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Titolo:
Paleomagnetism of Miocene dikes in the Shitara basin and the tectonic evolution of central Honshu, Japan
Autore:
Hoshi, H; Yokoyama, M;
Indirizzi:
Aichi Univ Educ, Dept Earth Sci, Kariya, Aichi 4488542, Japan Aichi Univ Educ Kariya Aichi Japan 4488542 , Kariya, Aichi 4488542, Japan
Titolo Testata:
EARTH PLANETS AND SPACE
fascicolo: 7, volume: 53, anno: 2001,
pagine: 731 - 739
SICI:
1343-8832(2001)53:7<731:POMDIT>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
K-AR AGES; SOUTHWEST JAPAN; CLOCKWISE ROTATION; MIDDLE MIOCENE; ROCKS; SEA; COLLISION; MOTION; NORTH; LINE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
38
Recensione:
Indirizzi per estratti:
Indirizzo: Hoshi, H Aichi Univ Educ, Dept Earth Sci, 1 Hirosawa, Kariya, Aichi 4488542, Japan Aichi Univ Educ 1 Hirosawa Kariya Aichi Japan 4488542 8542, Japan
Citazione:
H. Hoshi e M. Yokoyama, "Paleomagnetism of Miocene dikes in the Shitara basin and the tectonic evolution of central Honshu, Japan", EARTH PL SP, 53(7), 2001, pp. 731-739

Abstract

Central Honshu, Japan, is conspicuous for a northward-convex form of zonalgeologic structures. To clarify the formation of curvature of the zonal structures in the west of the convex form and further to discuss the tectonicevolution of central Honshu, we carried out a paleomagnetic study of dated(similar to 15 Ma) dike rocks of the Shitara basin. Samples were collectedfrom 25 basalt dikes trending north-south with a nearly vertical intrusionsurface. 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 degrees, I = 54.5 degrees, alpha (95) = 5.2 degrees, and a paleomagnetic pole at82.3 degreesN, 216.6 degreesE, A(95) = 6.2 degrees. Although 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. Thiswas 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 are 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.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 13:14:25