Geomagnetic anomalies at sea around central part of Honsyu Japan.
Surveys for “The Basic Map of the Sea" project were almost completed around Japan and their geomagnetic results around the central part of Honsyu were compiled. Complicated anomaly patterns caused by the Tertiary volcanic / plutonic rocks are widespread in the surveyed area in the Japan Sea, which would be typical geomagnetic characteristics in marginal seas in general. Very complicated anomaly patterns are also found along the Izu-Bonin ridge. Most of them are anomalies of basaltic or andesitic seamounts and some are considered to be caused by the seamounts or banks of acidic rocks. The geomagnetic field above the continental slopes along the Pacific shorelines is very smooth because of thick sedimentary rocks. The most western part of Japanese Lineation Set is found along the southern part of the Japan Trench. A geomagnetic anomaly map of the sea all around Japan, except in the Okinawa area, was also compiled using both present and past data. These results are compared with the geological characteristics,and marginal seas are considered to be an outcome of volcanic / plutonic activity at the volcanic front, which probably produced a large number of the crustal rocks in the island arc region.
| Main Authors: | , , , , |
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| Format: | Journal Contribution biblioteca |
| Language: | Japanese |
| Published: |
1981
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| Online Access: | http://hdl.handle.net/1834/16240 |
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