Geomagnetic anomalies of the seamounts near the Daito ridge and their tectonic implication.
This paper presents the results of three-dimensional magnetic analyses of seven seamounts in the Minami Daito Basin. The seamounts can be identified into two groups in terms of their magnetization, group A (Kanreki, Furou, Nisi-Kousei) has relatively strong magnetization intensity reflecting remanent magnetization, and the other, group B (Okina, Kijyu, Koki, Daito岳）， is characterized by normal magnetization with weak magnetization intensity. The inclination angle of magnetization vectors of Smt. Kanreki (N24.5＇’El33.0') and Smt. Furou (N24.4', El35.3') show that these seamounts were created in the southern hemisphere and then migrated northward to the present location. This migration is consistent with the paleomagnetic results of the DSDP site 446. The paleomagnetic poles of group-A are far apart from the apparent polar wander path estimated from seamounts in the Pacific Basin. This feature implies that these seamounts were undergone unti-clockwise rotation of about 40°～50°after their formation. Taking into account of paleomagnetic consistency between DSDP site 446 and seamounts Kanreki, Nisi-Kousei, the rotation may be correlated with the opening of the back-arc basin of the Minami Daito Basin. The paleomagnetic poles of group-B is rather close to the present magnetic pole of the earth’s dipole. This feature can be interpreted that magnetization of these semounts are mainly caused by induced magnetization rather than remanent manetization. Low magnetization intensity of group B also favours this assumption.
| Main Authors: | , , |
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| Format: | Journal Contribution biblioteca |
| Language: | Japanese |
| Published: |
1990
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| Online Access: | http://hdl.handle.net/1834/16071 |
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| Summary: | This paper presents the results of three-dimensional magnetic analyses of seven seamounts in the Minami Daito Basin. The seamounts can be identified into two groups in terms of their magnetization, group A (Kanreki, Furou, Nisi-Kousei) has relatively strong magnetization intensity reflecting remanent magnetization, and the other, group B (Okina, Kijyu, Koki, Daito岳）， is characterized by normal magnetization with weak magnetization intensity. The inclination angle of magnetization vectors of Smt. Kanreki (N24.5＇’El33.0') and Smt. Furou (N24.4', El35.3') show that these seamounts were created in the southern hemisphere and then migrated northward to the present location. This migration is consistent with the paleomagnetic results of the DSDP site 446. The paleomagnetic poles of group-A are far apart from the apparent polar wander path estimated from seamounts in the Pacific Basin. This feature implies that these seamounts were undergone unti-clockwise rotation of about 40°～50°after their formation. Taking into account of paleomagnetic consistency between DSDP site 446 and seamounts Kanreki, Nisi-Kousei, the rotation may be correlated with the opening of the back-arc basin of the Minami Daito Basin. The paleomagnetic poles of group-B is rather close to the present magnetic
pole of the earth’s dipole. This feature can be interpreted that magnetization of these semounts are mainly caused by induced magnetization rather than remanent manetization. Low magnetization intensity of group B also favours this assumption. |
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