The present and the mid-tertiary structure and deformation of southwest Japan and its implications for the formation of the Japan Sea /
Geological and geophysical data from SW Japan and the adjacent regions are analyzed to determine the nature of deformation in SW Japan, and the regional tectonic framework responsible for this deformation. The relationship of SW Japan tectonics to the opening of the Japan Sea is also explored. Hist...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1994.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=741964771&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD Link to OAKTrust copy |
| Summary: | Geological and geophysical data from SW Japan and the adjacent regions are analyzed to determine the nature of deformation in SW Japan, and the regional tectonic framework responsible for this deformation. The relationship of SW Japan tectonics to the opening of the Japan Sea is also explored. Historical geodetic triangulation and newer trilateration data suggest that SW Japan presently may be undergoing a clockwise rotational deformation. The form of rotation indicated in both the triangulation and the trilateration data is that of a rigid-body rotation, apparently about a point in SW Japan. However, the trilateration data, adjusted relative to southern Hokkaido, argue against this because SW Japan is not rotating about southern Hokkaido. The patterns of strike-slip faulting, used in conjunction with theoretical models, suggest that the geodetic rotations are due to edge-driven vertical axis block rotations. Critical in this analysis is the interaction between the Philippine Sea plate and SW Japan. When the Nankai Trough ruptures in a subduction zone great earthquake, - once every 100-150 years, the plate interface unlocks and the oblique slip vector is partitioned because the Hyuganada slab beneath Kyushu pulls westward the subducting Shikoku Basin, which, in turn, drags the outer zone towards the west. The Median Tectonic Line (MTL) is active only in its central one-third portion, in central Shikokuwestern Kii Peninsula where the coupling of the Philippine Sea plate - SW Japan interface is the strongest. As the MTL slips with right- lateral displacement after a subduction zone great earthquake, it causes the blocks to the north of it to rotate clockwise via Freund's [19741 Riedel shear mechanism. A fluid-like continuum character to the deformation, seen in kinematic vorticity number analysis, cannot be discounted, however. The style of deformation in SW Japan is right- lateral transtensional distributed simple shear. Clockwise paleomagnetic rotations observed in SW Japan are also explained by edge-driven vertical axis block rotations, via the pure shear-domain model of Ron et al. [19841, in response to the plate interactions described above. The Seto Inland Sea formed at block termination gaps, and tapped the high- magnesian Setouchi volcanism. The presentday structures and deformational style are apparently inherited from deformation initiated in middle Miocene time. The implications of the vertical axis block rotations in middle Miocene SW Japan are also investigated in light of the model mechanisms proposed for the engendering of the Japan Sea. |
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| Item Description: | "Major Subject: Geophysics". Vita. |
| Physical Description: | xii, 227 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |