Japan.

Hayashida, Akira

doi:10.5636/jgg.46.1051

Cited by 19 publications

(19 citation statements)

References 29 publications

(41 reference statements)

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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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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). Conflicting results have been reported from Lower Miocene sediments of Kakegawa (Hayashida, 1994;Hiroki and Matsumoto, 1999); a northerly remanence was reported by Hayashida (1994), while we can get a northeasterly mean direction by adopting only the reversed-polarity site-means determined by Hiroki and Matsumoto (1999). Most of the site-means of normal polarity measured by Hiroki and Matsumoto (1999) have a direction close to the geocentric axial dipole field direction in situ, so they would be affected by a viscous component.…”

Section: Tectonic Implicationsmentioning

confidence: 42%

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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“…As for the tectonic event, the ‘eastern’ part of the arc corresponds to the area between 136°E and 138°E, where a gradual increase in differential rotation angle was observed (Itoh & Ito 1989). Hayashida (1994) compiled reliable early Miocene paleomagnetic data, and described detailed patterns of the intra‐arc deformation. The present result, however, implies that the previous works may have adopted directional data sets representing various stages of coherent clockwise rotation of the arc.…”

Section: Discussionmentioning

confidence: 99%

Early Miocene rotational process in the eastern part of south‐west Japan inferred from paleomagnetic studies

Itoh

Kitada

2003

Island Arc

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This paper provides untilted paleomagnetic data obtained from the early Miocene strata around the Kanazawa‐Iozen area, in the eastern part of south‐west Japan. A thick pile of volcaniclastics and marine transgressive sediments underlie the area; they were deposited in the early stage of the Japan Sea opening event. Progressive thermal demagnetization tests isolated stable primary magnetic vectors from eight sites in the upper part of the Iozen Formation. Overall, the tilt‐corrected mean direction of this unit is D = 36.4°, I = 51.6° and α95 = 12.1. Together with a published paleomagnetic and chronological database, the present results suggest that clockwise rotation of south‐west Japan, linked to the back‐arc opening, commenced in the early Miocene and accelerated at the same time as rapid subsidence along the Japan Sea coast. Post‐opening, differential rotation within the eastern part of south‐west Japan is assumed, based on selected paleomagnetic data from the latest Early Miocene.

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Paleomagnetism of Miocene Sedimentary Rocks in the Kakegawa Area and Implication for Tectonic Rotation in Central Japan.

Cited by 19 publications

References 29 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

Early Miocene rotational process in the eastern part of south‐west Japan inferred from paleomagnetic studies

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